Posts tagged: firewall

The Ultimate VoIP Sandbox in the Cloud for Less Than a $35 Raspberry Pi 2

Last week we began our new series on Cloud Computing by documenting how to build an awesome LAMP server in the Cloud using Linux. Today we’re going to use the same platform but the price just dropped to $10.50 with coupon code TAKE70. We’ll show you how to build an equally powerful Incredible PBX 13 server with hundreds of PBX features including free calling to the U.S. and Canada using any (free) Google Voice account. Keep in mind this isn’t $10.50 a month for your cloud server. It’s $10.50, period! The whole project takes less than an hour. Before we begin, let’s revisit our cautionary note for those that missed last week’s article. It’s important.

There’s lots to hate at Cloud At Cost, a Canadian provider that offers virtual machines in the cloud for a one-time fee with no recurring charges. For $35 or less, you get a virtual machine with 512MB of RAM, 10GB of storage, and a gigabit Internet connection FOR LIFE. We haven’t seen a week go by when Cloud at Cost didn’t offer some sort of discount. Today it’s 70% which brings the total cost down to $10.50. That’s less than a burger at Five Guys. That’s the good news. But, if security, 99.999% reliability, performance, and excellent customer support are your must-haves, then look elsewhere. So why would anyone in their right mind sign up for a cloud solution that didn’t offer those four things? Did we mention it’s $10.50 for a lifetime cloud server?

If you take our recommendation and plunk down your $10.50, you’ll need to go into this with the right attitude. It’s not going to be flawless perfection computing. It’s a sandbox on which to experiment with [VoIP] and Cloud Computing. Will your virtual machine disintegrate at some juncture? Probably. Our experience is that the first couple days are critical. If you start seeing sluggish performance which degenerates to zero, don’t waste your time. Take good notes as you go along, delete the virtual machine, and rebuild a new one. It won’t cost you a dime, and it’ll save you hours of frustration. We suspect that bad folks get onto some of the servers and delight in bringing the machines to their knees. So the quicker you cut your losses, the better off you will be. Is CloudAtCost a good solution for production use? Absolutely not so don’t try to fit a square peg in the round hole. It’s not gonna work, and you WILL be disappointed.

Next we’ll cover three production-ready Cloud solutions that range in price from $5 to $15 a month. But today’s experiment will give you a platform on which to learn before you decide upon a more permanent deployment solution. And it will give you a terrific home for a backup server once you do move to a long-term solution so your $10.50 won’t be wasted.


The objective today is to show you how to build a rock-solid, secure VoIP server in the Cloud with all the bells and whistles you’d typically find on a PBX costing tens of thousands of dollars. Incredible PBX is pure GPL, open source code with one major difference. It’s FREE! And it’s supported by thousands of users on the PIAF Forum that started just like you.

Some of you are probably wondering why you would want a PBX at all. Hearing is believing as they say. Spend a couple minutes and call our demo server that we have preconfigured using everything covered in today’s tutorial. It’ll let you play with some of the features that a PBX offers such a voice dialing from a directory, news and weather forecasts, and much more. Just dial:

Nerd Vittles Demo IVR Options
1 – Call by Name (say “Delta Airlines” or “American Airlines” to try it out)
2 – MeetMe Conference (password is 1234)
3 – Wolfram Alpha (say “What planes are flying overhead now?”)
4 – Lenny (The Telemarketer’s Worst Nightmare)
5 – Today’s News Headlines
6 – Weather Forecast (say the city and state, province, or country)
7 – Today in History
8 – Speak to a Real Person (or maybe just voicemail if we’re out)

For long time readers of Nerd Vittles, you already know that the component we continually stress is security. Without that, the rest really doesn’t matter. You’ll be building a platform for someone else to hijack and use for nefarious purposes. When we’re finished today, you’ll have a cloud-based VoIP server that is totally invisible to the rest of the world except a short list of VoIP providers that have been thoroughly vetted by Nerd Vittles staff. You can whitelist additional locations and phones to meet your individual needs without worrying about your server being compromised.

Creating Your Virtual Machine Platform in the Cloud

To get started, you’ve got to cough up your $10.50 at Cloud at Cost using coupon code TAKE70. Once you’ve signed up, CloudAtCost will send you credentials to log into the Cloud at Cost Management Portal. Change your portal password IMMEDIATELY after logging in. Just go to SETTINGS and follow your nose.

To create your virtual machine, click on the CLOUDPRO button and click Add New Server. If you’ve only purchased the $10.50 CloudPRO 1 platform, then you’ll need all of the available resources shown in the pick list. Leave CentOS 6.7 64bit selected as the OS Type and click Complete. Depending upon the type of special pricing that Cloud at Cost is offering when you sign up, the time to build your virtual machine can take anywhere from a minute to the better part of a day. Things have settled down since the 90% off week so new servers typically are ready in a few minutes. However, we’ve learned to build new virtual machines at night where possible. Then they’re usually available for use by the next morning. Luckily, this slow performance does not impact existing virtual machines that already are running in the CloudAtCost hosting facilities.

Initial Configuration of Your CentOS 6.7 Virtual Machine

With a little luck, your virtual machine soon will appear in your Cloud at Cost Management Portal and look something like what’s shown above. The red arrow points to the i button you’ll need to click to decipher the password for your new virtual machine. You’ll need both your IP address and the password for the new virtual machine in order to log into the server which is now up and running with a barebones CentOS 6.7 operating system. Note the yellow caution flag. That’s telling you that Cloud at Cost will automatically shut down your server in a week to save (them) computing resources. You can change the setting to keep your server running 24/7. Click Modify, Change Run Mode, and select Normal – Leave Powered On. Click Continue and OK to save your new settings.

Finally, you’ll want to change the Host Name for your server to something more descriptive than c7…cloudpro.92… Click the Modify button again and click Rename Server to change it. IncrediblePBX13 has a nice ring to it, but to each his own.

Logging into Your New CentOS 6.7 Virtual Machine

In order to configure and manage your new CentOS 6.7 virtual machine, you’ll need to log into the new server using either SSH or, for Windows users, Putty. After installing Putty, run it and log in to the IP address of your VM with username root and the password you deciphered above. On a Mac, open a Terminal session and issue a command like this using the actual IP address of your new virtual machine:

ssh root@12.34.56.78

Before you do anything else, reset your Virtual Machine’s root password to something very secure: passwd

Installing Incredible PBX 13 with CentOS 6.7

Now we’re ready to build your VoIP server platform. There aren’t many steps so just cut-and-paste the code into your SSH or Putty session and review the results to make sure nothing comes unglued. If something does, the beauty of virtual machines is you can delete them instantly within your management portal and just start over whenever you like. So here we go…

We’ll begin by permanently turning off SELINUX which causes more problems than it solves. The first command turns it off instantly. The second line assures that it’ll stay off whenever you reboot your virtual machine.

setenforce 0
sed -i s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config

Now let’s bring CentOS 6.7 up to current specs and add a few important applications:

yum -y update
yum -y install net-tools nano wget tar

Now we’re ready to kick off the Incredible PBX 13 install:

cd /root
wget http://incrediblepbx.com/incrediblepbx13-12.2-centos.tar.gz
tar zxvf incrediblepbx*
./IncrediblePBX*

When the install begins, read the license agreement and press ENTER to agree to the terms and get things rolling. Now would be a great time to go have breakfast or lunch. Come back in about an hour and your server should be ready to go.

Tweaking Your CloudAtCost Setup Improves Performance and Improves Security

After you reboot your server, let’s address a couple of CloudAtCost quirks that may cause problems down the road. CloudAtCost has a nasty habit of not cleaning up after itself with fresh installs. The net result is your root password may get reset every time you reboot.

sed -i '/exit 0/d' /etc/rc.local
killall plymouthd
echo killall plymouthd >> /etc/rc.local
rm -f /etc/rc3.d/S97*
echo "exit 0" >> /etc/rc.local

Implementing Dynamic DNS Service on Your Client Machines

Unlike some other PBX offerings that leave your server exposed to the Internet, Incredible PBX is different. Unless the IP address from which you are accessing the server has been whitelisted, nobody on the Internet can see your server. The only exception is the preferred providers list and those on the same local area network (which is nobody in the case of CloudAtCost). As part of the Incredible PBX install, the IP address of the computer you used to perform the install was whitelisted automatically. But there may be other computers from which you wish to allow access to the PBX in order to deploy telephones at remote sites. Some of these sites may have dynamic IP addresses that change from time to time. Or you may have traveling salesman that land in a new hotel almost every night with a new IP address. Fortunately, there are a number of free and paid Dynamic DNS providers. For sites with dynamic IP addresses, simply choose a fully-qualified domain name (FQDN) to identify each location where you need computer access or need to deploy a phone. Then run a dynamic DNS update utility periodically from a computer or router at that site. It reports back the current public IP address of the site and your DNS provider updates the IP address assigned to that FQDN whenever there are changes.

DNS update clients are available for Windows, Mac OS X, and many residential routers. They’re also available for Android devices. Then it’s just a matter of plugging in the remote users’ FQDNs so Incredible PBX knows to give them server access via the whitelist. You implement this in seconds using the add-ip and add-fqdn utilities in the /root directory.

There are other ways to gain access as well using the PortKnocker utility or Travelin’ Man 4 from a telephone. Both of these are covered in the Incredible PBX 13 tutorial so we won’t repeat it here.

Incredible PBX Preliminary Setup Steps

First, let’s check things out and make sure everything is working as it should. With your favorite web browser, visit the IP address of your new server. You should see the default Incredible PBX page, the Kennonsoft Menu. It’s divided into two parts, a Users tab (shown below) and an Admin tab with additional options that we’ll cover shortly.

Now we need to jump back to SSH or Putty and log back into your server as root. You’ll note that the Incredible PBX Automatic Update Utility is run each time you log in. This is how important security updates are pushed to your server so do it regularly. And, no, you don’t need to contribute to our open source projects unless you want to. You’ll still get the updates as they are released.

After the Automatic Update Utility runs, the login script will execute status which tells you everything you need to know about the health of your server. After the initial install, it will look something like this with your server’s IP address obviously. We’ll cover the RED items down the road a bit.

For now, we need to complete a few preliminary setup steps for Incredible PBX to make sure you can log into the various components which have been installed on your computer. There are several different credentials you will need. Most of these are configured using scripts in the /root folder of your server. First, you need your root password for the server itself, and you should have already set that up with a very secure password using passwd. These same credentials are used to login to WebMin.

Next you’ll need an admin password for the Incredible PBX GUI. This is the management utility and Asterisk® code generator which consists of FreePBX® GPL modules that are open source and free to use. The admin password is set by running admin-pw-change in the /root directory.

There are also a number of web-based applications such as Telephone Reminders, AsteriDex, phpMyAdmin, and VoiceMail & Recordings (User Control Panel). You obviously don’t want everyone with a telephone using all of these applications so they are protected using a couple different Apache web server credentials. First, you set up an admin password for the administrator-level applications using the htpasswd utility. Then you set up an end-user account and password for access to AsteriDex, Reminders, and the User Control Panel. With the User Control Panel, end users also will need a username and password for their particular phone extension and this is configured with the Incredible PBX GUI using Admin -> User Management -> Add New User. If this sounds convoluted, it’s really not. Apache credentials can be entered once in an administrator’s or end user’s browser and they’re stored permanently.

Here is a checklist of the preliminary steps to complete before using your server:

Make your root password very secure: passwd
Create admin password for Incredible PBX GUI access: /root/admin-pw-change
Create admin password for web apps: htpasswd /etc/pbx/wwwpasswd admin
Create joeuser password for web apps: htpasswd /etc/pbx/wwwpasswd joeuser
Set up UCP accounts for Voicemail & Recordings access using Incredible PBX GUI
Make a copy of your Knock codes: cat /root/knock.FAQ
Decipher IP address and other info about your server: status
Set your correct time zone: /root/timezone-setup

Activating Incredible Fax on Your Server

Incredible PBX also includes an optional (and free) faxing component that lets you send and receive faxes that are delivered to your email address. To activate Incredible Fax, run the following script and plug in your email address for delivery of incoming faxes: /root/incrediblefax11.sh. After entering your email address, you’ll be prompted for all sorts of additional information. Unless you have unusual requirements, pressing the ENTER key at every prompt is the appropriate response. You’ll need to reboot your server again when the fax installation is complete. Once you log back into your server as root, the bottom line of the status display should now be green UP entries.

Managing Your Server with the Incredible PBX GUI

About 99% of your time managing your server will be spent in the Incredible PBX GUI. To access it, fire up your browser and point to the IP address of your server. At the Kennonsoft menu, click on the Users tab which will change to Admin and bring up the Admin menu shown here:

From the Administrator menu in the Kennonsoft GUI, click on Incredible PBX Administration. This will bring up the following menu:

Click on the first icon to access the Incredible PBX GUI. You’ll be prompted for your credentials. For the username, enter admin. For the password, enter the password you set up using admin-pw-change above. You should then be greeted by the main status display in the Incredible GUI:

If you’re new to Asterisk and FreePBX, here’s the one paragraph primer on what needs to happen before you can make free calls with Google Voice. You’ll obviously need a free Google Voice account. This gets you a phone number for people to call you and a vehicle to place calls to plain old telephones throughout the U.S. and Canada at no cost. You’ll also need a softphone or SIP phone (NOT a regular POTS telephone) to actually place and receive calls. YATE makes a free softphone for PCs, Macs, and Linux machines so download your favorite and install it on your desktop. Phones connect to extensions to work with Incredible PBX. Extensions talk to trunks (like Google Voice) to make and receive calls. We use outbound routes to direct outgoing calls from extensions to trunks, and we use inbound routes to route incoming calls from trunks to extensions to make your phones ring. In a nutshell, that’s how a PBX works. There are lots of bells and whistles that you can explore down the road.

As configured after installation, you have everything you’ll need except a Google Voice trunk, and we’ll cover that next. Then we’ll add a softphone with your extension 701 credentials, and you’ll be ready to make and receive calls. Before we move on, let’s decipher your extension 701 password so that you’ll have it for later. Choose Applications -> Extensions -> 701 and scroll down the screen to the Secret field and write down your password. You can also change it if you like and click Submit and then the Red button to update your settings. While you’re here, write down your extension 701 Voicemail Password.

Deploying Google Voice on Your Server

That leaves one RED entry on your status display, GV OAUTH. Whether to use plain text passwords or OAUTH 2 credentials with Google Voice accounts presently is a matter of choice although Google regularly threatens to discontinue access to Google Voice without OAUTH authentication. We suggest you play with Google Voice using plain text passwords just to get your feet wet because OAUTH implementation gets complicated. When you get ready to deploy a permanent Incredible PBX server, that would be the appropriate time to switch to OAUTH. This tutorial (beginning at step 1b) will guide you through the process.

If you want to use Google Voice, you’ll need a dedicated Google Voice account to support Incredible PBX. If you want to use the inbound fax capabilities of Incredible Fax, then you’ll need an additional Google Voice line that can be routed to the FAX custom destination using the GUI. The more obscure the username (with some embedded numbers), the better off you will be. This will keep folks from bombarding you with unsolicited Gtalk chat messages, and who knows what nefarious scheme will be discovered using Google messaging six months from now. So keep this account a secret!

We’ve tested this extensively using an existing Gmail account, and inbound calling is just not reliable. The reason seems to be that Google always chooses Gmail chat as the inbound call destination if there are multiple registrations from the same IP address. So, be reasonable. Do it our way! Set up a dedicated Gmail and Google Voice account, and use it exclusively with Incredible PBX. It’s free at least through 2013. Google Voice no longer is by invitation only so, if you’re in the U.S. or have a friend that is, head over to the Google Voice site and register.

You must choose a telephone number (aka DID) for your new account, or Google Voice calling will not work… in either direction. Google used to permit outbound Gtalk calls using a fake CallerID, but that obviously led to abuse so it’s over! You also have to tie your Google Voice account to at least one working phone number as part of the initial setup process. Your cellphone number will work just fine. Don’t skip this step either. Just enter the provided 2-digit confirmation code when you tell Google to place the test call to the phone number you entered. Once the number is registered, you can disable it if you’d like in Settings, Voice Setting, Phones. But…

IMPORTANT: Be sure to enable the Google Chat option as one of your phone destinations in Settings, Voice Setting, Phones. That’s the destination we need for The Incredible PBX to work its magic! Otherwise, all inbound and outbound calls will fail. If you don’t see this option, you may need to call up Gmail and enable Google Chat there first. Then go back to the Google Voice Settings.

While you’re still in Google Voice Settings, click on the Calls tab. Make sure your settings match these:

  • Call ScreeningOFF
  • Call PresentationOFF
  • Caller ID (In)Display Caller’s Number
  • Caller ID (Out)Don’t Change Anything
  • Do Not DisturbOFF
  • Call Options (Enable Recording)OFF
  • Global Spam FilteringON

Click Save Changes once you adjust your settings. Under the Voicemail tab, plug in your email address so you get notified of new voicemails. Down the road, receipt of a Google Voice voicemail will be a big hint that something has come unglued on your PBX.

One final word of caution is in order regardless of your choice of providers: Do NOT use special characters in any provider passwords, or nothing will work!

Once you have your Google Voice account properly configured with Google, here is the proper sequence to get a Google Voice account working with Incredible PBX. First, using a browser, login to your Google Voice account. Second, make sure that Google Chat is activated in your Phone -> Settings. Third, in a separate browser tab, enable Less Secure Apps for your Google account. Fourth, in another separate browser tab, activate the Google Voice reset procedure. Fifth, in the Incredible PBX GUI, choose Connectivity -> Google Voice (Motif) and enter your Google Voice credentials:

Sixth, save your settings by clicking Submit and the Red Button to reload the GUI. Finally, using SSH or Putty, log into your server as root and restart Asterisk: amportal restart.

Setting Up a Soft Phone to Use with Incredible PBX

Now you’re ready to set up a telephone so that you can play with Incredible PBX. We recommend YateClient which is free. Download it from here. Run YateClient once you’ve installed it and enter the credentials for the 701 extension on Incredible PBX. You’ll need the IP address of your server plus your extension 701 password. Choose Settings -> Accounts and click the New button. Fill in the blanks using the IP address of your server, 701 for your account name, and your extension 701 password. Click OK.

Once you are registered to extension 701, close the Account window. Then click on YATE’s Telephony Tab and place some test calls to the numerous apps that are preconfigured on Incredible PBX. Dial a few of these to get started:


DEMO - Allison's IVR Demo
947 - Weather by ZIP Code
951 - Yahoo News
*61 - Time of Day
*68 - Wakeup Call
TODAY - Today in History

Now you’re ready to connect to the telephones in the rest of the world. If you live in the U.S., the easiest way (at least for now) is to use the free Google Voice account we set up above. Unlike traditional telephone service where you were 100% dependent upon MaBell, there is no such limitation with VoIP. The smarter long-term solution is to choose several SIP providers and set up redundant trunks for your incoming and outbound calls. The PIAF Forum includes dozens of recommendations to get you started. Here are a few of our favorites:

Originally published: Friday, January 29, 2016





Need help with Asterisk? Visit the PBX in a Flash Forum.


 
Awesome Vitelity Special. Vitelity has generously offered a terrific discount for Nerd Vittles readers. You now can get an almost half-price DID from our special Vitelity sign-up link. If you’re seeking the best flexibility in choosing an area code and phone number plus the lowest entry level pricing plus high quality calls, then Vitelity is the hands-down winner. Vitelity provides Tier A DID inbound service in over 3,000 rate centers throughout the US and Canada. When you use our special link to sign up, Nerd Vittles gets a few shekels down the road to support our open source development efforts while you get an incredible signup deal as well. The going rate for Vitelity’s DID service is $7.95 a month which includes up to 4,000 incoming minutes on two simultaneous channels with terminations priced at 1.45¢ per minute. Not any more! For our users, here’s a deal you can’t (and shouldn’t) refuse! Sign up now, and you can purchase a Tier A DID with unlimited incoming calls and four simultaneous channels for just $3.99 a month. To check availability of local numbers and tiers of service from Vitelity, click here. NOTE: You can only use the Nerd Vittles sign-up link to order your DIDs, or you won’t get the special pricing! Vitelity’s rate is just 1.44¢ per minute for outbound calls in the U.S. There is a $35 prepay when you sign up. This covers future usage. Any balance is refundable if you decide to discontinue service with Vitelity.


Some Recent Nerd Vittles Articles of Interest…

The Ultimate Linux Sandbox in the Cloud for Less Than a $35 Raspberry Pi 2

Every few years we like to drop back and take a fresh look at the best way to get started with Linux. For those coming from the Windows World, it can be a painful process. Learning with a Cloud-based server can be especially dangerous because of the security risks. And then there’s the cost factor. Not everyone has several hundred dollars to buy hardware and, frankly, learning about Linux on a $35 Raspberry Pi can drive most newbies to drink. So today we’ll show you another way. It’s not necessarily a better way. But it’s different, and it’s loads of fun for not much money. Today’s project only takes 30 minutes.

There’s lots to hate at Cloud At Cost, a Canadian provider that offers virtual machines in the cloud for a one-time fee with no recurring charges. For $35 or less, you get a virtual machine with 512MB of RAM, 10GB of storage, and a gigabit Internet connection FOR LIFE. We haven’t seen a week go by when Cloud at Cost didn’t offer some sort of discount. Today it’s 70% off with coupon code TAKE70 which brings the total cost down to $10.50. That’s less than a burger at Five Guys. That’s the good news. But, if security, 99.999% reliability, performance, and excellent customer support are your must-haves, then look elsewhere. So why would anyone in their right mind sign up for a cloud solution that didn’t offer those four things? Did we mention it’s $10.50 for a lifetime cloud server?

If you take our recommendation and plunk down your Alexander Hamilton, you’ll need to go into this with the right attitude. It’s not going to be flawless perfection computing. It’s a sandbox on which to experiment with Linux and Cloud Computing. Will your virtual machine disintegrate at some juncture? Probably. Our experience is that the first couple days are critical. If you start seeing sluggish performance which degenerates to zero, don’t waste your time. Take good notes as you go along, delete the virtual machine, and rebuild a new one. It won’t cost you a dime, and it’ll save you hours of frustration. We suspect that bad folks get onto some of the servers and delight in bringing the machines to their knees. So the quicker you cut your losses, the better off you will be. Is CloudAtCost a good solution for production use? Absolutely not so don’t try to fit a square peg in the round hole. It’s not gonna work, and you WILL be disappointed. You’ve been warned. Let’s get started. ENJOY THE RIDE!

Our objective today is to show you how to build a rock-solid, secure Linux server in the Cloud with all the bells and whistles that make Linux the server platform of choice for almost every organization in the world. We’ll finish up by showing you how to embellish the platform with WordPress to do something that’s special for you whether it’s your own blog like Nerd Vittles, or a school newspaper, or an on-line shopping site to sell comic books. The basic foundation for most Linux platforms is called a LAMP server which stands for Linux, Apache, MySQL, and PHP. Linux is an open source operating system that includes contributions from thousands of developers around the world. Apache is the web server platform on which most commercial businesses stake their reputation. MySQL is the open source database management system now owned by Oracle. If it’s good enough for Facebook, it’s good enough for you. And PHP is THE web-based programming language that will let you build almost any application using Linux, Apache, and MySQL.

So what’s the big deal? There are thousands of online tutorials that will show you how to build a LAMP server. For long time readers of Nerd Vittles, you already know that the component we continually stress is security. Without that, the rest really doesn’t matter. You’ll be building a platform for someone else to hijack and use for nefarious purposes. When we’re finished today, you’ll have a cloud-based server that is totally invisible to the rest of the world with the exception of its web interface. And we’ll show you a simple way to reduce the exposure of your web interface to some of its most likely attackers. Will it be 100% secure? Nope. If you have a web server on the public Internet, it’s never going to be 100% secure because there’s always the chance of a software bug that nobody has yet discovered and corrected. THAT’S WHAT BACKUPS ARE FOR!

Creating Your Virtual Machine Platform in the Cloud

To get started, you’ve got to plunk down your $10.50 at Cloud at Cost using coupon code TAKE70. Once you’ve paid the piper, they will send you credentials to log into the Cloud at Cost Management Portal. Change your password IMMEDIATELY after logging in. Just go to SETTINGS and follow your nose.

To create your virtual machine, click on the CLOUDPRO button and click Add New Server. If you’ve only purchased the $10.50 CloudPRO 1 platform, then you’ll need all of the available resources shown in the pick list. Leave CentOS 6.7 64bit selected as the OS Type and click Complete. Depending upon the type of special pricing that Cloud at Cost is offering when you sign up, the time to build your virtual machine can take anywhere from a minute to the better part of a day. We’ve learned to build new virtual machines at night, and they’re usually available for use by the next morning. Luckily, this slow performance does not impact existing virtual machines that already are running in their hosting facility.

Initial Configuration of Your CentOS 6.7 Virtual Machine

With a little luck, your virtual machine soon will appear in your Cloud at Cost Management Portal and look something like what’s shown above. The red arrow points to the i button you’ll need to click to decipher the password for your new virtual machine. You’ll need both the IP address and the password for your new virtual machine in order to log into the server which is now up and running with a barebones CentOS 6.7 operating system. Note the yellow caution flag. That’s telling you that Cloud at Cost will automatically shut down your server in a week to save (them) computing resources. You can change the setting to keep your server running 24/7. Click Modify, Change Run Mode, and select Normal – Leave Powered On. Click Continue and OK to save your new settings.

Finally, you’ll want to change the Host Name for your server to something more descriptive than c7…cloudpro.92… Click the Modify button again and click Rename Server to make the change. Your management portal then will show the new server name as shown above.

Logging into Your CentOS 6.7 Virtual Machine

In order to configure and manage your new CentOS 6.7 virtual machine, you’ll need to log into the new server using either SSH or, for Windows users, Putty. After installing Putty, run it and log in to the IP address of your VM with username root and the password you deciphered above. On a Mac, open a Terminal session and issue a command like this using the actual IP address of your new virtual machine:

ssh root@12.34.56.78

Before you do anything else, reset your root password to something very secure: passwd

Installing the LAMP Server Basics with CentOS 6.7

Now we’re ready to build your LAMP server platform. We’ve chopped this up into lots of little steps so we can explain what’s happening as we go along. There’s nothing hard about this, but we want to document the process so you can repeat it at any time. As we go along, just cut-and-paste each clump of code into your SSH or Putty session and review the results to make sure nothing comes unglued. If something does, the beauty of virtual machines is you can delete them instantly within your management portal and just start over whenever you like. So here we go…

We’ll begin by permanently turning off SELINUX which causes more problems than it solves. The first command turns it off instantly. The second line assures that it’ll stay off whenever you reboot your virtual machine.

setenforce 0
sed -i s/SELINUX=enforcing/SELINUX=disabled/g /etc/selinux/config

Now let’s bring CentOS 6.7 up to current specs and add a few important applications:

yum -y update
yum -y install nano wget expect net-tools dialog git xz
yum -y install kernel-headers
yum -y install kernel-devel

Next, we’ll set up your Apache web server and configure it to start whenever you reboot your server:

yum -y install httpd
service httpd start
chkconfig httpd on

Now let’s set up your MySQL server, bring it on line, and make sure it restarts after server reboots. Unless you plan to add Asterisk® and FreePBX® to your server down the road, you’ll want to uncomment the two commands that begin with # by removing the # symbol and replacing new-password with a very secure password for your root user account in MySQL. Be sure to run the last command to secure your server. After logging in, the correct answers are n,Y,Y,Y,Y.

yum -y install mysql mysql-server
service mysqld start
chkconfig mysqld on
#/usr/bin/mysqladmin -u root password 'new-password'
#/usr/bin/mysqladmin -u root -p -h localhost.localdomain password 'new-password'
mysql_secure_installation

Next, we’ll set up PHP and configure it to work with MySQL:

yum -y install php
yum -y install php-mysql
service httpd restart

Finally let’s get SendMail installed and configured. Insert your actual email address in the last line and send yourself a test message to be sure it’s working. Be sure to check your spam folder since the message will show a sender address of localhost which many email systems including Gmail automatically identify as spam.

yum -y install sendmail
rpm -e postfix
service sendmail restart
yum -y install mailx
echo "test" | mail -s testmessage youracctname@yourmailserver.com

Installing Supplemental Repositories for CentOS 6.7

One of the beauties of Linux is not being totally dependent upon CentOS for all of your packaged applications. Let’s add a few other repositories that can be used when you need to add a special package that is not in the CentOS repository. Let’s start with EPEL. We’ll disable it by default and only use it when we need it.

yum -y install http://epel.mirror.net.in/epel/6/i386/epel-release-6-8.noarch.rpm
sed -i 's|enabled=1|enabled=0|' /etc/yum.repos.d/epel.repo

We actually need the EPEL repo to install Fail2Ban for monitoring of attacks on certain Linux services such as SSH:

yum --enablerepo=epel install fail2ban -y
cd /etc
wget http://incrediblepbx.com/fail2ban-lamp.tar.gz
tar zxvf fail2ban-lamp.tar.gz

We also need the EPEL repo to install ipset, a terrific addition to the IPtables Linux firewall that lets you quickly block entire countries from accessing your server:

yum --enablerepo=epel install ipset -y

Next, we’ll add a sample script that documents how the country blocking mechanism works with ipset.1 For a complete list of countries that can be blocked, go here. If you need a decoder badge to match abbreviations against country names, you’ll find it here. To add other countries, simply edit the shell script and clone lines 4-7 using the names of the countries and country zone files that you wish to add. Be sure to insert the new lines before the commands to restart iptables and fail2ban. This script will need to be run each time your server reboots and before IPtables is brought on line. We’ll handle that a little later.

echo "#\!/bin/bash" > /etc/block-china.sh
echo " " >> /etc/block-china.sh
echo "cd /etc" >> /etc/block-china.sh
echo "ipset -N china hash:net" >> /etc/block-china.sh
echo "rm cn.zone" >> /etc/block-china.sh
echo "wget -P . http://www.ipdeny.com/ipblocks/data/countries/cn.zone" >> /etc/block-china.sh
echo "for i in $(cat /etc/cn.zone ); do ipset -A china $i; done" >> /etc/block-china.sh
echo "service iptables restart" >> /etc/block-china.sh
echo "service fail2ban restart" >> /etc/block-china.sh
sed -i 's|\||' /etc/block-china.sh
chmod +x /etc/block-china.sh

Another important repository is REMI. It is especially helpful if you decide to upgrade PHP from the default version 5.3 to one of the newer releases: 5.5 or 5.6. In this case, you’ll want to activate the specific repository to support the release you choose in /etc/yum.repos.d/remi-safe.repo.

yum -y install http://rpms.famillecollet.com/enterprise/remi-release-6.rpm
sed -i 's|enabled=1|enabled=0|' /etc/yum.repos.d/remi-safe.repo

One final repository to have on hand is RPMForge, now renamed RepoForge. We’ll use it in a bit to install a dynamic DNS update utility which you actually won’t need at CloudAtCost since your server is assigned a static IP address. But it’s handy to have in the event you wish to assign a free FQDN to your server anyway.

yum -y install http://pkgs.repoforge.org/rpmforge-release/rpmforge-release-0.5.3-1.el6.rf.x86_64.rpm
sed -i 's|enabled = 1|enabled = 0|' /etc/yum.repos.d/rpmforge.repo

Adding a Few Utilities to Round Out Your LAMP Server Deployment

If you’re like us, you’ll want to test the speed of your Internet connection from time to time. Let’s install a free script that you can run at any time by logging into your server as root and issuing the command: /root/speedtest-cli

cd /root
wget -O speedtest-cli https://raw.githubusercontent.com/sivel/speedtest-cli/master/speedtest_cli.py
chmod +x speedtest-cli

Next, let’s put in place a simple status display which will quickly tell you what’s running and what’s not. We’ve borrowed some GPL code from Incredible PBX to help you out. Run status-lamp at any time for a snapshot of your server.

cd /usr/local/sbin
wget http://incrediblepbx.com/status-lamp.tar.gz
tar zxvf status-lamp.tar.gz
rm -f status-lamp.tar.gz

Now we’ll put the Linux Swiss Army Knife in place. It’s called WebMin, and it provides a GUI to configure almost everything in Linux. Pick up a good WebMin book from your public library to get started. Once installed, you access WebMin from your browser at the IP address of your server on the default port of 10000: https://serverIPaddress:10000. It’s probably a good idea to change this port number and the commented out line shows how to do it with the new port being 9001 in the example. The way in which we typically configure the Linux firewall will block all access to WebMin except from an IP address which you have whitelisted, e.g. your home computer’s public IP address.

cd /root
yum -y install perl perl-Net-SSLeay openssl perl-IO-Tty
yum -y install http://prdownloads.sourceforge.net/webadmin/webmin-1.780-1.noarch.rpm
#sed -i 's|10000|9001|g' /etc/webmin/miniserv.conf
service webmin restart
chkconfig webmin on

Tweaking Your CloudAtCost Setup Improves Performance and Improves Security

Finally, let’s address a couple of CloudAtCost quirks that may cause problems down the road. CloudAtCost has a nasty habit of not cleaning up after itself with fresh installs. The net result is your root password gets reset every time you reboot.

killall plymouthd
echo killall plymouthd >> /etc/rc.local
rm -f /etc/rc3.d/S97*

With the exception of firewall configuration, which is so important that we’re covering it separately below, you now have completed the LAMP server installation. After completing the firewall steps in the next section, simply reboot your server and you’re ready to go.

The Most Important Step: Configuring the Linux IPtables Firewall

RULE #1: DON’T BUILD SERVERS EXPOSED TO THE INTERNET WITHOUT ROCK-SOLID SECURITY!

As installed by CloudAtCost, your server provides ping and SSH access from a remote computer and nothing else. The good news: it’s pretty safe. The bad news: it can’t do anything useful for anybody because all web access to the server is blocked. We want to fix that, tighten up SSH access to restrict it to your IP address, and deploy country blocking to show you how.

As we implement the firewall changes, you need to be extremely careful in your typing so that you don’t accidentally lock yourself out of your own server. A typo in an IP address is all it takes. The good news is that, if you do lock yourself out, you still can gain access via the CloudAtCost Management Portal by clicking the Console button of your virtual machine. Because the console is on the physical machine and the lo interface is whitelisted, you can log in and disable the firewall temporarily: service iptables stop. Then fix the typo and restart the firewall: service iptables start.

First, let’s download the new IPtables config file into your root folder and take a look at it.

cd /root
wget http://incrediblepbx.com/iptables-lamp.tar.gz
tar zxvf iptables-lamp.tar.gz

Now edit the /root/iptables-lamp file by issuing the command: nano -w /root/iptables-lamp

You can scroll up and down through the file with Ctl-V and Ctl-Y. Cursor keys work as well. Once you make changes, save your work: Ctl-X, Y, ENTER. You’re now an expert with the nano text editor, an absolutely essential Linux tool.

Here’s what that file actually looks like:

*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
-A INPUT -p tcp -m tcp --tcp-flags ACK ACK -j ACCEPT
-A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
-A INPUT -p icmp -j DROP
-A INPUT -i lo -j ACCEPT
-A INPUT -p tcp ! --syn -m state --state NEW -j DROP
-A INPUT -m state --state INVALID -j DROP
-A INPUT -p tcp -m tcp --tcp-flags FIN,SYN,RST,PSH,ACK,URG NONE -j DROP
-A INPUT -p tcp -m tcp --tcp-flags SYN,FIN SYN,FIN              -j DROP
-A INPUT -p tcp -m tcp --tcp-flags SYN,RST SYN,RST              -j DROP
-A INPUT -p tcp -m tcp --tcp-flags FIN,RST FIN,RST              -j DROP
-A INPUT -p tcp -m tcp --tcp-flags ACK,FIN FIN                  -j DROP
-A INPUT -p tcp -m tcp --tcp-flags ACK,URG URG                  -j DROP
-A INPUT -p tcp -m set --match-set china src                    -j DROP
-A INPUT -p udp -m udp --dport 53 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 113 -j ACCEPT
-A INPUT -p udp -m udp --dport 123 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 123 -j ACCEPT
-A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT
#-A INPUT -s 12.34.56.78 -j ACCEPT
#-A INPUT -s yourFQDN.dyndns.org -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -j REJECT --reject-with icmp-host-prohibited
-A FORWARD -j REJECT --reject-with icmp-host-prohibited
COMMIT

Reminder: If you add another country to your block-china script, don’t forget to add a corresponding new country entry to your iptables file. See line 17 above that includes the word “china” for the syntax. There’s nothing much else to tweak except the two commented out (brown) lines that begin with #. First, remove the # symbol by moving the cursor to the right of the first one and hitting the backspace/delete key on your keyboard. Replace 12.34.56.78 with the public IP address of the computer from which you will be accessing your virtual machine. If you need multiple entries for multiple computers at different addresses, clone the line by pressing Ctrl-K and then Ctrl-U twice. Yes, we know. Some folks IP addresses change from time to time. In the next section, we’ll show you how to set up a Dynamic DNS entry with a utility that will keep track of your current IP address. In this case, uncomment the second commented line and replace yourFQDN.dyndns.org with your dynamic DNS address. Be very careful to assure that your FQDN is always on line. If the firewall cannot verify your DNS entry when it starts, the IPtables firewall will not start which means your server will be left unprotected. HINT: IP addresses are much safer because they are never verified.

Once you have your addresses configured, save the file: Ctl-X, Y, ENTER. Then issue the following commands to copy everything into place and restart the firewall.

mv /etc/sysconfig/iptables /etc/sysconfig/iptables.orig
cp -p /root/iptables-lamp /etc/sysconfig/iptables
echo "/etc/block-china.sh" >> /etc/rc.local
/etc/block-china.sh

Always, always, always check to be sure your firewall is functioning: iptables -nL. If you don’t see your desktop computer’s public IP address near the end of the listing, then the firewall is dead. status-lamp should also show IPtables down. Check for an error message which will tell you the problematic line so you can correct it.

Implementing Dynamic DNS Service on Your Virtual Machine

There are a number of free and paid Dynamic DNS providers. The way this works is you choose a fully-qualified domain name (FQDN) to identify your computer. Then you run a dynamic DNS update utility periodically from that computer. It reports back the current public IP address of your computer and your provider updates the IP address assigned to your FQDN if it has changed. In addition to supporting sites with ever changing IP addresses, it also allows you to permanently assign an FQDN to your computer or server so that it can be accessed without using a cryptic IP address.

If that computer happens to be an Incredible PBX server or a LAMP server that you’ve set up using this tutorial, then the following will get the DNS client update utility loaded using the RPM Forge repository that we previously installed:

yum --enablerepo=rpmforge install ddclient -y

Similar DNS update clients are available for Windows, Mac OS X, and many residential routers. Then it’s just a matter of plugging in the credentials for your dynamic DNS provider and your FQDN. In the case of the CentOS client, the config file is /etc/ddclient/ddclient.conf. Now reboot your server and pick up a good book on Linux to begin your adventure.

Now For Some Fun…

First, let’s check things out and make sure everything is working as it should. With your favorite web browser, visit the IP address of your new server. You should see the default Apache page:

Next, let’s be sure that PHP is working as it should. While still logged into your server as root using SSH or Putty, issue the following commands and make up some file name to replace test4567 in both lines. Be sure to keep the .php file name extension. Note to gurus: Yes, we know the second line below is unnecessary if you remove the space after the less than symbol in the first line. Unfortunately, WordPress forces the space into the display which left us no alternative.

echo "< ?php phpinfo(); ?>" > /var/www/html/test4567.php
sed -i 's|< |<|' /var/www/html/test4567.php

Now jump back to your web browser and access the new page you just created using the IP address of your server and the file name you made up: http://12.34.56.78/test4567.php

The PHPinfo listing will tell you everything you ever wanted to know about your web server setup including all of the PHP functions that have been enabled. That’s why you want an obscure file name for the page. You obviously don’t want to share that information with every bad guy on the planet. Remember. This is a public-facing web site that anyone on the Internet can access if they know or guess your IP address.

When you’re ready to set up your own web site, just name it index.php and store the file in the /var/www/html directory of your server. In the meantime, issuing the following command will assure that anyone accessing your site gets a blank page until you’re ready to begin your adventure:

echo " " > /var/www/html/index.php

Ready to learn PHP programming? There’s no shortage of books to get you started.

Adding WordPress to Your LAMP Server

Where to begin with WordPress? What used to be a simple platform for bloggers has morphed into an all-purpose tool that makes building virtually any type of web site child’s play. If you want to see what’s possible, take a look at the templates and sample sites shown on WPZOOM. Unless you’re an art major and savvy web designer, this will be the best $70 you ever spent. One of these templates will have your site up and running in minutes once we put the WordPress pieces in place. For the big spenders, $149 will give you access to over 50 gorgeous templates which you can download and use to your heart’s content on multiple sites. And, no, your sites don’t blow up after a year. You just can’t download any additional templates or updates unless you renew your subscription. The other alternative is choose from thousands of templates that are provided across the Internet as well as in the WordPress application itself.

WordPress templates run the gamut from blogs to newsletters to photographer sites to e-commerce to business portfolios to video to travel to magazines to newspapers to education to food to recipes to restaurants and more. Whew! There literally is nothing you can’t put together in minutes using a WordPress template. But, before you can begin, we need to get WordPress installed on your server. This is optional, of course. And, if you follow along and add WordPress, we’ve set it up in such a way that WordPress becomes the primary application for your site. Stated differently, when people use a browser to access your site, your WordPress template will immediately display. When we finish the basic WordPress setup and once you upload an image or two, you’ll have a site that looks something like this:

Before you begin, we strongly recommend that you acquire a domain for your site if you plan to use it for anything but experimentation. The reason is because it can be complicated to migrate a WordPress site from one location to another.2 Once you’ve acquired your domain, point the domain to the IP address of your new server. With a dirt cheap registrar such as Omnis.com, it’s easy:

Now let’s get started. To begin, we need to load the WordPress application onto your server:

cd /root
mkdir wordpress
cd wordpress
wget http://wordpress.org/latest.tar.gz
tar -xvzf latest.tar.gz -C /var/www/html

Next, we’ll configure MySQL to support WordPress. We’re assuming that you have NOT already created root passwords for MySQL. If you have, you’ll need to add -pYourPassword to the various commands below immediately after root. There is no space between -p and your root password. Also edit the first line and make up a new password (replacing XYZ below) for the wordpress user account that will manage WordPress on your server before you cut and paste the code:

mysql -u root -e 'CREATE USER wordpress@localhost IDENTIFIED BY "XYZ";'
mysql -u root -e 'CREATE DATABASE wordpress;'
mysql -u root -e 'GRANT ALL ON wordpress.* TO wordpress@localhost;'
mysql -u root -e 'FLUSH PRIVILEGES;'

Next, we need to configure WordPress with your new MySQL credentials. Before you cut and paste, replace XYZ in the fourth line with the password you assigned in the preceding MySQL step:

cp /var/www/html/wordpress/wp-config-sample.php /var/www/html/wordpress/wp-config.php
sed -i 's|database_name_here|wordpress|' /var/www/html/wordpress/wp-config.php
sed -i 's|username_here|wordpress|' /var/www/html/wordpress/wp-config.php
sed -i 's|password_here|XYZ|' /var/www/html/wordpress/wp-config.php
chown -R apache:apache /var/www/html/wordpress

Before you forget, take a moment and create a very secure password for your MySQL root user accounts. Here are the commands. Just replace new-password with your new password before you cut and paste. Note that you also will be prompted for this password when you execute the second command because you will now have a root user password in place from executing the first command.

/usr/bin/mysqladmin -u root password 'new-password'
/usr/bin/mysqladmin -u root -p -h localhost.localdomain password 'new-password'

Finally, we need to modify your Apache web server to support WordPress as the primary application. Be sure to enter your actual email address in the third line before you cut and paste the code below:

echo " " >> /etc/httpd/conf/httpd.conf
echo "<virtualhost *:80>" >> /etc/httpd/conf/httpd.conf
echo 'ServerAdmin somebody@somedomain.com' >> /etc/httpd/conf/httpd.conf
echo "DocumentRoot /var/www/html/wordpress" >> /etc/httpd/conf/httpd.conf
echo "ServerName wordpress" >> /etc/httpd/conf/httpd.conf
echo "ErrorLog /var/log/httpd/wordpress-error-log" >> /etc/httpd/conf/httpd.conf
echo "CustomLog /var/log/httpd/wordpress-acces-log common" >> /etc/httpd/conf/httpd.conf
echo "</virtualhost>" >> /etc/httpd/conf/httpd.conf
echo " " >> /etc/httpd/conf/httpd.conf
service httpd restart

That should do it. Open a browser and navigate to the IP address of your server. You should be greeted with the following form. Fill in the blanks as desired. The account you’re setting up will be the credentials you use to add and modify content on your WordPress site when you click Log In (as shown above). Make the username obscure and the password even more so. Remember, it’s a public web site accessible worldwide! When you click Install WordPress, you’ll be off to the races.

After your server whirs away for a minute or two, you will be greeted with the WordPress login prompt. With the username and password you entered above, you’ll be ready to start configuring your WordPress site.

Once you’re logged in, navigate to Appearance -> Themes and click Add New Theme. There’s you will find literally hundreds of free WordPress templates that can be installed in a matter of seconds if WPZOOM is too rich for your blood. For a terrific all-purpose (free) theme, try Atahualpa. We’ll leave our actual demo site running for a bit in case you want to explore and check out its performance. Installing and configuring the new theme took less than a minute:

A Final Word to the Wise. WordPress is relatively secure but new vulnerabilities are discovered regularly. Keep your templates, plug-ins, AND the WordPress application up to date at all times! The WordFence plug-in is a must-have. And we strongly recommend adding the following lines to your WordPress config file which then will let WordPress update everything automatically. Microsoft has given automatic updates a bad name, but in the case of WordPress, they work well.

echo "define('WP_AUTO_UPDATE_CORE', true);" >> /var/www/html/wordpress/wp-config.php
echo "add_filter( 'auto_update_plugin', '__return_true' );" >> /var/www/html/wordpress/wp-config.php
echo "add_filter( 'auto_update_theme', '__return_true' );" >> /var/www/html/wordpress/wp-config.php

Special Thanks: Our special tip of the hat goes to a few web sites that we found helpful in putting this article together especially Unixmen and Matt Wilcox & friends and Programming-Review.

Wondering What to Build Next with your new $10.50 Server in the Sky? Check out the latest Nerd Vittles tutorial. Turn it into a VoIP server FOR LIFE with free calling to/from the U.S. and Canada. Call for free demo:


Originally published: Monday, January 25, 2016





Need help with Asterisk? Visit the PBX in a Flash Forum.


 
Awesome Vitelity Special. Vitelity has generously offered a terrific discount for Nerd Vittles readers. You now can get an almost half-price DID from our special Vitelity sign-up link. If you’re seeking the best flexibility in choosing an area code and phone number plus the lowest entry level pricing plus high quality calls, then Vitelity is the hands-down winner. Vitelity provides Tier A DID inbound service in over 3,000 rate centers throughout the US and Canada. When you use our special link to sign up, Nerd Vittles gets a few shekels down the road to support our open source development efforts while you get an incredible signup deal as well. The going rate for Vitelity’s DID service is $7.95 a month which includes up to 4,000 incoming minutes on two simultaneous channels with terminations priced at 1.45¢ per minute. Not any more! For our users, here’s a deal you can’t (and shouldn’t) refuse! Sign up now, and you can purchase a Tier A DID with unlimited incoming calls and four simultaneous channels for just $3.99 a month. To check availability of local numbers and tiers of service from Vitelity, click here. NOTE: You can only use the Nerd Vittles sign-up link to order your DIDs, or you won’t get the special pricing! Vitelity’s rate is just 1.44¢ per minute for outbound calls in the U.S. There is a $35 prepay when you sign up. This covers future usage. Any balance is refundable if you decide to discontinue service with Vitelity.


Some Recent Nerd Vittles Articles of Interest…

  1. It doesn’t take long for the probing to begin. So watch your logs, look up the IP addresses to identify the countries, and block them unless you happen to be expecting visitors from that part of the world:
    [Sun Jan 24 00:36:12 2016] [error] [client 40.114.202.60] File does not exist: /var/www/html/wordpress/w00tw00t.at.blackhats.romanian.anti-sec:)
    [Sun Jan 24 00:36:12 2016] [error] [client 40.114.202.60] File does not exist: /var/www/html/wordpress/phpMyAdmin
    [Sun Jan 24 00:36:13 2016] [error] [client 40.114.202.60] File does not exist: /var/www/html/wordpress/phpmyadmin
    [Sun Jan 24 00:36:13 2016] [error] [client 40.114.202.60] File does not exist: /var/www/html/wordpress/pma
    [Sun Jan 24 00:36:13 2016] [error] [client 40.114.202.60] File does not exist: /var/www/html/wordpress/myadmin
    [Sun Jan 24 00:36:14 2016] [error] [client 40.114.202.60] File does not exist: /var/www/html/wordpress/MyAdmin
    [Mon Jan 25 00:29:29 2016] [error] [client 137.116.220.182] File does not exist: /var/www/html/wordpress/w00tw00t.at.blackhats.romanian.anti-sec:)
    [Mon Jan 25 00:29:29 2016] [error] [client 137.116.220.182] File does not exist: /var/www/html/wordpress/phpMyAdmin
    [Mon Jan 25 00:29:29 2016] [error] [client 137.116.220.182] File does not exist: /var/www/html/wordpress/phpmyadmin
    [Mon Jan 25 00:29:30 2016] [error] [client 137.116.220.182] File does not exist: /var/www/html/wordpress/pma
    [Mon Jan 25 00:29:30 2016] [error] [client 137.116.220.182] File does not exist: /var/www/html/wordpress/myadmin
    [Mon Jan 25 00:29:30 2016] [error] [client 137.116.220.182] File does not exist: /var/www/html/wordpress/MyAdmin
    []
  2. Should you ever have to migrate your WordPress site from one domain to another, here are two helpful tools to consider: the Automatic Domain Name Changer Plugin and the one we use, WordPress-Domain-Changer. []

Introducing the FUD-Free Firewall for FreePBX Distro and AsteriskNOW

After frequent complaints from our FreePBX® users, we introduced a firewall application for the PBX in a Flash™ and Incredible PBX™ platforms that protected FreePBX resources. That was over 5 years ago. The product became Travelin’ Man™ 3, an IPtables-based WhiteList that totally eliminated access to your Asterisk® server unless a WhiteList entry had been authorized by the administrator. The application was further embellished over the years to facilitate access by remote users. First, we introduced PortKnocker™ for Asterisk® and later we introduced Travelin’ Man 4 to let users call in with a passcode to authorize server access. For the past several years, a preconfigured firewall has been an integral component in what has become the 7-Layer Security Model included in all Incredible PBX builds. TIP: Security is not a new idea for us.

During this evolution, the FreePBX developers introduced their own distribution, the FreePBX Distro™. Conspicuously absent was a functioning firewall. We believed that the shortcoming would be remedied quickly. Hasn’t happened! In the meantime, a number of serious security vulnerabilities arose in the FreePBX product that compromised numerous servers running their distribution because of the absence of a functioning firewall. Digium® recently reintroduced AsteriskNOW™ as a clone of the FreePBX Distro. But still no firewall.

About a month ago, we decided to close the loophole for everyone’s security and develop a firewall for the only FreePBX-based distributions without a firewall, the FreePBX Distro and AsteriskNOW. Last week we began the rollout with a Nerd Vittles article explaining why this was essential, as if an explanation were necessary. Today, you get the GPL code.

Suffice it to say, our article was not well received. The usual Sangoma® players went into Damage Control Mode with what has become a predictable scenario whenever security issues are raised concerning the FreePBX design or vulnerabilities.

Meet The Sangoma 7.

  • The Good Cop: If only you’d purchase Genuine Sangoma Hardware, all of your security problems would disappear
  • The Bad Cop: Enjoy this nice Cup of FUD about your own distro which proves we’re all just alike
  • The Techie Cop: We thought of developing an open source firewall just the other day, and now you’re complaining
  • The Rest of “The Team”: Let the Astroturfing Begin… Retweet, favorite, and cheer for the brilliance of My 3 Cops

The Good Cop offered to solve all your security woes if you’d just buy (some more Sangoma) hardware.

The Bad Cop suggested that, with “cookie cutter security, you might as well hand out your password.” Just in case you have any doubts about whose approach has stood the test of time, let’s Google the FreePBX Security Vulnerability Track Record.

The Techie Cop claimed we had stolen his 2-day old idea to create an Open Source Firewall. Really?
Earth to Techie Cop: Where have you been for the past five years??

Funny stuff… if it weren’t so damaging to the Asterisk community and those trying to decide whether to put their faith in open source communications software.

Firewall Basics.

We’ve written dozens of articles on Asterisk security and firewall approaches so we won’t repeat all of the information. Here’s what you need to know. Software-based firewalls on Linux servers need to be integrated into the Linux kernel to be secure. IPtables is kernel-based and extremely reliable. Blacklist-based firewall designs, i.e. those that seek to identify the IP addresses of every bad guy on the planet don’t work very well. Bad guys aren’t stupid. They can do their damage by commandeering a little old lady’s Windows machine so you’re never going to collect all of the necessary “bad” IP addresses. They’re also smart enough to poison the blacklists with Internet resources you need such as DNS servers. So don’t waste your time with blacklists. WhiteLists work very well. You identify the IP addresses and FQDNs of all the Internet sites you need to support and all the SIP providers you wish to use. Nobody else even sees your server on the Internet. If the bad guys can’t see your server, they can’t attack it. Simple as that.

Travelin’ Man 3 WhiteList Tutorial.

Here are the fundamentals of the Travelin’ Man 3 design. We allow access from anybody and everybody on your private LAN. They still need a password to access FreePBX or to gain root access, but they can “see” your server. Private LAN addresses are non-routable over the Internet which means the bad guys can’t access your 192.168.0.4 IP address if you’re sitting behind a NAT-based hardware firewall. All of your internal phones will work with no firewall modifications. You may need to adjust these settings if you’re using a Cloud resource such as Amazon because they actually route non-routable IP addresses which would leave your server vulnerable without removing these entries (especially the 172 subnet for Amazon):

#-A INPUT -s 10.0.0.0/8 -j ACCEPT
#-A INPUT -s 172.16.0.0/12 -j ACCEPT
#-A INPUT -s 192.168.0.0/16 -j ACCEPT

Travelin’ Man 3 also authorizes access for certain mandatory services that are needed to keep your server operating properly. In addition, during installation, Travelin’ Man 3 whitelists localhost and the public and private IP addresses of your server as well as your PC or workstation. You obviously don’t want to lock yourself out of your own server.

As of today, Travelin’ Man 3 is primarily an IPv4 whitelist toolkit. IPv6 addresses are only supported to allow localhost access to your server. Any other IPv6 addresses must be added manually in /etc/sysconfig/ip6tables. We recommend not using FQDNs with IPv6 for the time being. And always restart IP6tables after adding new entries: service ip6tables restart.

You have the option of enabling the Incredible PBX collection of IP addresses used by many of the leading SIP providers around the world. Just run the enable-trusted-providers script in /root. The list of included providers is available here. You also have the option of adding (whitelisting) or deleting users’ and providers’ IP addresses and FQDNs yourself. Use the included scripts in the /root folder: add-ip, add-fqdn, and del-acct. For each account you set up, you get to define which access permission or combination of permissions will be available:

0 – ALL Services
1 – SIP (UDP)
2 – SIP (TCP)
3 – IAX
4 – Web
5 – WebMin
6 – FTP
7 – TFTP
8 – SSH
9 – FOP

Once you have made your selection, a user account will be created in /root with the name of the account and an extension of .iptables. Do NOT delete these files. They keep track of current IP addresses and accounts authorized for server access.

If you have remote users on the Internet, e.g. traveling salespeople, you can individually authorize access for them using a dynamic FQDN (add-fqdn) coupled with a dynamic DNS server that keeps IP addresses current as folks move around. Just load a dynamic DNS updater on their smartphone. Then plug the user entries into the included ipchecker script and execute a cron job on your server every few minutes to keep the FQDN entries refreshed. Simple.

echo "*/10 * * * * root /root/ipchecker > /dev/null 2>&1" >> /etc/crontab

IPtables does not directly support FQDN rules through the kernel. However, IPtables lets you configure your firewall rules using FQDNs which get translated into IP addresses whenever IPtables is restarted. The gotcha here is that, if an FQDN is not resolvable, IPtables fails to load, and you’re left with a vulnerable server. Travelin’ Man 3 takes care of this by employing a special restart script that temporarily disables unresolvable IP addresses.

The moral of the story:

ALWAYS USE iptables-restart TO RELOAD IPTABLES OR YOUR SERVER MAY END UP WITH NO FIREWALL!

We’ve also included support for a neat little trick that lets you whitelist remote SIP access to your server using a special FQDN. No further firewall adjustments are necessary. This is supported on most platforms except OpenVZ containers. The way this works is you first assign an obscure FQDN to your server’s IP address. It needs to be obscure because anyone with the FQDN gains SIP access to your server. But chances are pretty good that the bad guys will have a hard time figuring out that xq356jq.dyndns.org points to your server. You then can embed this FQDN in the SIP phone credentials for all of your remote users. The final step is to uncomment the last few lines in /etc/sysconfig/iptables after plugging in your obscure FQDN. Then restart IPtables: iptables-restart.

-A INPUT -p udp --dport 5060:5061 -m string --string "REGISTER sip:xq356jq.dyndns.org" --algo bm -j ACCEPT
-A INPUT -p udp --dport 5060:5061 -m string --string "REGISTER sip:" --algo bm -j DROP
-A INPUT -p udp --dport 5060:5061 -m string --string "OPTIONS sip:" --algo bm -j DROP

Finally, a word of caution about deploying Travelin’ Man 3 on the FreePBX Distro and AsteriskNOW platforms. We currently don’t have a vehicle in place to push security updates out to you as we do with Incredible PBX. This means you will have to remain vigilant to what’s happening in the telecommunications world and load updates yourself. You can stay current in a number of ways. We will post updates to this article in comments below so you can simply check back here periodically. An easier way to keep up with the latest security alerts and updates is to subscribe to the PBX in a Flash RSS Feed. This can be added to the FreePBX Status page by editing RSS Feeds in Settings -> Advanced Settings and adding:

http://pbxinaflash.com/rssfeed.xml

As you can see, there’s nothing “cookie cutter” about Travelin’ Man 3. It’s totally customizable to meet your own unique requirements. All we have done is tame IPtables and eliminate much of its complexity so that you can get a functional firewall up and running quickly. Now it’s deployment time!

Installing Travelin’ Man 3 for the FreePBX Distro & AsteriskNOW.

Log into your server as root from a desktop PC using SSH or Putty. This assures that you will have access from a device other than the console when you are finished. Then issue the following commands:

cd /root
wget http://incrediblepbx.com/tm3-firewall.tar.gz
tar zxvf tm3-firewall.tar.gz
./enable-iptables-whitelist

If you wish to enable the Incredible PBX trusted providers whitelist, issue the following command:

./enable-trusted-providers

ALWAYS use the following command to start or restart IPtables:

iptables-restart

NEVER use the following syntax with Travelin’ Man 3:

service iptables...

CHECK the status of your server at any time:

/root/status

The GPL Is NOT Dead: Coming Soon to FreePBX Distro and AsteriskNOW…

Stay tuned for Incredible PBX GUI, all of the GPL modules you know and love with NO NAGWARE and NO GOTCHAS. This also will assist users that got duped by the Sangoma offer to convert PBX in a Flash into a proprietary FreePBX Distro. After reading the Sangoma disclaimer about the script being donated by an anonymous user, ask yourself this question. When was the last time Sangoma republished code that they did not own or create themselves? Try NEVER.

BEFORE:

AFTER:

Originally published: Monday, August 10, 2015



Need help with Asterisk? Visit the PBX in a Flash Forum.


 
Awesome Vitelity Special. Vitelity has generously offered a terrific discount for Nerd Vittles readers. You now can get an almost half-price DID from our special Vitelity sign-up link. If you’re seeking the best flexibility in choosing an area code and phone number plus the lowest entry level pricing plus high quality calls, then Vitelity is the hands-down winner. Vitelity provides Tier A DID inbound service in over 3,000 rate centers throughout the US and Canada. When you use our special link to sign up, Nerd Vittles gets a few shekels down the road to support our open source development efforts while you get an incredible signup deal as well. The going rate for Vitelity’s DID service is $7.95 a month which includes up to 4,000 incoming minutes on two simultaneous channels with terminations priced at 1.45¢ per minute. Not any more! For our users, here’s a deal you can’t (and shouldn’t) refuse! Sign up now, and you can purchase a Tier A DID with unlimited incoming calls and four simultaneous channels for just $3.99 a month. To check availability of local numbers and tiers of service from Vitelity, click here. NOTE: You can only use the Nerd Vittles sign-up link to order your DIDs, or you won’t get the special pricing! Vitelity’s rate is just 1.44¢ per minute for outbound calls in the U.S. There is a $35 prepay when you sign up. This covers future usage. Any balance is refundable if you decide to discontinue service with Vitelity.


Some Recent Nerd Vittles Articles of Interest…

Firewalls 101: Why Every Asterisk Server Should Have a Functioning Firewall


Part of our fundamental disagreement with the FreePBX® design can be summed up in one word: FIREWALL or the lack of a functioning firewall in the FreePBX Distro and in the functionally identical Digium product, AsteriskNOW®.1 Most of the other design choices including the controversial, non-GPL compliant Module Signature Checking mechanism are touted as failsafe ways to detect altered systems even though changes in FreePBX MySQL tables and Asterisk config files can be modified easily without triggering alerts. In short, the Band-Aid® approach to module tampering does nothing to address the fundamental problem, prevention of unauthorized intrusions in the first place.

Some would contend that the included Fail2Ban product is specifically designed to prevent unauthorized intrusions by locking out the bad guys after a certain number of failed login attempts. Assuming Fail2Ban were functioning properly, which does not appear to be the case, putting all your eggs in the Fail2Ban basket also ignores several critical shortcomings in Fail2Ban. First, it has been documented that powerful servers such as Amazon EC2 and Twitter botnets give hackers almost unlimited intrusion attempts before Fail2Ban ever gets a time slice sufficient to scan logs for intrusion attempts. Second, Fail2Ban provides no protection against stealthy distributed bruteforcing activity. For example, if a botnet with 770,000 PCs attacked your server and each PC executed only two login attempts, Fail2Ban never gets triggered even assuming your server could handle the load and Fail2Ban got sufficient server resources to actually scan your logs. Finally, Fail2Ban provides no protection against Zero Day vulnerabilities where an intruder basically walks right into your server because of an unidentified vulnerability lurking in the existing code. Unfortunately, these are not hypothetical situations but regular occurrences over the past 10 years of Asterisk and FreePBX development. In a nutshell, that’s why you need a real firewall. It completely blocks all access to your server by unauthorized users all of the time.

Numerous companies have intentionally exposed Asterisk® servers to the public Internet in a continuing effort to identify problems before they affect “real servers.” We know of no similar efforts with a platform that includes FreePBX as an integral component of the server. Why? Because the potential for Zero Day Vulnerabilities in a platform of modular design is enormous. One vulnerable component in FreePBX and the entire house of cards collapses because of the blank check server access that a compromised FreePBX asterisk user account gives to an intruder. It’s the fundamental reason that services such as Apache were engineered to run with different user credentials than a root user in the real world. In essence, the current FreePBX design with Asterisk has elevated asterisk user credentials to allow root-like access to almost every server file and function with the exception of SSH access. And SSH access becomes all but unnecessary given the scope of the GUI functionality provided within FreePBX and the escalated privileges it enjoys.

On FreePBX-based Asterisk servers, the absence of any user account separation means Asterisk, Apache, and FreePBX services all operate under the single asterisk user account. If any piece collapses due to a vulnerability, the intruder gets the keys to the castle including read/write access to Asterisk and FreePBX manager credentials and config files as well as broad MySQL access. This, in turn, exposes your VoIP account credentials in addition to facilitating SQL injection into any and all FreePBX database tables. Because FreePBX “hides” numerous settings in over a hundred MySQL tables, the Asterisk DB, and dozens of Asterisk config files, once the asterisk user account access is compromised, many of the major components on your server could be cleverly reconfigured without leaving much of a hint that your server had been compromised. In fact, VoIP account credentials could be extracted and used elsewhere with no traceable footprint back to your server. For all you would know, your provider compromised your credentials rather than the other way around. Just another reminder that keeping a credit card on file for automatic replenishment with VoIP providers is a very bad idea!

Providing the asterisk user with these broad permissions was a (poor) design choice. Why was it done? To make it easy for the developers to alter virtually everything on your Asterisk server using FreePBX’s integrated Module Admin component. Root user permissions are never required to do much of anything other than server platform upgrades once the FreePBX Distro or AsteriskNOW product is installed. That’s exactly the design one would expect to find in a commercial, closed source software platform. But it’s unusual in the open source community to put it charitably. We trust we’ve made the case why a rock-solid firewall with any product that uses FreePBX modules is absolutely essential. FreePBX is a wonderful GUI, but use of the platform without a properly configured, fully functional firewall could be financially catastrophic not to mention the serious damage it could cause to others including the good reputation of Asterisk in the Internet community.

Our objective next week will be to help you implement a functioning Linux-based software firewall on the FreePBX Distro and AsteriskNOW platforms. It’s FREE! Not only will this improve the security of your server, but it will deny the bad guys a platform from which to launch mischievous acts against the rest of us. Unless you’re running Asterisk on a Cloud-based platform, do all of us a favor NOW! Run, don’t walk, to your nearest electronics store (including WalMart and BestBuy) and purchase one of the dozens of inexpensive NAT-based routers. Install it between the Internet and your server TODAY! This is the one we use, but there are plenty from which to choose including our refurbished one.2


NEWS FLASH:
Download the new FUD-Free Firewall for FreePBX Distro and AsteriskNOW.

Originally published: Monday, August 3, 2015




Need help with Asterisk? Visit the PBX in a Flash Forum.


 
Awesome Vitelity Special. Vitelity has generously offered a terrific discount for Nerd Vittles readers. You now can get an almost half-price DID from our special Vitelity sign-up link. If you’re seeking the best flexibility in choosing an area code and phone number plus the lowest entry level pricing plus high quality calls, then Vitelity is the hands-down winner. Vitelity provides Tier A DID inbound service in over 3,000 rate centers throughout the US and Canada. When you use our special link to sign up, Nerd Vittles gets a few shekels down the road to support our open source development efforts while you get an incredible signup deal as well. The going rate for Vitelity’s DID service is $7.95 a month which includes up to 4,000 incoming minutes on two simultaneous channels with terminations priced at 1.45¢ per minute. Not any more! For our users, here’s a deal you can’t (and shouldn’t) refuse! Sign up now, and you can purchase a Tier A DID with unlimited incoming calls and four simultaneous channels for just $3.99 a month. To check availability of local numbers and tiers of service from Vitelity, click here. NOTE: You can only use the Nerd Vittles sign-up link to order your DIDs, or you won’t get the special pricing! Vitelity’s rate is just 1.44¢ per minute for outbound calls in the U.S. There is a $35 prepay when you sign up. This covers future usage. Any balance is refundable if you decide to discontinue service with Vitelity.


Some Recent Nerd Vittles Articles of Interest…

  1. Technically, IPtables is running on the FreePBX Distro and AsteriskNOW platforms; however, it’s sole function is to act as the shutdown mechanism for Fail2Ban-detected breaches. It does not independently examine packets. There is no functioning iptables config file. From our vantage point, serving as the Fail2Ban traffic cop doesn’t qualify as a functioning firewall since it lacks any of the traditional IPtables rules that manage PREROUTING, INPUT, FORWARD, OUTPUT, and POSTROUTING of packets. []
  2. Where prices are competitive or availability is a factor, we often recommend Amazon because Amazon provides financial support to Nerd Vittles through our referral links. We encourage everyone to shop independently and purchase products from suppliers that best meet your own requirements. []

Firewalls and Internet Security: Separating FUD and Fiction in the VoIP World

Some of us have spent years developing secure VoIP solutions for Asterisk® that protect your phone bill while bringing Cloud-based solutions within reach of virtually anyone. So it’s particularly disappointing when a hardware manufacturer spreads fear, uncertainty, and doubt in order to peddle their hardware. In this case, it happens to be Session Border Controllers (SBCs). We want you to watch this latest “infomercial” for yourself:



To hear Sangoma tell it, every VoIP server protected by merely a firewall is vulnerable to endless SIP attacks unless, of course, you purchase an SBC. And since implementation of Cloud-based servers traditionally limits the ability to deploy an SBC, most Cloud-based VoIP solutions would become vulnerable to SIP attacks. In the words of Sangoma:

And with telecom fraud and PBX hacking on the rise, it’s important to keep your network secure. For most enterprises, it’s not a matter of if-but-when their [sic] network experiences an attack, potentially costing you valuable time and money.

Now Sangoma is touting an article in a blog from the U.K. that begins with the headline “Why Firewalls are not Enough.” The purported author is Jack Eagle, who is otherwise unidentified. Not surprisingly, the owner of the blog happens to be a reseller of Sangoma hardware. Here’s what Jack Eagle suggests:

In addition, the inherent function of firewalls is to deny all unsolicited traffic. Whereby, the act of making a phone call is an unsolicited event, thus, firewalls can be counterproductive to an effective VoIP deployment by denying VoIP traffic.

For the benefit of those of you considering a VoIP deployment either locally or in the Cloud using Asterisk, let’s cut to the chase and directly address some of the FUD that’s been thrown out there.

FUD #1: Internet SIP Access Exposes Asterisk to Attack

False. What is true is that unrestricted SIP access to your server from the Internet without a properly secured firewall may expose Asterisk to attack. Perhaps it’s mere coincidence but the only major Asterisk aggregation that still installs Asterisk with an unsecured firewall and no accompanying script, tutorial, or even recommendation to properly lock it down and protect against SIP attacks happens to be from the same company that now wants you to buy a session border controller.

FUD #2: Firewalls Aren’t Designed to Protect Asterisk from SIP Attacks

False. What is true is that the base firewall installation provided in the FreePBX® Distro does not protect against any attacks. In a Cloud-based environment or with local deployments directly exposed to the Internet, that could very well spell disaster. And it has on a number of occasions. The Linux IPtables firewall is perfectly capable of insulating your Asterisk server from SIP attacks when properly configured. With PBX in a Flash and its open source Travelin’ Man 3 script, anonymous SIP access is completely eliminated. The same is true using the tools provided in the latest Elastix servers. And, Incredible PBX servers have always included a secured firewall with simple tools to manage it. Of course, with local VoIP hardware and a hardware-based firewall, any Asterisk server can be totally insulated from SIP attacks whether IPtables is deployed or not. Just don’t open any ports in your firewall and register your trunks with your SIP providers. Simple as that.

FUD #3: SIP Provider Access to Asterisk Compromises Your Firewall

False. Registering a server with SIP or IAX trunk providers is all that is required to provide secure VoIP communications. Calls can flow in and out of your Asterisk PBX without compromising your server or communications in any way. Contrary to what is depicted in the infomercial, there is no need to poke a hole in your firewall to expose SIP traffic. In fact, we know of only one SIP provider that requires firewall changes in order to use their services. Simple answer: use a different provider. Consider how you access Internet sites with a browser from behind a firewall. The connection from your browser to web sites on the Internet can be totally secure without any port exposure in your firewall configuration. Registering a SIP trunk with a SIP provider accomplishes much the same thing. All modern firewalls and routers will automatically handle the opening and closing of ports to accommodate the SIP or IAX communications traffic.

FUD #4: Remote Users Can’t Access Asterisk Without SIP Exposure

False. Over the past several years, we have written about a number of methodologies which allow remote users to securely access an Asterisk server. That’s what Virtual Private Networks and Port Knocking and Remote Firewall Management are all about. All of these solutions provide access without exposing your server to any SIP vulnerabilities! We hope the authors of this infomercial will give these open source tools a careful look before tarnishing the VoIP brand by suggesting vulnerabilities which any prudent VoIP deployment can easily avoid without additional cost. Just use the right products!

Originally published: Thursday, April 23, 2015



Need help with Asterisk? Visit the PBX in a Flash Forum.


 
Awesome Vitelity Special. Vitelity has generously offered a terrific discount for Nerd Vittles readers. You now can get an almost half-price DID from our special Vitelity sign-up link. If you’re seeking the best flexibility in choosing an area code and phone number plus the lowest entry level pricing plus high quality calls, then Vitelity is the hands-down winner. Vitelity provides Tier A DID inbound service in over 3,000 rate centers throughout the US and Canada. When you use our special link to sign up, Nerd Vittles gets a few shekels down the road to support our open source development efforts while you get an incredible signup deal as well. The going rate for Vitelity’s DID service is $7.95 a month which includes up to 4,000 incoming minutes on two simultaneous channels with terminations priced at 1.45¢ per minute. Not any more! For our users, here’s a deal you can’t (and shouldn’t) refuse! Sign up now, and you can purchase a Tier A DID with unlimited incoming calls and four simultaneous channels for just $3.99 a month. To check availability of local numbers and tiers of service from Vitelity, click here. NOTE: You can only use the Nerd Vittles sign-up link to order your DIDs, or you won’t get the special pricing! Vitelity’s rate is just 1.44¢ per minute for outbound calls in the U.S. There is a $35 prepay when you sign up. This covers future usage. Any balance is refundable if you decide to discontinue service with Vitelity.


Some Recent Nerd Vittles Articles of Interest…

Knock Three Times: Pain-Free Remote Access to Your Asterisk or Linux Server

No. We’re not going to make you relive the 1970’s with us today although now you can listen to this Number 1 Hit and a million others for free with Amazon’s new Prime Music. No, we don’t get a commission if you sign up for Amazon Prime. Yes, we make millions when you buy something from Amazon using our links. Thank you! What we have for you today is a Number 1 Utility, and it works on virtually any Linux platform. If your fraternity or sorority had a secret knock to gain access, then you already know the basic concept. Port Knocker (aka knockd) from Judd Vinet is a terrific utility that runs as a daemon on your server and does just what you’d expect. It listens for knocks. When it detects three knocks on the correct three ports in the proper sequence and from the same IP address, it opens the IPtables Linux Firewall for remote access from that IP address to your server for a predefined period of time. This would allow you to log into your server with SSH or make SIP phone calls using a softphone registered to your remote Asterisk® server. What makes Port Knocker especially useful is the existence of knocking clients for virtually any smartphone, tablet, or desktop computer. For the Travelin’ Man, it’s another must have utility.

We introduced a turnkey implementation of Port Knocker in Incredible PBX for Ubuntu 14 late last week. If you were a pioneer earlier in the week, go back and install it again to take advantage of Port Knocker. Or better yet, follow along and we’ll show you how to install it on your own RedHat/CentOS or Ubuntu/Debian server in just a couple of minutes.

Prerequisites. We’ve built open source installation scripts for both the RedHat/CentOS platform as well as the Ubuntu/Debian operating systems. These knockd installers assume that you have a fully functional and locked down IPtables firewall with an existing WhiteList of authorized users. We’d recommend Travelin’ Man 3 if you need to deploy this technology and haven’t done so already. Last week’s Incredible PBX for Ubuntu 14 already includes Travelin’ Man 3 whitelisting technology. Read the article for full details.

Today’s knockd installers are fairly generic but, if you’re running a version of CentOS earlier than 6.x or Ubuntu earlier than 14 or Debian.anything, be advised that we haven’t tested these installers on those platforms so you’re on your own. Finally, if your server is sitting behind a hardware-based firewall (as we ALWAYS recommend), then you’ll also need to map the service you wish to access (e.g. UDP 5060 for SIP or TCP 22 for SSH) plus the three TCP ports from your hardware-based firewall to your server so that legitimate “knocks” can find their way to your server. The “knock” ports themselves do not need to be opened in your IPtables firewall configuration! We’re just knocking, not entering. :-)

Overview. As configured, today’s installation scripts will install and preconfigure knockd to load automatically when you boot up your server. Three random TCP ports will be assigned for your server, and this port sequence is what remote users will need to have in order to gain access. Yes, you can change almost everything. How secure is it? Well, we’re randomizing the 3-port knock sequence using over 3,900 ports so you can do the math to figure out the odds of a bad guy guessing the correct sequence. HINT: 3900 x 3900 x 3900. Keep in mind that these “knocks” must all be received from the same IP address within a 15-second window. So sleep well but treat the port sequence just as if it were a password. It is! Once a successful knock sequence has been received, the default Port Knocker configuration will open all ports on your server for remote access from the knocking IP address for a period of one hour. During this time, “The Knocker” can log in using SSH or make SIP calls using trunks or extensions on the server. Port Knocker does not alleviate the need to have legitimate credentials to log into your server. It merely opens the door so that you can use them. At the bewitching (end of the) hour, all ports will be closed for this IP address unless “The Knocker” adds a whitelist entry for the IP address to IPtables during the open period. Yes, all of this can be modified to meet your individual requirements. For example, the setup could limit the range of ports available to “The Knocker.” Or the setup could leave the ports open indefinitely until another series of knocks were received telling knockd to close the IPtables connection. Or perhaps you would want to leave the ports open for a full day or a week instead of an hour. We’ll show you how to modify all of the settings.

Server Installation. To get started, log into your server as root and download and run the appropriate installer for your operating system platform.

For RedHat/Fedora/CentOS/ScientificLinux servers, issue the following commands:

cd /root
wget http://nerdvittles.com/wp-content/knock-R.tar.gz
tar zxvf knock*
rm knock-R.tar.gz
./knock*

For Ubuntu/Debian servers, issue the following commands:

cd /root
wget http://nerdvittles.com/wp-content/knock-U.tar.gz
tar zxvf knock*
rm knock-U.tar.gz
./knock*

For ARM-based servers, issue the following commands:

cd /root
wget http://nerdvittles.com/wp-content/knock-ARM.tar.gz
tar zxvf knock*
rm knock-ARM.tar.gz
./knock*

Server Navigation Guide. On both the RedHat/CentOS/Fedora and Ubuntu/Debian platforms, the knockd configuration is managed in /etc/knockd.conf. Before making changes, always shutdown knockd. Then make your changes. Then restart knockd. On RedHat systems, use service knockd stop and start. On Ubuntu, use /etc/init.d/knockd stop and start. By default, knockd monitors activity on eth0. If your setup is different, on Ubuntu, you’ll need to change the port in /etc/default/knockd: KNOCKD_OPTS="-i wlan0". On RedHat, the config file to modify is /etc/sysconfig/knockd and the syntax: OPTIONS="-i venet0:0".

In /etc/knockd.conf, create an additional context to either start or stop an activity. It can also be used do both as shown in the example code above. More examples here. There’s no reason these activities have to be limited to opening and closing the IPtables firewall ports. You could also use a knock sequence to turn on home lighting or a sprinkler system with the proper software on your server.

To change the knock ports, edit sequence. Both tcp and udp ports are supported. seq_timeout is the number of seconds knockd waits for the complete knock sequence before discarding what it’s already received. We’ve had better luck on more servers setting tcpflags=syn. start_command is the command to be executed when the sequence matches. cmd_timeout and stop_command tell knockd what to do after a certain number of seconds have elapsed since the start_command was initiated. If you’re only starting or stopping some activity (rather than both), use command instead of start_command and stop_command to specify the activity.

IPtables 101. The default setup gives complete server access to anyone that gets the knock right. That doesn’t mean they get in. In the PIAF World, it means they get rights equivalent to what someone else on your LAN would have, i.e. they can attempt to log in or they can use a browser to access FreePBX® provided they know the server’s root or FreePBX credentials.

If you would prefer to limit access to a single port or just a few ports, you can modify command or start_command and stop_command. Here are a few examples to get you started.

To open SSH access (TCP port 22):

/sbin/iptables -A INPUT -s %IP% -p tcp --dport 22 -j ACCEPT

To close SSH access (TCP port 22):

/sbin/iptables -D INPUT -s %IP% -p tcp --dport 22 -j ACCEPT

To open a range of SIP ports (UDP 5060 to 5069):

/sbin/iptables -A INPUT -s %IP% -p udp --dport 5060:5069 -j ACCEPT

To close a range of SIP ports (UDP 5060 to 5069):

/sbin/iptables -D INPUT -s %IP% -p udp --dport 5060:5069 -j ACCEPT

Here’s a gotcha to be aware of. If you’re using the Travelin’ Man 3 WhiteList setup on your server, be especially careful in crafting your IPtables rules so that you don’t accidentally remove an existing Travelin’ Man 3 rule in closing some port with knockd. You will note that the syntax of the knockd commands is intentionally a bit different than what you will find in your Travelin’ Man 3 setup. This avoids clobbering something accidentally.

Monitoring Activity. Here are the two best tools to monitor knockd activity to make certain your setup is performing as expected. The knockd log (/var/log/knockd.log) will tell you when a knocking attempt has occurred and whether it was successful:
[2014-07-06 14:44] starting up, listening on eth0
[2014-07-06 15:29] 79.299.148.11: opencloseSSH: Stage 1
[2014-07-06 15:29] 79.299.148.11: opencloseSSH: Stage 2
[2014-07-06 15:29] 79.299.148.11: opencloseSSH: Stage 3
[2014-07-06 15:29] 79.299.148.11: opencloseSSH: OPEN SESAME
[2014-07-06 15:29] opencloseSSH: running command: /sbin/iptables -A INPUT -s 79.299.148.11 -p tcp --dport 22 -j ACCEPT

Next, verify that the IPtables command did what it was supposed to do. iptables -nL will tell you whether port 22 access was, in fact, enabled for 79.299.148.11. The entry will appear just above the closing Chain entries in the listing:

ACCEPT     tcp  --  79.299.148.11         0.0.0.0/0           tcp dpt:22

Two things typically can go wrong. Either the knock from a client computer or cellphone wasn’t successful (knockd.log will tell you that) or IPtables didn’t open the port(s) requested in your knockd command (the iptables -nL query will show you that). In the latter case, it’s usually a syntax error in your knockd command. Or it could be the timing of the knocks. See /var/log/knockd.log.

Port Knocker Clients. The idea behind Port Knocker is to make remote access easy both for system administrators and end-users. From the end-user perspective, the simplest way to do that is to load an app on the end-user’s smartphone so that even a monkey could push a button to gain remote access to a server. If the end-user’s cellphone has WiFi connectivity sitting behind a firewall in a hotel somewhere, then executing a port knock from the smartphone should open up connectivity for any other devices in the hotel room including any notebook computers and tablets. All the devices typically will have the same public IP address, and this is the IP address that will be enabled with a successful knock from the smartphone.

Gotta love Apple’s search engine. Google, they’re not…

There actually are numerous port knocking clients for both Android and iOS devices. Here are two that we’ve tested that work: PortKnock for the iPhone and iPad is 99¢ and PortKnocker for Android is free. Some clients work better than others, and some don’t work at all or work only once. DroidKnocker always worked great the first time. Then it wouldn’t work again until the smartphone was restarted. KnockOnD for the iPhone, which is free, worked fine with our office-based server but wouldn’t work at all with a cloud-based server at RentPBX. With all the clients, we had better results particularly with cloud-based servers by changing the timing between knocks to 200 or 500 milliseconds. How and when the three knocks are sent seems to matter! Of all the clients on all the platforms, PortKnocker was the least temperamental and offered the most consistent results. And you can’t beat the price. A typical setup is to specify the address of the server and the 3 ports to be knocked. Make sure you have set the correct UDP/TCP option for each of the three knocks (the default setup uses 3 TCP ports), and make sure the IP address or FQDN for your server is correct.

Another alternative is to use nmap to send the knocks from a remote computer. The knock.FAQ file in your server’s /root directory will tell you the proper commands to send to successfully execute a connection with your server’s default Port Knocker setup. Enjoy!

Originally published: Monday, July 7, 2014


Support Issues. With any application as sophisticated as this one, you’re bound to have questions. Blog comments are a terrible place to handle support issues although we welcome general comments about our articles and software. If you have particular support issues, we encourage you to get actively involved in the PBX in a Flash Forums. It’s the best Asterisk tech support site in the business, and it’s all free! Please have a look and post your support questions there. Unlike some forums, ours is extremely friendly and is supported by literally hundreds of Asterisk gurus and thousands of users just like you. You won’t have to wait long for an answer to your question.



Need help with Asterisk? Visit the PBX in a Flash Forum.


 
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