Monthly Archives: April 2007

Here we go again to patch another denial of service problem and some SIP vulnerabilities with Asterisk®. All versions are apparently affected. We obviously can't provide step-by-step instructions for each and every version of Asterisk@Home and TrixBox. But we have thousands of loyal readers that depend upon TrixBox 1.2.3 systems in a production environment. So today's column is for these folks. Our special thanks to Bubba for lending a technical hand as well. We've tested this pretty carefully on Nerd Vittles editions of TrixBox 1.2.3. That includes PBX-in-a-Flash implementations on Linux systems as well as Nerd Vittles VMware builds of TrixBox 1.2.3 which run on Windows and Mac desktop systems. If you're running a different system, you'll have to read between the lines and do the best you can. It reportedly works fine to upgrade Trixbox 2.x sysems as well. If you really get stumped, post your questions on the TrixBox forums and someone will come to your rescue. Make a backup of your system before you begin. For an excellent free backup solution, visit Thomas King's site for Backup 2 and follow the instructions.

The Asterisk Security Problem. Today's issues are well documented on the asterisk-announce mailing list. You can read the archive here. Incidentally, for those that didn't know it, we've provided a convenient link to all of the Asterisk mailing list archives in the right column. Just click on Asterisk ListServ. New versions of both Asterisk and Zaptel are now available, and today we'll show you how to apply the upgrade to Nerd Vittles TrixBox 1.2.3 systems.

Getting the Latest Kernel Source for TrixBox. TrixBox systems don't ship with kernel source code so we have to begin there before we have the necessary pieces in place to compile the new version of Asterisk and Zaptel. Log into your Asterisk server as root and issue the following command:

Addressing the RedHat Bug. Every time there is an update using the Asterisk kernel, module support needs to be rebuilt using the new kernel. Unfortunately, a RedHat bug (inherited by CentOS) causes the rebuilding process to fail. Here's the fix. Log into your new server as root and issue the following commands to determine which new kernel source was loaded on your system:

cd /usr/src/kernels
ls

You should see an entry that looks something like this: 2.6.9-34.0.2.EL-something. Depending upon the processor in your system, the something may be different than our machine. Write down the name of the new kernel directory and substitute it below for 2.6.9-34.0.2.EL-i686. Now issue these commands:

cd /usr/src/kernels/2.6.9-34.0.2.EL-i686/include/linux
mv spinlock.h spinlock.h.old
wget http://nerdvittles.com/trixbox/spinlock.h
shutdown -r now


Fixing Some Source Code Wrinkles. At least one of the existing (older) source modules in the TrixBox 1.2.3 build will cause Asterisk to fail to restart after updating Asterisk. The simple fix below solved it for us. Your mileage may vary. If you have problems, look at the tail of the Asterisk error log (tail /var/log/asterisk/full) and then find the offending source module in the directory shown below. Rename the module and try the compiles again. Here's the error we received (app_speech_utils.so: Asterisk died with code 1.) and what solved it for us without breaking anything (actually it apparently does break Lumenvox; review Comment #7 in our previous security column for how to fix it):

cd /usr/lib/asterisk/modules
mv app_speech_utils.so app_speech_utils.so.old


It also has been reported that some versions of TrixBox may no longer function without adding the openssl-devel module. Thanks to David Josephson for the heads up.

yum install openssl-devel


Installing Asterisk 1.2.18 and Zaptel 1.2.17 and AddOns 1.2.6. Now we're ready to install the updates. While still logged in as root, execute the following commands in order:

amportal stop

shutdown -r now


Now rebuild support for your ZAP devices or ztdummy if you have no ZAP devices. Log in as root again and type the following command: rebuild_zaptel. Then reboot your system: shutdown -r now. Now log in as root again. If you have zaptel devices, type modprobe wcfxo. Whether you have zaptel devices or not, type amportal stop and then genzaptelconf. Reboot your system again, and you should be back in business.

freePBX Cleanup. For some reason, these security updates cause some minor problems with the freePBX configuration. Some users report that Music on Hold stops functioning while others have indicated that the introductory prompt for voice mail stops functioning. Both fixes are simple. Here's how.

For the Music on Hold problem, open freePBX with your web browser. Click MusicOnHold, then click Default under the Add Music Category listing. Now click Enable Random Play button, and click the Red Bar to reload Asterisk.

For the introductory voice prompt with voice mail, click General Settings. The fifth option on the page is Direct Dial to VoiceMail Message Type. Change the setting from Default to Unavailable. Save your change and click the Red Bar to reload Asterisk. You should have smooth sailing after these tweaks. Enjoy!

Securing AsteriDex. If you have a preconfigured TrixBox system that includes our very own AsteriDex, you'll need to download and install this simple patch to resolve a security vulnerability that was discovered. Log into your Asterisk server as root and issue the following commands:

cd /var/www/html/asteridex
rm -f callboth.php
wget http://nerdvittles.com/trixbox11/callboth.zip
unzip callboth.zip
rm -f callboth.zip
chown asterisk:asterisk callboth.php
chmod 775 callboth.php


Nerd Vittles Demo Hot Line (courtesy of les.net). You now can take a number of Nerd Vittles projects for a test drive... by phone! The current demos include (1) MailCall for Asterisk with password 1111 (retrieve your email by phone), (2) NewsClips for Asterisk (latest news headlines in dozens of categories), (3) Weather Forecasts by U.S. Airport Code, and (4) Weather Forecasts by U.S. ZIP Code. You're not prompted for #4 yet, but it does work! Just call our number (shown in the left margin) and take any or all of them for a spin. The sound quality may not be perfect due to performance limitations of our ancient Intel 386 demo machine. But the price is right.

Nerd Vittles Fan Club Map. Thanks for visiting! We hope you'll take a second and add yourself to our Frappr World Map compliments of Google. In making your entry, you can choose an icon: guy, gal, nerd, or geek. For those that don't know the difference in the last two, here's the best definition we've found: "a nerd is very similar to a geek, but with more RAM and a faster modem." We're always looking for the best BBQ joints on the planet. So, if you know of one, add it to the map while you're visiting as well.

Some Recent Nerd Vittles Articles of Interest...

Last year's demise of Kelly Pickler prompted us to put on our programming hat to conquer FOX TV® network's American Idol® and this year they've destroyed the singing career of poor Sanjaya Malakar. You'll have to agree that there's nothing quite as mind numbing as an hour of American Idol and 50 of your favorite commercials. As if that weren't enough, they expect you to sit by your telephone for TWO FOUR HOURS voting for your hero after the commercials end.

Since our original release of The Idolizer, much has changed. Not only are there new contestants, but now there's freePBX and TrixBox. Enter, The Idolizer II. So today's Asterisk® project is for those that have better things to do than dialing a tollfree number for two hours every Tuesday evening now that we're getting down to the wire on American Idol. And, no, the show's producers don't like autodialers. We don't like commercials (especially ten at a time), but they're still showing those. So here's the deal. Cut out the commercials, and we'll turn off our autodialer. And we'd bet DialIdol.com will, too. And, no, we're not affiliated with the Fair and Balanced® network nor the American Idol® show. We just don't want to waste two hours dialing the same phone number over and over ... when we could be doing our Honey-Do's to make the Little Mrs. happy.

Prerequisites. To use The Idolizer II autodialer with Asterisk, you'll need a free TrixBox PBX or at least a copy of the VMware version of TrixBox 1.2.3 for Windows or a Mac. Both run in a window on your desktop machine of choice. This works on any version of TrixBox or a plain Asterisk system running a current version of freePBX. Our tutorial will get you up and running in under an hour. Then you'll need an account with a hosting provider that gives you free calls to toll-free numbers or unlimited outbound calling in the U.S.

Installation. Using a web browser, open the TrixBox Control Panel and choose System Administration->Config Edit->extensions_trixbox.conf and add the following custom context to the bottom of the file:

[custom-idolizer]
exten => s,1,SetGlobalVar(COUNTER=1)
exten => s,2,Answer
exten => s,3,Wait(2)
exten => s,4,Dial(sip/8664365701@telasip-gw|18|L(10000:2000:5000)) ; 18 for TelaSIP, 22 for FWD
;exten => s,4,Dial(iax2/*18664365701@fwd|22|L(10000:2000:5000)) ; 18 for TelaSIP, 22 for FWD
exten => s,5,Goto(h,1)
exten => s,105,NoOp(BUSY)
exten => s,106,Goto(h,1)
exten => h,1,SetGlobalVar(COUNTER=$[${COUNTER} + 1])
exten => h,2,NoOp(Counter: ${COUNTER})
exten => h,3,Wait(6)
exten => h,4,GotoIf($["${COUNTER}" < "999"]?s,2) exten => h,5,Hangup

Once you know the phone number of the contestant you wish to vote for, make the following adjustments to the code above:

Now move to the top of the file and insert the following code in the [from-internal-trixbox] context using an available extension number on your system (default=4365 which spells I-D-O-L on your trusty Asterisk telephone):

exten => 4365,1,Goto(custom-idolizer,s,1)


Click the Update button to save your changes. Now open freePBX and choose Setup->Misc Destinations. For the Description, enter Idolizer II. For the Dial entry, type 4365. Click Submit Changes and then the Red Bar to reload your Asterisk settings.

Tweaking the Settings. If you find that your calls aren't being completed or that your votes aren't being registered (i.e. the call disconnects before you are thanked for voting), it's easy to fine tune the script. The number 18 in s,4 tells the dialer how many seconds to wait for an answer when placing calls. The number 10000 in s,4 (in thousandths of a second) tells Asterisk how long to stay connected once a call is answered. And the number 6 in h,3 tells Asterisk how many seconds to wait between placing calls. After making changes, log into your server as root and type: amportal restart.

Using the AutoDialer. When you're ready to begin your dialing spree, pick up an extension on your system and dial the extension number you assigned to The Idolizer II. Remember, the default number is 4365. Put the receiver down (don't hang up!) and enjoy the rest of your evening while The Idolizer II does the dialing for you. When you're ready to stop voting, hang up the phone. If you'd like to follow the progress of your calls, fire up the Command Line Interface (CLI) on your Asterisk system (asterisk -rvvvvv) after logging in as root. Enjoy the show!

The Year of Flash. If you're a slow learner like us, be glad you waited until now to tackle Adobe's Flash technology. The unbelievably simple tools that are now available to build Flash applications are nothing short of mind-boggling. We've been prototyping some of this technology for a new neighborhood web site. Have a look at this link, and click around the various Flash applets. We built it all from nothing in UNDER 3 HOURS! They look almost as good as Apple's Dashboard Widgets except they'll run on any platform: Windows, Mac, or Linux. All you need is a current web browser with a Flash Player to run these babies. Internet Explorer, Firefox, and Safari all work just fine. If you want to do a little experimenting, here's the deal of the year. The best flash tools on the planet are made by CoffeeCup Software. A close runner-up is Amara Software. You can visit their sites and get free demos to try out. Then you can buy all the tools from CoffeeCup for about $700 or from Amara for $129... or you can sign up for a year of hosting with Lunarpages and get every single CoffeeCup application for free. And, just so you don't feel totally ripped off by the one-year web hosting fee of $84, Lunarpages throws in support for 10 domains, 250 gigs of storage space, 2.5 terabytes of monthly bandwidth, and a free domain registration for as long as you host with them. Use the coupon code blog25 when you sign up to save an additional $25. That makes the total cost $59 for all you math wizards. Our site link to the Flash Widgets is actually hosted at Lunarpages so you can judge the performance for yourself. If you want them to back up your data every night and restore any or all files from a backup at any time, add another whopping $1.50 a month. Yes, we get a spiff if you sign up using our link. Sure beats clicking on the Donate button, doesn't it? And, if you happen to work in a K/12 school, the deal is even sweeter: the web hosting is free and so are five of the very best CoffeeCup Software applications. Now go learn something new or, better yet, teach it to a kid!

Nerd Vittles Demo Hot Line (courtesy of les.net). You now can take a number of Nerd Vittles projects for a test drive... by phone! The current demos include (1) MailCall for Asterisk with password 1111 (retrieve your email by phone), (2) NewsClips for Asterisk (latest news headlines in dozens of categories), (3) Weather Forecasts by U.S. Airport Code, and (4) Weather Forecasts by U.S. ZIP Code. You're not prompted for #4 yet, but it does work! Just call our number (shown in the left margin) and take any or all of them for a spin. The sound quality may not be perfect due to performance limitations of our ancient Intel 386 demo machine. But the price is right.

Nerd Vittles User Map. Thanks for visiting! We hope you'll take a second and add yourself to our Frappr World Map. In making your entry, you can choose an icon: guy, gal, nerd, or geek. For those that don't know the difference in the last two, here's the best definition we've found: "a nerd is very similar to a geek, but with more RAM and a faster modem." The map still isn't quite representative of where all of our visitors are coming from, but we're getting there. We're always looking for the best BBQ joints on the planet. So, if you know of one, add it to the map while you're visiting as well. We'll check it out one of these days.

Some Recent Nerd Vittles Articles of Interest...

My in-law’s once-removed (see if you can figure that one out) chartered one of the finest cruise ships on the planet last week to take 200 of their closest friends on a seven-day cruise in the Caribbean. Do you have 200 close friends?? If you’ve watched the movie Speed 2: Cruise Control, you’ve seen this ship up close. They chartered the ship for several months to make the movie. There were actually 197 passengers and 179 crew on the ship for our cruise so life was pretty good… for a week. Now I’m cooking my own breakfast again. We were lucky enough to squeak onto the invitation list for the bottom deck. Actually, there was no bottom deck. Every room was palatial with digital TV, a DVD Player, thousands of free DVD movies, unlimited booze, slot machines, and… Well, you get the idea.

For those that live and breathe technology (like we do), I thought you might enjoy a brief technical update on cruising as it pertains to Internet and telephony use, especially Asterisk® and Skype. We set sail in St. Thomas for the West Indies with stops in Antigua, St. Martin, Virgin Gorda, and Nassau before returning to Fort Lauderdale. You can click on the photo to visit our Photo Gallery if photography happens to be one of your pastimes or if you just want to see what you missed.

Cruising and the Internet. Those two big round balls you see on the top deck of the Seabourn Legend are actually antennas that provide Internet service via satellite 24/7. We’re accustomed to Comcast’s 8 megabit service in Charleston, and it’s not quite that good. But it’s pretty damn fast. That’s the good news. The not so good news is that it’s still expensive, and the bandwidth is shared between Internet surfers and those wishing to make phone calls from the ship. Phone calls from the ship are $4.95 a minute, and Internet service via a ship-wide Wi-Fi HotSpot is $25 an hour. As you might imagine, while others were soaking up the sun, I was quizzing the Captain and Hotel Manager about unlimited service, cost, bandwidth, and better telephony solutions. They were very attentive. This technology is less than a year old. While there have been other providers for several years, reliability has been pretty terrible until now. As with any Internet service provider, the next step is figuring out how much bandwidth you actually need and whether it is cost effective to implement all-you-can-eat Internet service. Disney and some of the other big ships already have it, but 3,000 people sharing a satellite link is not exactly broadband at its finest. Seabourn, on the other hand, has ships that are technology marvels in and of themselves, and they want nothing less than the best Internet experience for every one of their 200 passengers. I’d give it one more year unless you have deep pockets. And, after signing up for a Seabourn cruise, you probably won’t.

Once we got past the sticker shock of $25 an hour Internet service, Plan B was to figure out a way to use Asterisk or Skype to beat the $4.95 a minute telephony charges. After all, even at $25 an hour, that works out to just over 40¢ a minute which is less than one-tenth the cost of their telephony offering. More bad news unfortunately. The service provider who set up the system has locked down all ports except port 80. Yes, Skype and Asterisk can live with port 80, but all of the UDP ports were blocked as well so home-grown IP telephony was pretty much dead. According to the hotel manager, they will unlock other ports as soon as they get the system stabilized. And unlimited Internet service is also on the drawing board. The temporary high cost is designed primarily to discourage heavy usage until they can put sufficient bandwidth in place to support the 10% of passengers who will probably use it.

Cellphone Service Onboard Ship. Seabourn is about half way through providing transparent cellphone service onboard every one of their ships all the time. The only prerequisitie is a GSM phone which left our Sprint service dead in the water, literally. Many onboard with Cingular service made and received calls regularly, and their Blackberrys had no trouble receiving and sending messages. Just wait until they get home and discover that all those calls were billed at $2.95 or more per minute. Roaming outside the U.S. isn’t included in any U.S. cellphone plans that we know of. Until Skype or Asterisk work, the real key to inexpensive telephone calls while cruising the world is to buy an unlocked Quadband GSM phone and then purchase a local SIM card at each destination. They are readily available within 100 yards of the dock so don’t bother to take one with you. If you don’t own an unlocked GSM phone, you can even rent one for about $35 a week. If you’d prefer to purchase a SIM card in advance of your trip, use Google to search for the country of interest: free incoming calls gsm sim card "antigua". Once known only for its postage stamps, the Principality of Liechtenstein has become the SIM card mecca of the universe, much like what Iowa has done for free international calling from the United States.

Using the One Ringy-Dingy Phone Trick. Be sure you purchase a local SIM card that includes free incoming calls. Why? Because you then can use Nerd Vittles’ One Ringy-Dingy Phone Trick to call your home Asterisk system from your new GSM phone, let it ring once, hang up, and let your Asterisk system call you back with outbound dialtone using DISA. Actually, this has gotten considerably easier since our original article 18 months ago. Newer versions of freePBX include a Callback option which does all the work for you without writing a single line of code:

If you want a more flexible SIM card that works in most countries with low-cost inbound calls, try a service such as United Mobile. Their incoming call rates for Antigua from the U.S. are 19¢ a minute. In 80 countries whose territory doesn’t look like an Island, the incoming calls are free. Doing the math, you’d pay 19¢ a minute for the inbound cell call plus your Asterisk rate from your U.S.-based Asterisk server to your assigned cellphone number from United Mobile. That total will almost always be considerably less than the outbound U.S. calling rate on your SIM card.

If you have additional telephony tips for those traveling around the globe, feel free to leave a comment and share it with our readers. Enjoy your cruise! We did.

Nerd Vittles Demo Hot Line (courtesy of les.net). You now can take a number of Nerd Vittles projects for a test drive… by phone! The current demos include (1) MailCall for Asterisk with password 1111 (retrieve your email by phone), (2) NewsClips for Asterisk (latest news headlines in dozens of categories), (3) Weather Forecasts by U.S. Airport Code, and (4) Weather Forecasts by U.S. ZIP Code. You’re not prompted for #4 yet, but it does work! Just call our number (shown in the left margin) and take any or all of them for a spin. The sound quality may not be perfect due to performance limitations of our ancient Intel 386 demo machine. But the price is right.

Nerd Vittles Fan Club Map. Thanks for visiting! We hope you’ll take a second and add yourself to our Frappr World Map compliments of Google. In making your entry, you can choose an icon: guy, gal, nerd, or geek. For those that don’t know the difference in the last two, here’s the best definition we’ve found: "a nerd is very similar to a geek, but with more RAM and a faster modem." We’re always looking for the best BBQ joints on the planet. So, if you know of one, add it to the map while you’re visiting as well.