Tech Debug » Musings

Fixed iChat AV thru OpenBSD PF Firewall

lantrix — Thu, 14 Jan 2010 01:41:08 +0000

This has been bugging me for ages, but the fix is so simple.
I use OpenBSD for my router, and have PF (Packet Filter) running the firewall and NAT rules.

I have previously setup the port forwarding, etc. according to Apple, but never could get a successful connection using video or audio (or screen sharing).

After reading a post on the OpenBSD misc mailing list I went back and read the OpenBSD 4.5 pf.conf man page.

There is a section of the man page that states (my emphasis):

fragment reassemble
Using scrub rules, fragments can be reassembled by normalization.
In this case, fragments are buffered until they form a complete
packet, and only the completed packet is passed on to the filter.
The advantage is that filter rules have to deal only with complete
packets, and can ignore fragments. The drawback of caching frag-
ments is the additional memory cost. But the full reassembly
method is the only method that currently works with NAT. This is
the default behavior of a scrub rule if no fragmentation modifier
is supplied.

My scrub settings were such that I was filtering not complete packets, but fragments. The moment I changed the scrub settings to this:
scrub in on $ext_if all fragment reassemble

All worked perfect. I can initiate iChat calls and receive them too. Desktop sharing now works as well. All using Google talk (jabber) in iChat.

Note that in OpenBSD 4.6 or current there have been PF changes, so the wording of the scrub rule may be different. Always read the pf.conf man page for the release you are on.

Server Migration Complete

lantrix — Tue, 19 May 2009 16:40:44 +0000

Thanks for your patience whilst I’ve been offline, and stick around!
I’ve moved off a vm infrastructure back to a real server that I’m in control of.

Translation for the Mac by Kavasoft

lantrix — Fri, 05 Dec 2008 07:25:25 +0000

About 24 months ago I purchased a version of KavaSoft’s Translation Service application for the Mac. With the recent move from my old Powerbook to my new MacBookPro the application stopped working. Apparently the licence is tied not just to your purchase but to the computer you installed it on.

As I had used the Apple migration tool to move everything across to the new laptop, Translation Service stopped working. I dropped an email to the developer and literally got an email response 60 minutes later with an updated licence.

Now that’s customer service! There is nothing like a Mac application developer to renew your faith in customer service. After dealing with so many large companies for other IT support issues (Telstra I’m looking at you) – it is very refreshing to get such a favourable response. I’m a happy user and can still translate the odd French or Italian comments on flickr photo-streams I look at.

There is an updated version of Translation Services called KavaServices which sells for $20 and it does a whole lot of other conversion as well. I’m nothing more than a happy customer. The application is perfect for quick on the fly internet based language translation, and even translate right in the browser. Seen here are before/after shots from a flickr photo page.

Before Translation

After Translation – directly in the browser!

Thanks Kavasoft for the enjoyable support experience.

Server Migration complete

lantrix — Sun, 06 Jul 2008 12:29:58 +0000

I’ve had an on/off outage for most of the past 4 days, so to avoid hassles I put the site into maintenance mode.

I’ve actually had to decommission my 19″ server rack and the multiple servers I had for Tech Debug. There was a DNS server, kerberos, Database and web server. All the separate functions are now hosted on one OpenBSD VM that I’ve built recently. It’s running on the only remaining “non-laptop” left in my residence, which runs 24×7.

The only delay in getting back online in the last 48 hours was the MySQL data export and import. It’s a bit convoluted, and not documented in entirely one place on the MySQL documentation site (backup here, restore here), however once done once it will be easy to repeat. I still like the simplicity of PostgreSQL administration. Specifically the backup and restore:

Backup:
pg_dumpall > savefile.dump
Restore:
psql -f savefile.dump postgres

Well, there are some prep steps you should do; but it is all in one place on their documentation page.

Let me know how the site performs on the VM.

More Work?

lantrix — Wed, 25 Jun 2008 06:53:05 +0000

I’m not posting much these days since I’m currently heavily involved in a current development and build effort for a Client. (Solaris platform with Oracle 10g)

All other hours are either commuting, sleeping or playing WoW. Look forward to a number of upcoming posts on Dansguardian SQL logging, OpenBSD and of course Apple and the iPhone.

Zug Zug…. you WC3 fans will know what I mean.

Little Brother

lantrix — Tue, 13 May 2008 02:22:38 +0000

I just started reading Cory Doctorow’s Little Brother using one of his ebooks he has relesed under the Creative Commons license.
I have to admit that I had never heard of Cory of BoingBoing fame, or his books until I read about them via CelticBear.

As a ‘paranoid’ geeked I’m hooked on Little Brother, and if you like tech, geek and drama you should check it out as well.

Update: I went to buy a copy from a local bookstore, but it is not released in Australia yet. You can read the ebook or buy it from amazon.

Coral Content Distributed network

lantrix — Sun, 20 Apr 2008 11:06:28 +0000

Have you ever had your website hit on a topic that people find conflicting? When the site gets viewed by the masses, you need to be prepared. If you have access to modify your web server .htaccess file then go and have a read of the Coral CDN Overview
For those interested in the techie bits, here is my .htaccess for news site flood protection, and to allow CDN to serve up all my site images – thus offloading from my puny connection the bandwidth burden for images.
RewriteEngine On #prevent slashdot effect RewriteCond %{HTTP_USER_AGENT} !^CoralWebPrx RewriteCond %{HTTP_REFERER} blogspot\.com [NC,OR] RewriteCond %{HTTP_REFERER} reddit\.com [NC,OR] RewriteCond %{HTTP_REFERER} digg\.com [NC,OR] RewriteCond %{HTTP_REFERER} news\.slashdot\.org [NC,OR] RewriteCond %{HTTP_REFERER} slashdot\.org RewriteRule ^(.*)$ http://techdebug.com.nyud.net/$1 [R,L] #Rewrite images to allow CDN to serve them RewriteCond %{HTTP_USER_AGENT} !^CoralWebPrx RewriteRule ^(.*)/(.*\.(gif|png|jpe?g))$ http://techdebug.com.nyud.net/$1/$2 [R,L] #Wordpress rewites RewriteBase / RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /index.php [L]
mod_rewrite is your friend.

Storms and Power outages

lantrix — Thu, 03 Apr 2008 01:57:21 +0000

We’ve had some stong winds in Melbourne yesterday. Up to 130 kph!
These winds were good enough to cause a 24 hour extended power outage in my area, meaning my provider had upstream outages and the internet connection was down. Add that to the errant html comment in my last post which made the whole page commented out.
All resolved now. Now what else do I have to debug that is technical?

Free stuff

lantrix — Sat, 29 Mar 2008 05:12:10 +0000

You may have noticed that my last 3 posts were about free software.
I like free stuff. Everyone likes free stuff. Why talk about free stuff?

A friend told me that the reason he enjoys using Open Source (and usually free) apps is he can customise them. He finds it frustrating that when you pay $1K per seat for an application like Mercury (now owned by HP) that sometimes it just wont do what you need. You either work with the (often times) limited and expensive tool, or you extend the functions using your own coding and software.

You can keep up with 90kts and his Open Source load testing efforts on his blog.

Everyone likes free stuff.

Disco burning software updated

lantrix — Sat, 01 Mar 2008 15:34:41 +0000

Disco is one of the smartest looking and basic (yet powerful) CD/DVD burning solutions for your Mac. Yesterday it was updated with a maintenance release to V1.0.3, which includes quite a number of fixes for crashing that may have occurred. It has been almost 1 year since the last update so this is welcomed.

Incidentally, the developer is offering this software for USD$19.95 (and there is a very good USD->AUD exchange rate) for a limited time.
Disco has the following features:

Disc spanning – if the total size of the files you’re burning is bigger than the disc, it tries to divide them amongst multiple discs
Discography – it catalogues all the discs you have burnt for quick searching
Multi-session
And a pledge to support Blu-ray as soon as it is available on Macs

I’m not affiliated, just a happy Disco user (Thanks Mac-Heist!)