At 08:39 PM 12/3/97 -0500, Adam Heath wrote: >First, a little history. > >As I am sure we all know, Linux currently does not support masquerading of video >conferencing protocols, including H.323. There are partial solutions using >IPPORTFW, but none that work transparently. > >So, a few weeks ago I started research into this project. I found that doing >this was not going to be easy. The initial connection is done on a well-known >port. During that communication, a dynamic control channel is netgotiated, and >that channel is then used to allocate 'logical' channels, for video, data, and >audio, using UDP. > >Normally, this wouldn't be a BIG problem, but the first two control channels are >encoded with ASN.1/PER. For those of you that don't know what that is, it is a >data definition language, that allows for transfer of data between disparate >machines. Also, it allows of OPTIONAL records in the data stream, which makes >it hard to just extract addresses at specific offsets. > >In my research, I had found the ASN.1 definitions for H.323, but didn't have a >compiler to convert them into C header files and translation functions. When I >went to find one, the only good one I found was SNACC, which used BER, instead >of PER.
ASN decoding, lots of fun. I once wrote one of these for an SNMP module for an embedded print server many years back. Unfortunately, I don't have access to that code anymore. I don't remember what the BER/PER stuff is, I thought it was all pretty generic. I would think you could find source for an ASN decoder in the Linux SNMP code. Might be what you are looking for. [snip] >First, I will be making a masquerading module, which will only support outgoing >connections. Then, I will implement a user-mode proxy, that will comunicate >with the kernel module, and allow incoming connections. I also want to make a >device driver to allow access to the data, audio, and video in an easier way. > Sounds great! >I plan on having a basic kernel implementation by the end of the year. > >Wish me luck+ACE- :) > Good luck. > > Adam Heath of Borg-Linux adam.heath+AEA-usa.net Join the H323 effort. Email > http://www.debian.org - Get Your Own Linux+ACE- h323-request+AEA-cichlid.com with > http://wwp.mirabilis.com/3375265 - Page Me the word subscribe in the body. > > Windows 95: -- 32-bit extensions and a graphical Windows v. Linux is > shell for a 16-bit patch to an 8-bit operating a no-win situation. > originally coded for a 4-bit micropro- > cessor written by a 2-bit company that It is nearly impossible to > can't stand for 1 bit of competition. look at a penguin and get angry. > >ps. The linux kernel comes with source(duh+ACE-), but I was wondering what was >thought about distributing the documentation that was used to generate the free >source. > > >- >To unsubscribe use [EMAIL PROTECTED] >Archives http://www.scruz.net/~cichlid/h.323-archive > Al Youngwerth [EMAIL PROTECTED] -- TO UNSUBSCRIBE FROM THIS MAILING LIST: e-mail the word "unsubscribe" to [EMAIL PROTECTED] . Trouble? e-mail to [EMAIL PROTECTED] .
