[asterisk-bugs] [Asterisk 0015182]: [patch] T.38 invite does not always comply with RFC 2327

[Asterisk Bug Tracker]

The following issue is now READY FOR TESTING. 
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https://issues.asterisk.org/view.php?id=15182 
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Reported By:                CGMChris
Assigned To:                
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Project:                    Asterisk
Issue ID:                   15182
Category:                   Channels/chan_sip/T.38
Reproducibility:            sometimes
Severity:                   minor
Priority:                   normal
Status:                     ready for testing
Target Version:             1.4.27
Asterisk Version:           1.4.25 
Regression:                 No 
SVN Branch (only for SVN checkouts, not tarball releases): N/A 
SVN Revision (number only!):  
Request Review:              
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Date Submitted:             2009-05-22 09:31 CDT
Last Modified:              2009-06-12 13:47 CDT
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Summary:                    [patch] T.38 invite does not always comply with RFC
2327
Description: 
See http://www.faqs.org/rfcs/rfc2327.html, section 6:

"Note: For transports based on UDP, the value should be in the range 1024
to 65535 inclusive.  For RTP compliance it should be an even number."

My SIP provider drops the call when my signaling specifies an odd numbered
media port for T.38 (per RFC 2327).

In most of my tests, the media port in the T.38 invite is even:
1. From my provider to Asterisk
2. From Asterisk to my ATA
3. From my ATA back to Asterisk

At this point, (step 4) Asterisk seems to be prone to generating an odd
numbered port for signaling to my provider.

I *think* this issue has not been noticed widespread because ALG on most
routers corrects this behavior.  I do NOT have a problem using T.38 with a
cheap $60 Linksys router, however, using an off-brand router from Hong Kong
with no ALG support, I cannot get T.38 to work at all.
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---------------------------------------------------------------------- 
 (0106346) mmichelson (administrator) - 2009-06-12 13:47
 https://issues.asterisk.org/view.php?id=15182#c106346 
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I've uploaded a patch for testing. If you apply this patch and set
use_even_ports = yes in udptl.conf, Asterisk should only designate
even-numbered ports for T.38 offers. Let me know if it works out for you. 

Issue History 
Date Modified    Username       Field                    Change               
====================================================================== 
2009-06-12 13:47 mmichelson     Note Added: 0106346                          
2009-06-12 13:47 mmichelson     Status                   new => ready for
testing
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