[asterisk-bugs] [JIRA] (ASTERISK-29128) res_srtp: Authentication failure after hold/unhold

[laszlovl (JIRA)]

    [ https://issues.asterisk.org/jira/browse/ASTERISK-29128?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=253103#comment-253103 ] 

laszlovl commented on ASTERISK-29128:
-------------------------------------

Thanks for looking into this.

The phone was actually running firmware 8.9.3.80 (I believe it's not running a newer version because all subsequent firmwares were found to contain showstopper bugs); my script to scrub sensitive information from a debug log is recognizing the firmware version as an IP address. As for libSRTP, if I understand correctly, Asterisk developers recommend to stick with 1.5.4 (https://wiki.asterisk.org/wiki/display/AST/libsrtp) instead of 2.x.

I first downgraded the phone to 8.9.3.60 and was able to reproduce the problem in exactly the same fashion. I then upgraded it back to 8.9.3.80 for the subsequent reproduction, you'll be able to find that one on Snom's servers as well.

As it concerns SRTP, a wireshark trace won't tell you much. But I created another debug log with "rtp set debug on" (as well as core debug level 1), which will show info about the sequence numbering.

> res_srtp: Authentication failure after hold/unhold
> --------------------------------------------------
>
>                 Key: ASTERISK-29128
>                 URL: https://issues.asterisk.org/jira/browse/ASTERISK-29128
>             Project: Asterisk
>          Issue Type: Bug
>      Security Level: None
>          Components: Resources/res_srtp
>    Affects Versions: 16.13.0
>            Reporter: laszlovl
>         Attachments: filtered.log
>
>
> As simple as the title indicates. Put an SRTP call on hold, unhold it, and Asterisk starts logging "SRTP unprotect failed on SSRC 1509410849 because of authentication failure" afterwards. No more audio is transmitted.
> Traced the problem to commit https://github.com/asterisk/asterisk/commit/c00b032bbfc14f40537989477229f189a1b529d7 (ASTERISK-28903), without it everything works fine.
> Asterisk 16.13, libsrtp 1.5.4.



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