Asterisk WebRTC DTLS-SRTP issue

Asterisk Asterisk Support
1

Hi, I am looking for a little bit of help from the community if possible please? I’m experimenting with Chrome (JSSIP), WebRTC and Asterisk 13.2.0-rc1. I currently have everything configured as per the latest recommendations and so far have made some promising progress.

I have two peers defined in Asterisk, which I am able to successfully register with. Signalling seems to be working nicely, as I am able to initiate and reject calls without any problems.

However, when I answer a call which is initiated, it terminates immediately. In the Asterisk logs, I see the following:-

[2015-05-12 13:03:33] WARNING[3931][C-00000009] res_rtp_asterisk.c: Could not set policies when setting up DTLS-SRTP on ‘0x7f752c001320’
[2015-05-12 13:03:33] WARNING[3931][C-00000009] res_rtp_asterisk.c: RTP Read error: Unspecified. Hanging up.

I have generated keys/certificates for Asterisk and they are declared in sip.conf (example):-

[XXX]
type=friend
username=XXX
host=dynamic
secret=XXXXXXXXXX
encryption=yes
avpf=yes
icesupport=yes
context=default
directmedia=no
transport=ws,wss,udp
force_avp=yes
dtlsenable=yes
dtlsverify=fingerprint
dtlscertfile=/etc/asterisk/keys/asterisk.pem
dtlsprivatekey=/etc/asterisk/keys/asterisk.pem
idtlscafile=/etc/asterisk/keys/ca.crt
dtlssetup=actpass
dtlsrekey=60
videosupport=no
nat=no
disallow=all
allow=ulaw

Please could anyone shed some light on what I’m doing wrong? Thank you :smile:

2

For anyone else experiencing this issue, it turned out that it was down to compiling Asterisk on a 64-bit system and srtp not being compiled correctly.

3

Can you specify the steps to compile the srtplib in a 64 bits system?

I did it in the following way:

wget http://srtp.sourceforge.net/srtp-1.4.2.tgz tar zxvf srtp-1.4.2.tgz cd srtp autoconf ./configure --enable-pic --libdir=/usr/lib64 make && make install

I’m having the same error :

[Jun 2 12:02:21] WARNING[41930][C-00000000]: res_rtp_asterisk.c:1974 dtls_srtp_setup: Could not set policies when setting up DTLS-SRTP on '0x7fe818008c40' [Jun 2 12:02:21] WARNING[41930][C-00000000]: res_rtp_asterisk.c:4249 ast_rtp_read: RTP Read error: Unspecified. Hanging up.

Handshake seems to happen with the client that receives the call but after that asterisk sen BYE


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4

as an aside, people reading this should be getting libsrtp from github [1] now, as that’s where Cisco moved the repository. It’s received important bug-fixes since its sourceforge days that, if ignored, will lead to problems - there are a few on the Asterisk issue tracker that turned out to be libsrtp problems.

[1] - github.com/cisco/libsrtp