Asterisk SIP/TLS Transport
When using TLS the client will typically check the validity of the certificate chain. So that means you either need a certificate that is signed by one of the larger CAs, or if you use a self signed certificate you must install a copy of your CA certificate on the client.
So far this code has been tested with:
- Asterisk as client and server (TLS and TCP)
- Polycom Soundpoint IP Phones (TLS and TCP) - Polycom phones require that the host (ip or hostname) that is configured match the 'common name' in the certificate
- Minisip Softphone (TLS and TCP)
- Cisco IOS Gateways (TCP only)
- SNOM 360 (TLS only)
- Zoiper Biz Softphone (TLS and TCP)
sip.conf options
tlsenable=yes
- Enable TLS server, default isno
tlsbindaddr=<ip address>
- Specify IP address to bind TLS server to, default is0.0.0.0
tlscertfile=</path/to/certificate>
- The server's certificate file. Should include the key and certificate. This is mandatory if you're going to run a TLS server.tlscafile=</path/to/certificate>
- If the server you're connecting to uses a self signed certificate you should have their certificate installed here so the code can verify the authenticity of their certificate.tlscapath=</path/to/ca/dir>
- A directory full of CA certificates. The files must be named with the CA subject name hash value. (seeman SSL_CTX_load_verify_locations
for more info)tlsdontverifyserver=yes
- If set toyes
, don't verify the servers certificate when acting as a client. If you don't have the server's CA certificate you can set this and it will connect without requiringtlscafile
to be set. Default isno
.tlscipher=<SSL cipher string>
- A string specifying which SSL ciphers to use or not use. A list of valid SSL cipher strings can be found at http://www.openssl.org/docs/apps/ciphers.html#CIPHER_STRINGS
Sample config
Here are the relevant bits of config for setting up TLS between 2 Asterisk servers. With server_a registering to server_b
On server_a:
Code Block |
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[general] tlsenable=yes tlscertfile=/etc/asterisk/asterisk.pem tlscafile=/etc/ssl/ca.pem ; This is the CA file used to generate both certificates register => tls://100:test@192.168.0.100:5061 [101] type=friend context=internal host=192.168.0.100 ; The host should be either IP or hostname and should ; match the 'common name' field in the servers certificate secret=test dtmfmode=rfc2833 disallow=all allow=ulaw transport=tls port=5061 |
On server_b:
Code Block |
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[general] tlsenable=yes tlscertfile=/etc/asterisk/asterisk.pem [100] type=friend context=internal host=dynamic secret=test dtmfmode=rfc2833 disallow=all allow=ulaw ;You can specify transport= and port=5061 for TLS, but its not necessary in ;the server configuration, any type of SIP transport will work ;transport=tls ;port=5061 |