Wireshark can decode SSL/TLS sessions when the following conditions are fulfilled:
- the private key of the TLS server is known (maybe both keys are needed if mutual TLS (=client certificate) is used?).
- the TLS connections does not use a Diffie-Hellman cipher
- Wireshark captures the TLS session from the beginning (handshake)
Configure Wireshark to decode TLS:
- Copy the server's private key to the PC running Wireshark. Configure Wireshark to use the key:
- Edit → Preferences → Protocols → SSL → RSA Keys List: e.g.: ip.address.of.server,5061,sip,c:\key.pem
- If the server uses Diffie-Hellman (DH) Ciphers by default (depends on how openSSL was built) you should configure the server to use other ciphers. See
- To make sure you capture the handshake you should: 1. close the SIP client, 2. start Wireshark and start capturing, 3. start the SIP client.
If you have problems decoding the TLS session you should enable debugging in Wireshark: Edit→Preferences→Protocols→SSL→SSL Debug File