Capture some packets and save it as USNF format.Download and install the latest Ruby Windows One Click Installer.Download Unsniff Network Analyzer (its a free download).The complete script ( xcert.rb) is available at the Unsniff Scripting Samples pages on our new Wiki. So we can just select the PDUs which contains “Server Certificate” anywhere in its description. Luckily for us, Unsniff sets the Description field of each PDU to contain the names of handshake messages. So we need to work with PDU’s for this example.

TLS is a message layer built on top of a bytestream layer TCP. What you see in the PDU sheet are reassembled messages without regard for packet boundaries. Unsniff monitors PDUs as top level units. Typically the final packet in the stream contains a link to reassembled content. In Wireshark the unit of analysis is the link layer packet, i.e Ethernet or Wireless frames. We want to pull out commonName/orgName for each subject+issuer pair Key methods in the script How to pull out all reassembled SSL/TLS PDU records which contain a Server Certificate?Ī quick note : Users of Wireshark maybe a bit confused here.

For each cert in chain navigate and print the commonName and organizationName of the subject and issuer.

Pull out all the PDUs containing a Server Certificate.

We will write a tiny Ruby script and the Unsniff Scripting API to accomplish this task. Until the chain ends ( ideally in a root CA )

Analyzing https wireshark