(If your trace contains multiple ClientHello records, expand the frame that contains the first one.) What is the value of the content type? Content Type: Handshake (22)Ĥ.Does the ClientHello record advertise the cipher suites it supports? If so, in the first listed suite, what are the public-key algorithm, the symmetric-key algorithm, and the hash algorithm?Ĭipher Suite: TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA (0xc00a)ĥ.Look to the ServerHello packet.

Three fields in Record protocol are: Content type - 1 bytesģ.Expand the ClientHello record. Draw a timing diagram between client and server, with one arrow for each SSL record.Ĭlient Key Exchange, Change Cipher Spec, Encrypted Handshake MessageĬhange Cipher Spec, Encrypted Handshake MessageĢ.Each of the SSL records begins with the same three fields (with possibly different values).One of these fields is “content type” and has length of one byte. Exempting this User-Agent in Advanced -> Proxy with a wildcard (Microsoft-CryptoAPI.*) will allow requests through and should resolve the issue.1.For each of the first 8 Ethernet frames, specify the source of the frame (client or server),determine the number of SSL records that are included in the frame, and list the SSL record types that are included in the frame.

You'll notice that the User-Agent is different to your typical browser type string, so the authentication is actually being passed off to a different process. If that?s the case then you may be tempted to create a Proxy Exemption for '.crl' files which may not prove effective. HTTP/1.0 407 Proxy Authentication Required Follow the TCP Stream and you may see something like the following: Look at the pcap in Wireshark and look for a request to the CA requesting a '.crl file'Ĥ.

If nothing shows in the Web Log for this then you should get a packet capture with the user testing access to an effected site.ģ. Check to see if there is a block appearing in the Web Log, if so then you should be able to create a rule or exception to allow it through.Ģ. This will cause an error to appear which the user can most likely click through, but will of course cause some irritation.ġ. If you are experiencing issues with client machines displaying errors when trying to browse to HTTPS websites then it is possible that the client browsers are unable to download the Certificate Revocation List (crl) from the certificate authority.

Back to Knowledgebase How can support troubleshoot certificate revocation errors?Īll Barracuda Web Filters, All Firmware Versions.

Wireshark certificate capture