17.5. Custom tls logging

In your Suricata.yaml, find the tls-log section and edit as follows:

- tls-log:
    enabled: yes      # Log TLS connections.
    filename: tls.log # File to store TLS logs.
    append: yes
    custom: yes       # enabled the custom logging format (defined by customformat)
    customformat: "%{%D-%H:%M:%S}t.%z %a:%p -> %A:%P %v %n %d %D"

And in your tls.log file you would get the following, for example:

12/03/16-19:20:14.85859 -> VERSION='TLS 1.2' suricata.io NOTBEFORE='2016-10-27T20:36:00' NOTAFTER='2017-01-25T20:36:00'

The list of supported format strings is the following:

  • %n - client SNI

  • %v - TLS/SSL version

  • %d - certificate date not before

  • %D - certificate date not after

  • %f - certificate fingerprint SHA1

  • %s - certificate subject

  • %i - certificate issuer dn

  • %E - extended format

  • %{strftime_format}t - timestamp of the TLS transaction in the selected strftime format. ie: 08/28/12-22:14:30

  • %z - precision time in useconds. ie: 693856

  • %a - client IP address

  • %p - client port number

  • %A - server IP address

  • %P - server port number

Any non printable character will be represented by its byte value in hexadecimal format (|XX|, where XX is the hex code)