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 10.10.10.4:58274 -> 192.0.78.24:443 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)