live monitoring TCP sessions

["sami seclist" <sg.seclists () gmail com>]

Hi list,

I need to size a firewall for one of our customers, I especially need
to find the average number of sessions per user for that particular
company.

So, what are tools that can be used to monitor TCP sessions on the
network, and that could generate values I need, or that could be
easily customized for that purpose.

Thanks.