p0f -i eth1 -A 'port 80'
p0f - passive os fingerprinting utility, version 2.0.8
(C) M. Zalewski <lcamtuf@dione.cc>, W. Stearns <wstearns@pobox.com>
p0f: listening (SYN+ACK) on 'eth1', 61 sigs (1 generic, cksum B253FA88), rule: 'port 80'.
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41072 (link: ethernet/modem)
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41073 (link: ethernet/modem)
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41075 (link: ethernet/modem)
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41074 (link: ethernet/modem)
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41076 (link: ethernet/modem)
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41077 (link: ethernet/modem)
86.59.118.148:80 - UNKNOWN [5792:57:1:60:M1460,S,T,N,W7:ZAT:?:?] (up: 1109 hrs)
  -> 192.168.1.13:41078 (link: ethernet/modem)