Fitros tcpdump para conocer web visitadas

fuente: http://stackoverflow.com/questions/4777042/can-i-use-tcpdump-to-get-http-requests-response-header-and-response-body

There are tcpdump filters for HTTP GET & HTTP POST (or for both plus message body):

• Run man tcpdump | less -Ip examples to see some examples
• Here’s a tcpdump filter for HTTP GET:
  

  sudo tcpdump -s 0 -A 'tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x47455420'

• Here’s a tcpdump filter for HTTP POST:
  

  sudo tcpdump -s 0 -A 'tcp dst port 80 and (tcp[((tcp[12:1] & 0xf0) >> 2):4] = 0x504f5354)'

• Monitor HTTP traffic including request and response headers and message body (source):
  

  tcpdump -A -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'
  tcpdump -X -s 0 'tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'

For more information on the bit-twiddling in the TCP header see: String-Matching Capture Filter Generator (link to Sake Blok's explanation).