How to write a filter in Wireshark/Ethereal that displays only packets with a specific string?

Question

Wireshark supports filters like this:

ip.addr == 192.168.0.1

What is the syntax to check the packet content?

(C# equivalent of what I want)

content.Contains("whateverYouWant")

Answer 1

There seems not to be an generic way of doing this. The filter you need to apply is dependent on the protocol you are listening for. Try looking at the filter list at http://www.wireshark.org/docs/dfref/.

Answer 2

Try the "contains" or "matches" operators.

tcp contains "an aloof iguana"
http matches "my pass.+ is(?i)"

Contains does a simple case-sensitive string comparison, and is guaranteed to be in every Wireshark package. Matches lets you apply Perl-compatible regular expressions. Its availability depends on your platform. You can also use contains with byte strings:

ip contains 01:ab:9c:45