To use this on a ProxySG, either enter the command line entry as follows (take note to use quotation marks): You can also add things like DNS by adding another port: You could specify '304' or '500' by determining what the hex values for those items is. Instead of 'GET ' you could use the hex values for 'HEAD' or 'POST'. The values can be changed by replacing with the data you want. By using the filter above, you can gather only GETs with valid, new content responses. This filter is very powerful on a very busy ProxySG, as sometimes there is enough data traversing the proxy to only capture a few seconds before hitting the 100 MB limit. A typical HTTP response will start with 'HTTP/1.1 200 OK'. The third bullet is offset by 8 bytes and is for an HTTP response.

The second bullet restated says 'TCP offset 47455420' which is literally 'GET ' (G, E, T, space)

Most common for a transparent HTTP environment. The first part is to only capture TCP or UDP port 80. The following information is taken in part from the Wireshark Wiki page on capturing HTTP GET requests ( /CaptureFilters).

Wireshark http get filter