#pcap filter expr " port 80 and (tcp & 0xf0) > 2):4] = 0x47455420 or tcp & 0xf0) > 2)+8:4] = 0x20323030)"Īlternatively, in the UI go to Maintenance > Service Information > Packet Captures and enter just the filter you want into the filter section (quotation marks are not needed). To use this on a ProxySG, either enter the command line entry as follows (take note to use quotation marks): (port 80 and (tcp & 0xf0) > 2):4] = 0x47455420 or tcp & 0xf0) > 2)+8:4] = 0x20323030)) or port 53 Apply the following filter expression to reduce the list to the http packets with the URL path prefix /api and method POST, for example. Here is an example: So you can see that all the packets with source IP as 192.168.0.103 were displayed in the output. I use Wireshark to capture a HTTP video stream and Ive use the following filter to filter out the relevant GET requests. You can also add things like DNS by adding another port: For example, to display only those packets that contain source IP as 192.168.0.103, just write ip.src192.168.0.103 in the filter box. 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. there are 'TCP acknowledge' packets received by PC in capture file, but packets sent by PC, which are acknowledged by them, aren't shown. What is missing: There is not a single outgoing packet, despite they are obviously on the net. The first part is to only capture TCP or UDP port 80. Capture sample looks like it's filtered, since it contains only packets sent to your PC IP address. The following information is taken in part from the Wireshark Wiki page on capturing HTTP GET requests ( /CaptureFilters). A comprehensive reference of filter fields can be found within Wireshark and in the display filter reference at FILTER SYNTAX Check whether a field or protocol exists The simplest filter allows you to check for the existence of a protocol or field.
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