To fully understand the importance of filters and their meanings, it is necessary to understand how the network works. Here I consider the display filters that are entered in the main window of the program in the top field below the menu and icons of the main functions. (Note: 42 is the number of bytes to remove from the beginning of each frame and comprises 14 bytes for the Ethernet header + 20 bytes for the outer IP header + 8 bytes for the outer UDP header.) Well, maybe you would be better off stripping off the outer headers so you can avoid dealing with multiple UDP headers? To do this, you can use editcap, something like: editcap -T user0 -F libpcap -C 42 in.pcap out.pcap Now let's consider what happens when you apply the next filter, (udp.srcport > 48776) and (udp.srcport 48776) and (udp.port 48776) and (udp.Remember that Wireshark has display filters and capture filters. When you launch Wireshark, your packets won't be dissected correctly (yet), but you should notice an indication in the packet details pane, 'User encapsulation not handled: DLT=147, check your Preferences->Protocols->DLT_USER' (assuming of course that you don't already have a protocol assigned to this DLT). Now you need to assign DLT 147 to gtp via: Edit -> Preferences -> Protocols -> DLT_USER -> Encapsulations Table: Edit -> New -> DLT: User 0 (DLT=147) -> Payload protocol: gtp -> OK -> OK -> OKĪt this point, all the UDP filters should be easier to work with because you will only have a single UDP header now.Capture filters (like tcp port 80) are not to be confused with display filters (like tcp.port = 80). The former are much more limited and are used to reduce the size of a raw packet capture.

The latter are used to hide some packets from the packet list.Ĭapture filters are set before starting a packet capture and cannot be modified during the capture. In the main window, one can find the capture filter just above the interfaces list and in the interfaces dialog.ĭisplay filters on the other hand do not have this limitation and you can change them on the fly. Wireshark filter by ip and port range how to#.

Wireshark capture filter port