If you know the real linktype (e.g., Ethernet = 1), you can patch the file:
printf '\x01\x00' | dd of=capture.pcap bs=1 seek=20 count=2 conv=notrunc
Warning: Only do this if you are certain the packet data matches the new linktype; otherwise, dissection will be invalid. -pcap network type 276 unknown or unsupported-
Use editcap (part of Wireshark) to rewrite the file with standard Ethernet headers: If you know the real linktype (e
editcap --dlt 1 broken.pcap fixed.pcap
This forces DLT type 276 to be reinterpreted as type 1. Caution: Works only if the mpacket inside contains standard Ethernet frames. If your tool strictly enforces lengths, it may still fail. Warning: Only do this if you are certain
When writing code that reads pcap files, always: