Ethereal-users: Re: [Ethereal-users] pcap: network type 15 unknown or unsupported

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From: Guy Harris <gharris@xxxxxxxxx>
Date: Tue, 05 Jul 2005 11:05:56 -0700
diaz_d1@xxxxxx wrote:
Can yop open this file?

I can extract the capture file from the ZIP file.

Unfortunately, the capture file is probably in Nokia's stupid format, in which they modified the per-packet header to add an extra 4-byte field but DIDN'T CHANGE THE MAGIC NUMBER, so an application such as Ethereal can tell the difference between normal libpcap files and Nokia libpcap files by trying to see whether it can successfully read part or all of the file assuming it's a regular file and, if not, trying to see whether it can do so assuming it's a Nokia file. (Unfortunately, some other capture file formats *also* use the standard magic number, so the heuristics are a bit more complicated than that.)

The current heuristics for detecting Nokia files in Ethereal only check if the link-layer type value is 13, which they use for ATM; I tried adding a check for 15, but apparently the heuristics succeed for the first two packets, which is all Ethereal currently tries - perhaps it should try 3 packets, which it appears should be enough to tell the difference between the two file types.