Tcpdump analysis tool

[Stephen Granger]

Hi,

I've just been asked to find out why a linux box used as a diald/internet gateway for a windows network, stays dialed up. Now I've done a tcpdump, without options, to ie tcpdump > tcpdump.dat , over a 24 hour period. I've downloaded and installed tcptrace, though it keeps telling me that the file isn't in binary format. I was wondering if anyone else used any other tools that they would recommend to carry out the analysis of a tcpdump file.
Also I wouldn't mind asking a daild guru some questions about setting time outs for the connection,  being allowed connect during a specific time range, denying connection initiations from certaion ip's, though I should really have a look at the docs and find out for myself :)

Steve