tcpdump -w command doesn't write to file

andykerouac · 03-02-2004, 05:13 PM

Anyone know why when I run < tcpdump -w file > I get know output in the file specified. I get network traffic on standard output but nothing when I try to redirect to a file.

itsjustme · 03-02-2004, 05:54 PM

I don't know why, but, from man tcpdump:

"In all cases, only packets that match expression will be processed by tcpdump."

With expression being the last thing on the command line, or so it seems.

andrewlkho · 03-03-2004, 07:10 AM

If you check the man pages, this writes the *raw* package to file, hence if you view the file, you'll get a load of binary. The quickest / easiest way to write to a file is:
# tcpdump > filename