Monitor/log UDP traffic?

[Kevin]

Hey guys. This may not be the best place to post (my question isn't
really Java-specific) but maybe you can help.

I'm doing research on a simulated soccer system called Robocup. Robocup
clients communicate with a server via UDP, and there is an established
protocol for comms sent back and forth between a client and server.

Right now all I want to do is monitor, and log to a file, all the
communications that happens between a client and the server. For simplicity
let's say that all I want to do is log everything that the server sends
to one of its clients.

Someone else in my lab has written a program that acts as a forwarding-
proxy... you connect the client to this program, and this program forwards
everything from the client to the real server, and from the real server
back to the client. (written in Java)

The program worked for the Robocup clients/servers that were in use at
the time he wrote it (2 years ago) but now, for some reason, it no longer
seems to work properly. (New server protocol? The docs don't seem to
indicate any changes have occurred...)

I've spent too long on this already...

Before I really get into debugging his tool, I wanted to ask if there
are other, existing tools that I could use to do what I want. Otherwise
I'm going to try to debug his tool, or write my own in Java.

 

[Kevin]

Hey guys. This may not be the best place to post (my question isn't
really Java-specific) but maybe you can help.

Having done some more reading in this group....

Will tcpdump and ethereal do what I need? I don't particularly care about
packet headers, I just want to know what was the ASCII data that was sent
from the server to a particular client (and vice versa).

I also ideally would like to be able to isolate the data coming to/from
one particular client.. the server can be talking with up to 22 of these
clients, all running on one or two machines.

Thanks..

 

[Steve Horsley]

Having done some more reading in this group....

Will tcpdump and ethereal do what I need? I don't particularly care about
packet headers, I just want to know what was the ASCII data that was sent
from the server to a particular client (and vice versa).

I think Ethereal will do the trick for you. I've never used tcpdump. You
might even discover why the proxy doesn't work any more. Ethereal also
has capture and display filters that will let you pick out specific
conversations.

Steve

 

[Nigel Wade]

Having done some more reading in this group....

Will tcpdump and ethereal do what I need? I don't particularly care about
packet headers, I just want to know what was the ASCII data that was sent
from the server to a particular client (and vice versa).

I also ideally would like to be able to isolate the data coming to/from
one particular client.. the server can be talking with up to 22 of these
clients, all running on one or two machines.

Thanks..

Both tcpdump and ethereal can do what you want.

Tcpdump is the simpler of the two in its requirements for installation but
is less capable than ethereal. For simple packet capture and display it gets
the job done.

Ethereal is a more full blown packet analyser. It's much easier to view
specific parts of individual packets without getting overwhelmed by output.
But it does require more supporting packages/libraries.

 

[Roedy Green]

Both tcpdump and ethereal can do what you want.

for other options see http://mindprod.com/jgloss/sniffer.html

 

[Moonshadao]

for other options see http://www.funny-photo-photos.com/pictures/head_up_your_ass.jpg