cat file to multicast

Question

I have a text file (test.txt) which represents captured network data. The actual protocol is text-based, with NULL line endings, so this isn't a problem.

I need to run this test captured data through my server, over a multicast port. The TTL can be zero -- I'll run both side of this on the same box.

Is there a way to essentially cat a file to a multicast port?

I already have tools that I use to do this with pcap files and other formats, but I'd prefer to use something quick and builtin rather than crack open that code to make it read text files.

This will be run on an RHEL6.2 server. Command-line, ssh session.

Solution

netcat -c -w 1 -v -u -s 127.0.0.1 239.255.0.1 30001 < test.txt

mdump was used in another session to confirm that the data was being sent:

mdump 239.255.0.1 30001 127.0.0.1

Neither netcat (nc) nor socat was installed on my RHEL6.2 system, and neither was available from the repos. So I installed netcat from source.

./configure
make
sudo make install
man netcat

Comments

[Graeme]

nc or socat?

[Graeme]

nc (possibly netcat) should be a standard tool on most systems, is this not the case on redhat?

[John Dibling]

@Graeme: man nc said no. i'll try netcat

[John Dibling]

@Graeme: Niether nc nor netcat are part of the RHEL distro, and niether were in the repos. I waws able to get netcat installed from source however.

[Graeme]

Interesting, the simple netcat package is marked as important for Debian. Seemingly there is also netcat-openbsd, which has more features than the default Debian one (which doesn't appear to be GNU either). Did you have any luck getting either to work with a multicast? Unfortunately I don't know enough about this to offer any answer other than to say these are the common tools for doing a 'cat' over a network.

[Tchakabam]

also nice btw, instead of using cat, use head/tail instead with bytes amount specified :)

[higginse]

I use this mechanism quite a bit. Great for quick testing. The downside for multicast is that the ttl (which defaults to 1 for multicast) can't easily be set, which is a bit limiting.