Hi,

I have been told that some unwanted messages are being sent by my computer through port 53 which I need to stop.

Could anyone tell me how can I block this port for outward traffic? If it helps, I am using fedora 10.

Thanks in anticipation.

port 53 is dns. don't block it, that would be very daft.

I also realized the same thing as I googled the function of port 53. But then do you have any idea what might have been going wrong? How, if at all, is it possible for me to keep the port open but prevent unknown applications or services from making traffic at that port?

Thanks

I can't really comment without knowing what these messages are, who is telling you to address these issues etc...

One thing actually is that dns is *normally* UDP but can also run over TCP, and you could block TCP/53 if whatever it is is doing that.

I have been asked to do that by the local network administrator. He says that my PC is sending some anomalous messages through this port to a certain IP address on the network.

Does that make some sense?

And suppose I have to block TCP/53. Could you tell me how it is done?

Thanks

I would try to find out what is doing this and stop it.

Do you have, for example, mdns/avahi running? I think they use the multicast DNS protocol on port 53. I'd only try blocking port 53 if you run out of other ways to work out what is going on and you think that blocking port port 53 will break something and you'll get an error message to tell you what it was.

You could also try netstat to see if you have anything grabbing hold of port 53. Or, wireshark, to see if you can see what is sending out packets; if the network is anything like busy, you'll probably have to do a bit of filtering to just capture the data that you want.