FRIENDS,


Q.)How to change the default PORT NUMBER OF DNS IN LINUX ?

DNS port 53 is what virtually all applications use to query DNS so changing it would be pointless as it would only insure most applications could no longer query your DNS server.

Why are you asking this question? Maybe there's another way to accomplish your underlying purpose?

Thanks Friend for replying to my question.

Regards,
Aparna.

I'm not sure that I know enough to answer all of the questions that this might really be, but I do know enough to know that it is ambiguous enough to be difficult to answer:

• the default number (53) is the default, because it is what happens if you don't change it. If, eg, post install, you change it, you are no longer using the default. From that point of view, you can't change the default, unless you make, a new distro with a different default; otherwise, you have actually changed the port-in-use, but not changed the default. I don't think that this is what you wanted to know
• Probably you wanted to know 'how do you change the number from the default?'. there are several ways to do that, and it, kind of, depends on exactly what you are trying to do -
• are you trying to get a client to use an unconventional port?
• are you trying to get a DNS server to respond on an unconventional port?

In any case, you can probably get iptables to move traffic from one port to another. That is less than an enthusiastic recommendation that this is what you ought to do in some particular circumstance, though.

If you are talking about the DNS server (eg, Bind, or whatever) there may well be a configuration file option to change one of the ports - potentially, there is a 'listen-on' port and 'forward-query-on' port to consider, and you should know which of those you are talking about. But then, I certainly can't say that I know all DNS Servers well enough to suggest that they are all as flexible as BIND...but, then again, you can also argue that this is, as a general consideration, a good thing.