Port 53...nameserver...eh?

[Serbot]

What does the nameserver port thingy contain? I'm guessing the DNS numbers...but I think I'm probably wrong http://www.linuxnewbie.org/ubb/biggrin.gif

[ndelo]

Port 53 is the port number over which your computer and its nameserver communicate. The number is actually the number of the listening port on the nameserver. You computer will contact it from a random, high-number port. It's kind of like the nameserver's ear; it's always listening for a computer to call out to it, "hey dumb ***, what is the IP of www.yahoo.com. (http://www.yahoo.com.) Basically anytime your computer tries to resolve a web address to an ip address, it contacts your DNS server, probably owned by your ISP, using this port#. The nameserver fetches the ip address of the remote site, sends it back to you, and viola! your computer knows how to contact the web page (or ftp site, email server, etc). You get the picture. Does this answer the question?

[Serbot]

ya...it does http://www.linuxnewbie.org/ubb/biggrin.gif

Have any idea why my own ISP would scan for it? http://www.linuxnewbie.org/ubb/confused.gif

[posterboy]

If you have 53 open, you are running a nameserver, much the same as your ISP. I do this, inasmuch as I have a cacheing only nameserver running. ISP's simply like to know what things the users are doing on their network. I use RoadRunner here, well, AT&T nowadays, and they scan about once a week. They often find the stuff I am running, but so far, do not complain, even though it violates the Terms of Service. They will look really hard for port 119, the usenet news port, and they certainly will complain about that, because of bandwidth. They spend a lot of time fooling around with my sendmail and messing with my Apache. All this is quite normal, and, in my experience, all ISP's I have spent some time with, do it to some degree.
Ray


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ray@raymondjones.net
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