Close port 53 Solaris8

Posted on 2006-05-28
Last Modified: 2013-12-27
53/tcp    open  domain

How to close port 53 in solaris 8?...i still can telnet into it. Tq
Question by:emlily
    LVL 10

    Expert Comment

    Seeing port 53/tcp open on your system means that DNS is running as a service.

    The easiset way is to stop DNS.  Do you need DNS running as a server on your box ?

    Author Comment

    i didnt run the dns in my box....if i remove the dns, will it disturb my internet connection? let say i still using the /etc/resolv.conf? how to remove the 53 port and close it?
    LVL 10

    Accepted Solution

    Whether it distrubes your internet connection depends on how your /etc/resolv.conf file is setup.

    To see if your DNS *client* configuration is influenced by you running a DNS server on your server, just look at your /etc/resolv.conf file.  Is the /etc/resolv.conf file contains nothing, or "", or one of the physically configured IP addresses on your system, then your DNS *server* is probably either a caching-only DNS server or a full fledged authoritative server (but I doubt it from your comments).  To remove the this dependency from your DNS client configuration, you need to modify your resolv.conf to point to an external DNS server that you're allowed to use.

    The DNS server is started in /etc/rc2.d/S72named on Solaris 9 and below ( are you running Solaris 10 or something lower ? )  If you running Solaris 9 or below, simply do:

    cd /etc/rc2.d
    sh S72named stop
    mv S72named disable.S72named
    (or maybe something like "mv S72named s72named")

    The important thing is to make sure the capital S in frost of the file name no longer shows up in front.

    BTW, the 53/tcp is specifically used by DNS servers for what's known as a zone transfer.  This is used by backup DNS servers.  Basically your make updates to the primary DNS server and it lets the backup DNS servers know that a modification was made to the DNS tables.  Port 53/tcp is used to transfer the zone information to the secondary DNS servers.  Its only used by DNS servers.  Client only used 53/udp when talking to DNS servers.

    Author Comment

    im using solaris 8...thanks for the info...going to test it now. tq

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