[CentOS] Default Firewall Entries

Mon Apr 11 10:22:49 UTC 2005
Johnny Hughes <mailing-lists at hughesjr.com>

On Sun, 2005-04-10 at 20:24 -0700, Mickael Maddison wrote:
> I'm curious... there seems to be a couple of default firewall rules
> that I'm not familiar with in the CentOS 4.0

These are also present in RHEL-4 and FC-3 from RedHat :)

> Particularly, the 5353 udp allowing from and the 631 udp.
> Anyone know what these are for, and if they should be disabled?

The 5353 udp is multicast DNS (or mDNS for short) ... here are a couple

The 631 udp port is for "Internet Printing Protocol".  It is how cupsd
sees external printers. Here are some details:
Also ... specifically from the RHEL-4 release notes:


The firewall constructed by the system-config-securitylevel
configuration tool now allows CUPS and Multicast DNS (mDNS) browsing.
Note that, at the present time, these services cannot be disabled by
SO ... if the box needs to do either mDNS or CUPS printer browsing, you
need them enabled.  If not, you can remove them.

Johnny Hughes

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