Two basic security questions

[Thomas Boulay]

Hi all,
        I just recently installed YDL 3.0.1 and in the interests of
making it secure I have two questions:

1.  I can't seem to upgrade yum because it requires libxml2-python.  I
tried to install libxml2-python with yum but it said I needed libxml2.
The only thing is, I'm pretty sure that libxml2 is installed, version
2.5.4.  The libxml2-python seems to be looking for libxml2 v2.5.2.  Any
thoughts?  Anyone have the 2.5.2 so that I could remove 2.5.4?

2.  I'm having trouble figuring out how to limit servies and play nice
with the firewall.  Everytime I modify the firewall and reboot, any
changes I've made aren't saved.  What I'm looking for this machine to do
is to allow ssh and sftp connections, and allow http, smtp and pop3
programs to do their thing and block everything else.  Anyone care to walk
me through that?

Thanks in advance,
Tom