I have been using Linux at home for a couple years, since RedHat 7.1 and switched to ubuntu. I work as an it admin, mostly on windows servers.. But i really like Linux better and would like to get certified.

I know there is Comptia Linux+ available for cheap, I am gonna do it soon (when im done with MCSA, but i was wondering if there was other non-distro related certifications available for Linux and if any of you would recommend one over the other?

At the tip of my head, I am familiar (but dont consider myself an expert) with: squid, vsftp, openssl, cron, samba, cups, bash, ksh. i used to compile my own kernel but its been too long..

In a near future, I would like is to be able to create a Linux Domain Controller, with a mail server, antispam, firewalls, etc.. (by the way, is Iptables considered an acceptable solution for small-medium enterprise?)

thanks.