check out openisp http://www.openisp.net/
Hening Braur has also written some doc's on setting up various services in a ISP environment e.g qmail+ldap & kerberos if I remember right: http://www.bsws.de/en/technic/dns.shtml Sevan / Venture37 -- "The truth, the half-truth, and nothing like the truth." - Mark Brandon Read