Talk:Linux System Administration class
we might take a look at these links for the iptables discussion:
re ssh tunnelling - https://wiki.archlinux.org/index.php/Secure_Shell#Forwarding_other_ports
... don't know if this is as good as Daniel's, but there is also LLTHW's Exercise 27 and its Extra Credit links through http://nixsrv.com/llthw/ex27 . YMMV though.
random tangent (cf windows more than linux) - interesting bootkit info: http://go.eset.com/us/resources/white-papers/The_Evolution_of_TDL.pdf
There is a good addendum to Jim's net_config writeup that better explains why 10.x.x.x and 192.168.x.x networks are often used internally. It's entitled 'RFC 1597 - Address Allocation for Private Internets (RFC1597)' and its webpage is http://www.faqs.org/rfcs/rfc1597.html.
The most interesting section here is the one starting with
The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks of the IP address space for private networks:
10.0.0.0 - 10.255.255.255 172.16.0.0 - 172.31.255.255 192.168.0.0 - 192.168.255.255