01 Firewalls course.

I will be doing a short course on firewalls on this list. Topic [FW].
The course would cover:

Theory:
An introduction to security requirements.
The TCP/IP stack and basic networking.
Packet filters
Stateless and stateful packet filters.
Application layer gateways/proxies.
Encryption, SSH, IPsec and VPNs.
Layer 8 issues.

More practical:
Iptables
The use/abuse of NAT for security.
Apache as a HTTP proxy.
Postfix w/ amavisd-new, SA and clamav for email filtering.
Backups.

Devdas Bhagat