Presentation slides

HTTP Proxies - Explicit and Transparent

• Proxies are intermediaries which, possibly after modifying the HTTP request, forward it to its destination. Explicit proxies are specifically identified in user agents (UA). Transparent proxies (a.k.a. HTTP interceptors) intercept HTTP requests underway without UAs knowledge. 
• These slides outline the various services of these two kinds of proxies; show the differences on TCP level, and illustratiate both approaches with Squid software.

Proxies from User Agents' perspective

• Hide LAN network structure from the outside world, optimize the HTTP communication (cache responses, compress, convert media types), filter inappropriate content.
• In two parallel columns - compare both approaches

How the TCP/IP is handled on a low level

Examples of Explicit/Transparent Proxy Setups

• Things to try out
  *a. Configure your own squid, proxy configuration scripts, Switchproxy plugin
  *a. HTTP intercept, routing tables, wireshark, tcpdump