Squid Proxy Cache Server

Squid is a full-featured web proxy cache server that caches and forwards HTTP, HTTPS, FTP, and gopher internet requests, reducing bandwidth and improving response times by caching frequently-requested web pages. Developed since 1996 (originally by Duane Wessels at UC San Diego as Harvest Cache), Squid is one of the oldest and most widely deployed proxy servers. Key features include: HTTP and HTTPS proxy (forward proxy for caching HTTP and HTTPS web requests with CONNECT method tunneling for encrypted traffic), reverse proxy (acceleration mode serving cached content to clients on behalf of origin servers), caching hierarchy (hierarchical caching with parent, sibling, and child proxy relationships enabling distributed cache architectures), ICP and HTCP (Inter-Cache Protocol for cache-to-cache communication in hierarchical deployments), access control (extensive ACL system for filtering by source IP, destination domain, URL pattern, time of day, user authentication, and protocol type), authentication (Basic, Digest, NTLM, Negotiate with LDAP, PAM, RADIUS, and database backends), URL rewriting (redirector programs for URL transformation and content filtering), delay pools (bandwidth throttling and rate limiting per user or IP with configurable bucket sizes and restore rates), SSL interception (SSL bump for inspecting HTTPS traffic with dynamic certificate generation), log analysis (access log format compatible with Webalizer, AWStats, and custom analysis), and scalability (thousands of concurrent connections with configurable cache memory and disk cache).