Free proxy server software for linux

DeleGate is a multi-purpose application level gateway, or a proxy server which runs on multiple platforms (Unix, Windows, MacOS X and OS/2). DeleGate mediates communication of various protocols (HTTP, FTP, NNTP, SMTP, POP, Telnet, SOCKS, etc.), applying cache and conversion for mediated data, controlling access from clients and routing toward servers.
DeleGate translates protocols between clients and servers, applying SSL(TLS) to arbitrary protocols, merging several servers into a single server view with aliasing and filtering.
Born as a tiny proxy for Gopher in March 1994, it has steadily grown into a general purpose proxy server. Besides beeing a proxy, DeleGate can be used as a simple origin server for some protocols (HTTP, FTP and NNTP).
Main features:
- UNBOUND PROXY: A user can select target servers arbitrarily in ad hoc way showing destination in user level data specific to the protocol of the client.
- BOUND PROXY: An administrator of DeleGate can specify which destination server is used depending on accessing client.
- CACHE: A message data transferred on a protocol is cached in its inherent format and shared among DeleGate as gateway servers of different protocols.
- CONNECTION SHARING: An established connection to a server in anonymous user can be reused and shared among multiple clients.
- DATA CONVERSION: DeleGate has several built-in data conversion filters which can be applied to a specific part of data in a message on each protocol.
- PROTOCOL CONVERSION: A client of a protocol can talk with servers of other protocols via DeleGate.
- AUTHENTICATION / SECURE PROTOCOL CONVERSION: DeleGate can relay between a non-SSL client and a SSL server, or between a SSL-client and a non-SSL server.
- ACCESS CONTROL: Accesses to be permitted to pass DeleGate are described by a set of triples of destination protocol, destination server and source client.
- LOGGING: Detailed logging of DeleGate actions and protocol dependent logging in standard formats.
- AUTOMATIC INVOCATION: DeleGate can be invoked automatically on demand or at the startup time of the host system.
- RESOLVER CONTROL: You can control the combination and sequence of multiple resolution mechanisms, independently of platforms.
- ROUTING CONTROL: A route toward the server can be selected from alternatives depending on protocol, server and client (host and user).
- MOUNTING SERVERS: Multiple target servers of multiple protocols can be merged into a single server of a protocol, with resource name filtering and aliasing.
- PROXY ON DEMAND: Automatically invoked proxy just for the current session.
- ORIGIN SERVER: You can use DeleGate as simple origin servers for several protocols.
- EXTENSION BY USERS: You can attach your own graphic images, messages, and programs to DeleGate without modifiying the DeleGate program.
- TCP WRAPPER: You can use DeleGate like inetd + TCPwrapper which make your own filter program work as a server with access control.
- SCHEDULER: You can use DeleGate like crond which invokes specified commands at specified timing.
- MULTI-PLATFORM: DeleGate runs on multiple platforms and can be compiled from a common source program without any platform dependent configuration.
Whats New in 9.6.3 Alpha Development Release:
- This release fixes frozen threads or broken data which could be caused with thread based implementations of SSL and gzip filters.