Free transparent proxy software for linux

Spike Proxy is an open source HTTP proxy for finding security flaws in web sites.

SPIKE Proxy is part of the Spike Application Testing Suite and supports automated SQL injection detection, web site crawling, login form brute forcing, overflow detection, and directory traversal detection.

To Use:

python spkproxy.py [ optional port argument, 8080 is default ]
Then set up your browser to use that port for both HTTP and
HTTPS proxies.

Then watch the traffic go!

Japt-Proxy is a JAVA based Caching Proxy for Debians APT-System. Japt-Proxy is very reliable and lightning fast. Japt-Proxy is usually used in environments where several Debian systems have to be kept up-to-date without downloading the same files over and over again from the debian mirrors. Mostly these environments are data centers, Linux-powered companies, schools, public authorities and so on.
Often Japt-Proxy is used because of small sized internet connections but it is also useful to install complete debian systems over the net (read: over the proxy). Even with high volume internet connections Japt-Proxy can dramatically reduce the time to install or update Debian on many machines.
Why Java?
I know there are people out there thinking "Hey? Why Java?". There are a bunch of reasons why people asking those questions. I have a simple answer to all those questions. The answer is, that Java enabled me to easily develop the fastest and most reliable APT-Proxy. Java and the Apache Software Foundation provides such good libraries for this job, that it wasnt very hard to bring up this tool.
If you dont trust, test it - the installation takes less than five minutes!
Doesnt a general proxy server supersede an APT-Proxy?
No, it doesnt. Japt-Proxy knows the characteristics of a Debian archive and their files. It knows, for example, that .deb files wont change, because newer files would have a new name (the version is always part of the filename), hence it wont recheck if there is a newer version of this specific file.
Furthermore you can configure the Japt-Proxy to delete old versions of a package in its cache directory - a general proxy cache would simple delete files that havent been requested for some time.
So, a general caching proxy like Squid is a perfect tool for caching "normal" internet traffic. If you need a proxy for faster APT access - Japt-Proxy is the right tool for you.
Main features:
- Caching of all apt requests from Debian archives
- Multi-threaded architecture which increases the download speed enormously when several machines are requesting packages
- Builds up a partial mirror directory automatically, with exactly the same directory structure and filenames as the original mirror
- Automatic and configurable cache cleanup (purging packages in cache if newer versions exists)
- Makes sources.list configuration easier for multiple machines - if you change your internet backend server you only have to make the change once in Japt-Proxy, instead of on all Debian machines
- Works with multiple architectures
- Backend support for HTTP and FTP
- existing .debs can be copied into the Japt-Proxy cache directory (from a CD or DVD for example) and will be used by the Proxy automatically

IMAP Proxy server is a caching IMAP proxy server. It was written to compensate for webmail clients that are unable to maintain persistent connections to an IMAP server. Most webmail clients need to log in to an IMAP server for nearly every single transaction.

This behaviour can cause tragic performance problems on the IMAP server. imapproxy tries to deal with this problem by leaving server connections open for a short time after a webmail client logs out.

When the webmail client connects again, imapproxy will determine if theres a cached connection available and reuse it if possible.

How does imapproxy keep track of which server connection is for which user?

Upon the first successful login to the real IMAP server (through the proxy), imapproxy fills in a little record that contains the username, an md5 digital signature of the password and the server socket descriptor thats being used.

After you log out and then log back in again, imapproxy just has to find a record that matches your username and password. These records are stored in a hash table (with the username being the hash key) in memory, so the lookups are pretty fast.

Can IMAP Proxy support multiple backend servers?

If you want IMAP Proxy to be able to proxy to multiple backend IMAP servers, you can run multiple instances of IMAP Proxy and make sure each instance is looking at a different configuration file.

Before you do this, take a look at perdition which appears to have been designed with this specific task in mind.

Network Transparent Widgets short from NTW, is a protocol and application framework that allows a single server to serve thousands of remote GUI applications.
The client applications are nearly indistinguishable from local, native applications. The protocol is language and architecture neutral. Server language bindings for C and Java are in heavy development.
Main features:
Speed: Remote apps can run at a speed which is nearly indistinguishable from a locally running application. Since the client draws the widgets natively, its not necessary to transfer graphical data, only widget state data. This can be done asynchronously, so the responsiveness of the UI never suffers.
Persistence: Its just as easy to write the ntw protocol data to disk as it is to the network, so the state of the entire gui application can be easily saved. This also happens transparently, so the developer doesnt have to spend any time loading and saving data. Also, if a network connection dies or the client computer loses power, the application can be restarted from the point of failure at the next connection.
Portability: using the protocol, an ntw server application running on a Unix machine could talk to an ntw client for Windows, and vice versa. So a developer could write a program on Linux that could be run from any OS without any porting necessary. Any language or platform that can read and write data to a network can use the protocol to create gui apps.
Scalability: Since the ntw server does not store or draw widget graphics, the memory and computational overhead of running an ntw application is much less than a comparable X Window application. A low end machine could easily serve hundreds of remote clients.
Productivity: Users can run ntw apps without installing anything but the client. Developers can release new versions of their apps without the users having to do anything, much like a web page.
Reference Implementation:
The current reference implementation of the client implements most of the widgets in the Gtk toolkit, and is written in C using the GTK+ 2.0 toolkit for drawing the widgets and handling events. It compiles and runs on FreeBSD, Linux, and Windows, and likely other Unix variants also. Youll need the GTK+ toolkit installed to run the client, and the GTK+ development headers to compile it.
The source code also include a server reference implementation and a sample server application. The "server" is really a set of C language bindings to functions that create and send ntw widget data. The bindings can be used in much the same way as any other GUI toolkit. See the file "ntwtest.c" for the example application. Its been tested on FreeBSD, Linux, and Windows XP. The server library should compile and run on most systems with a C compiler and support for sockets, without the need for any additional libraries.
The protocol is defined by the two header files, ntw.h and ntw_signals.h. These are C header files that describe exactly the byte layout for each of the widgets and all of the opcodes and events that can be sent.
There are still some widgets missing, and some of the signals raised by GTK are not yet handled in the protocol. This will be fixed in the near future.
Note: Although the reference implementation is coded in GTK, the NTW protocol is designed to be independent of any particular widget toolkit. GTK was picked due to favorable design features and a favorable license.
Enhancements:
- 02JUL06 - Fixed bug in update.c where spin_button was switched with slider
- 02JUL06 - Removed status field from image_buffer widget protocol

HAVP (HTTP Antivirus Proxy) is a proxy with a ClamAV anti-virus scanner. HTTP Anti Virus Proxy aims are continuous, non-blocking downloads and smooth scanning of dynamic and password protected HTTP traffic.
Havp antivirus proxy has a parent and transparent proxy mode. It can be used with squid or standalone.
Main features:
- HTTP Antivirus proxy
- Scans complete incomming traffic
- Nonblocking downloads
- Smooth scanning of dynamic and password protected traffic
- Can used with squid or other proxy
- Parent proxy support
- Transparent proxy support
- Logfile
- Process change to defined user and group
- Daemon
- Use Clamav (GPL antivirus)
- Operating System: Linux
- Written in C++
- Released under GPL
Enhancements:
- Experimental support was added for chunked Transfer-Encoding, which fixes some broken sites.
- The IGNOREVIRUS configuration directive was added for whitelisting virus names.
- The CLAMBLOCKBROKEN configuration directive was added.
- Detection with AVG was improved.
- HAVP is killed if database reloading fails for Library Scanner.
- The URL is logged when a crashed scanner process is detected.
- The build system updated, adding the --prefix, --sbindir, --sysconfdir, and --localstatedir options.

POP3 Virus Scanner Proxy is a full-transparent proxy daemon which scans all mails for viruses using third party scanners (built-in support for AVPD and Trophie).

You have to set up a port redirection in the linux-netfilter (iptables) so that all connections from e.g. inside your office to any POP3 server outside in the world will not leave your router, but come a local port, on which POP3VScan listens. POP3VScan receives from the linux kernel the original destinations of packets (the POP3 server outside in the world) and will connect to them.

All data we receive from the client will be sent to the server, and vice versa. With a little enhancement: we parse the neccessary parts of the POP3 protocol and when an email is sent from the server, we store it into a file, invoke a virusscanner and send it if it is good, or we just replace it with a virus notification. It should be possible to use all scanners using the scannertype=basic. Also POP3VScan provides scannertype=avpd for high-speed scanning using Kaspersky Anti-Virus for Linux, every C programmer can easily adept other scan-daemons (trophie, sophie, antivir, ...).

Neither the client nor the server has to be configured, none of them will take notice that theres a mailscanner (except the client when he gets a virus notification or if he looks into the header, and the server gets our ip as source).

rsh.proxy project is a proxy for rsh, rexec and rlogin.

About rsh

rsh (remote shell) is a command line computer program which can execute shell commands as another user, and on another computer across a computer network. The remote system on which the rsh executes the command needs to be running the rshd daemon. The rsh command shares the same name as another common UNIX utility, the restricted shell, which first appeared in PWB/UNIX; in System V Release 4, the restricted shell is often located at /usr/lib/rsh.

About rlogin

rlogin is a Unix software utility that allows users to log in on another host via a network, communicating via TCP port 513. It was first distributed as part of the 4.2BSD release. rlogin is also the name of the application layer protocol used by the software, part of the TCP/IP protocol suite. Logged-in users can act as if they were physically present at the computer.