transproxy(8)

💖 transproxy — bestie's guide to the transparent proxy era 💖

okay so like, quick vibe check: this whole page is transproxy(8) from the General Use Manual, and it's about a lil program that flips on transparent proxy mode in the Linux kernel. she's a POSIX shell script, she's iconic, let's go 🫶

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✨ NAME ✨

transproxy — a program to start transproxy mode in Linux kernel. no cap, that's literally the whole job description. 💅

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🌸 SYNOPSIS 🌸

Usage: transproxy

that's it. that's the whole synopsis. she's low maintenance. ✨

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🦋 DESCRIPTION 🦋

okay so transproxy is a program that starts transparent proxy mode in the Linux kernel for use with hunt, and bestie, plot twist: the program is a POSIX shell script file. she's not even compiled. she's just a script doing main character energy things. 💜

before you even think about running her, make sure you have compiled the kernel with transproxy support. and by "make sure" I mean you have to enable the IP_FIREWALL option plus the ALWAYS_DEFRAGMENT and IP_TRANSPARENT_PROXY options when you compile the kernel. and also have iptables installed. yes, all of it. no skipping steps. 🙈

the script contains two variables that control on which port it listens and to which port the traffic will be redirected.

the default destination port is 7000 and the redirect port is 7044. to change these and other values, see below in the USAGE section for more information. (yes I'm sending you to another section, that's just how manpages work, iykyk.)

the DST_PORT is the port to which ordinary clients (source hosts) tries to connect.

the DST_PORT_PROXY is the port to which the data are redirected and on which listens the transproxy user program that does all the black magic with the data stream. 🪄✨

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👑 USAGE 👑

before using the transproxy program, edit the file script at /usr/sbin/transproxy.

you need to set some parameters, and we recommend that in Linux kernel you use the program iptables to manipulate the netfilter package filter which is supported and documented in Debian. meanwhile the programs placed by upstream ipchains and ipfwadm are no longer present in Debian since 2006. why, you ask? because ipfwadm was the package filter of Linux kernel 2.0, and ipchains was its total replacement in Linux kernel 2.2, and then iptables over netfilter came to replace ipchains completely since kernel 2.4. so ipchains and ipfwadm don't exist in the current Linux kernel versions and don't serve any purpose anymore. they're giving retired. 💀

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🎀 FILES 🎀

• /usr/sbin/transproxy

that's the one file, bestie. the whole girl. 🍓

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🌈 EXAMPLES 🌈

HOW IT WORKS TOGETHER — HUNT/TRANSPROXY/TPSERV

here is a small example how to use together hunt, transproxy and tpserv. 🫶

1. at the beginning run tpsetup/transproxy program. the default destination port is 7000 and redirecting port is 7044.
2. run tpserv/tpserv -v (or -vv).
3. run hunt and enter arp spoof daemon menu. do not start the daemon unless you modify the tpsetup/transproxy script "i" insert the single arp spoof in this order:
   • IP address (name) of your gateway or IP address (name) of destination host if the host is in the same IP subnet as source host.
   • as fake mac address enter 'my' or enter your interface MAC address.
   • enter IP address (name) of source host (client) from which you want to receive data - connections.
   • optionally enter refresh interval "t" test if the spoof was successful.
4. from the source host try to run telnet 1.1.1.1 7000 (or telnet destination_name 7000) and type some chars. the chars should be echoed back by tpserv program.

you can then play a little bit with DST_PORT setting in setup/transproxy script and/or -c option of tpserv program, or change tpserv to modify data going from/to source/destination. go off, customize your little network setup. 🔥

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💜 SEE ALSO 💜

• hunt(8)
• tpserv(8)

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⭐ AUTHOR ⭐

transproxy was written by Pavel Krauz <kra@gncz.cz>. 🫶

this manual page was written by Braulio Henrique Marques Souto <braulio@disroot.org> for the Debian project (but may be used by others). 💖

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and that's the whole page, bestie!! this gorgeous thing is transproxy-0.1, dated 05 October 2022, and it lives in section transproxy(8) of the General Use Manual. slay, periodt, go transparent-proxy your heart out 💅✨🦋