UREDIR(1)

💖 UREDIR — the UDP port redirector, bestie edition 💖

okay so this is uredir(1), a lil general commands manual page, and it is literally the most unhinged-useful tiny tool. it redirects UDP traffic. that's it. that's the whole vibe. 🦋

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✨ NAME ✨

uredir — UDP port redirector. no cap, that's the whole job description. 💅

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🌸 SYNOPSIS 🌸

uredir [-hinsv] [-I ID] [-l LVL] [-t SEC] [[SRC]:PORT] [DST]:PORT

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🎀 DESCRIPTION 🎀

so uredir is a small tool to redirect UDP traffic. it can be used as a poor man's filtering tool — like, e.g. for small multihomed embedded systems that don't have a built-in firewall. it's giving resourceful. it's giving making it work with what you've got. 👑

uredir forwards packets to a specified destination, and it remembers the sender's address while doing it. any packets received from the destination get forwarded right back to the sender. it's a whole two-way situationship, but like, a functional one. 💞

when uredir is launched from inetd(8) it does not immediately exit when the first reply has been forwarded. instead it lingers for three (3) seconds in case more requests are received — e.g. in the case of an SNMP walk. this helps conserve precious system resources, which is especially useful on embedded systems. the way it just... waits politely? iconic. 🌈

if you want a TCP port redirector instead, try redir(1) — which now has the same maintainer as uredir(1). family reunion, fr fr. 🫶

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💅 OPTIONS 💅

• -h — print a summary of the options and exit. the classic "help me bestie" move.
• -i — run in inetd mode, read data from stdin. implies -n, and always runs in foreground. no detaching, no hiding. main character behavior only.
• -I ID — identity! tag syslog messages with the ID name. default: the process name.
• -l LVL — set the log level. your choices are: none, err, info, notice (default), debug.
• -n — run in foreground, do not detach from the controlling terminal. clingy in the best way.
• -s — use syslog, even if running in foreground. this is the default when you don't pass -n.
• -t SEC — set the timeout to SEC seconds for connections. default is 3.
• -v — show program version. quick lil flex. ✨
• [SRC]:PORT — source, or outer/public, IP and UDP port to bind to. the SRC can be left out, and then it defaults to 0.0.0.0. must not be set when running in inet mode, -i.
• [DST]:PORT — destination, or inner/private, IP and UDP port to redirect to. this is where the packets are going, bestie.

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🌟 EXAMPLE 🌟

this simple UDP proxy example forwards inbound DNS requests on any interface to an external DNS server on 192.168.0.1:

uredir :53 192.168.0.1:53

see how the SRC got left out? that's the 0.0.0.0 default doing its thing. 🍓

to run uredir in inetd mode — e.g. to redirect SNMP requests — and timeout after 5 sec, try the following. it runs in foreground, as required for inetd services, and uses syslog for logging:

snmp dgram udp wait root uredir -it 5 127.0.0.1:16161

heads up bestie: syntax may vary between different inetd implementations and UNIX distributions. 👀

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🔥 SEE ALSO 🔥

redir(1) inetd(8)

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💀 BUGS 💀

use the project's GitHub page to file bug reports, feature requests or patches — preferably as pull requests ⟨https://github.com/troglobit/uredir⟩

like, they really do want the pull requests. don't be shy. 🧚

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👑 AUTHORS 👑

uredir used to be based on udp_redirect by Ivan Tikhonov, but is today based on youdp by Tobias Waldekranz. current maintainer is Joachim Nilsson. glow-up complete. ✨

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and that's the whole page, bestie! this one came from the Debian crowd and it's dated 17 April, 2016 — so it's an elder but it still ate. mwah, bye! 💖🎀🦋