uredir —
UDP port redirector
uredir |
[ -hinsv
]
[-I
ID
]
[-l
LVL
]
[-t
SEC
]
[[SRC]:PORT ]
[DST]:PORT |
uredir is a small tool to redirect UDP
traffic. It can be used as a poor man's filtering tool, e.g. for small
multihomed embedded systems without a built-in firewall.
uredir forwards packets to a specified
destination remembering the sender's address, any packets received from the
destination are in turn forwarded to the sender.
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, useful in
particular on embedded systems.
For a TCP port redirector, try
redir(1), which now
has the same maintainer as
uredir(1).
-h- Print a summary of the options and exit
-i- Run in inetd mode, read data from stdin. Implies
-n, always runs in foreground
-I
ID- Identity, tag syslog messages with the ID name, default: process name
-l
LVL- Set log level: none, err, info, notice (default), debug
-n- Run in foreground, do not detach from controlling terminal
-s- Use syslog, even if running in foreground, default w/o
-n
-t
SEC- Set timeout to SEC seconds for connections, default 3
-v- Show program version
- [SRC]:PORT
- Source, or outer/public, IP and UDP port to bind to, the SRC can be left
out to default 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 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
To run
uredir in inetd mode, e.g. to redirect
SNMP requests, and timeout after 5 sec, try the following. 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
Syntax may vary between different inetd implementations and UNIX distributions.
redir(1)
inetd(8)
Use the project's GitHub page to file bug reports, feature requests or patches
-- preferably as pull requests
⟨https://github.com/troglobit/uredir⟩
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.