Allow netcat to be a tun tunnel broker
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Authored by thj on Nov 18 2022, 4:16 PM.

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Klara
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Commits

rGfe701c39e8aa: if_tun: Add basic connectivity test with nc tun support
rGcef7ab70ff44: netcat: Allow nc to be an if_tun tunnel broker

Summary

Add tests with this new functionality to test that tun devices can pass packets.

You need to figure both sides with netcat, one side should listen:

ifconfig tun create

tun0

nc -u -l --tun /dev/tun0 192.168.100.12 2600 &
ifconfig tun0 inet 10.4.100.2/24 10.4.100.3 up

ifconfig tun create

tun0

nc -u --tun /dev/tun0 192.168.100.12 2600 &
ifconfig tun0 inet 10.4.100.2/24 10.4.100.2 up

This is very naiive and probably quite fragile, but it is enough to enable tun
tests using just netcat.

Add usage and help strings

Add tun tunnelling test using nc

Diff Detail

Repository

rG FreeBSD src repository

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Lint Warnings

Severity	Location	Code	Message
Warning	tests/sys/net/if_tun_test.sh:	CHMOD1	Invalid Executable

Unit

No Test Coverage

Build Status

Buildable 49072
Build 45961: arc lint + arc unit

Event Timeline

thj created this revision.Nov 18 2022, 4:16 PM

Herald added subscribers: glebius, melifaro, ae, imp. · View Herald TranscriptNov 18 2022, 4:16 PM

thj requested review of this revision.Nov 18 2022, 4:16 PM

Harbormaster completed remote builds in B48420: Diff 113272.Nov 18 2022, 4:16 PM

thj retitled this revision from Allow netcat to be a tun tunnel broker Add tests with this new functionality to test that tun devices can pass packets. to Allow netcat to be a tun tunnel broker.Nov 18 2022, 4:35 PM

thj edited the summary of this revision. (Show Details)

thj mentioned this in D37437: if_tun: Enable tun devices to be used with netmap.Nov 18 2022, 4:37 PM

Just some minor simplifications, I think we can just use tun_fd being a valid fd as an indicator that we should be tunneling instead of tracking that in separate state.

contrib/netcat/netcat.c
149	Normally we just use `CHAR_MAX` to make it clear
163	IMO, let's init `tundev` to `NULL` here
336	`tundev` could be a `const char *` and you can avoid having to make a copy of `optarg` here, since we don't need to mutate it later.
338	Drop `FreeBSD_tun` completely, the below conditional can use `tundev != NULL`
583	`tun_fd >= 0`, since we initialize it to -1
861	Let's use `tun_fd >= 0` for these ones, as well