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authorStefano Brivio <sbrivio@redhat.com>2023-11-21 17:18:26 +0100
committerStefano Brivio <sbrivio@redhat.com>2023-11-22 07:19:36 +0100
commit4117bd94f967709074ff1f310d7334ab1876ddae (patch)
treeea5c55cfa511a40df6b1b2a6deeaa14cb98820ee /tap.c
parent4f1709db1b61c14729a6313d860323ec65772a37 (diff)
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port_fwd, util: Don't bind UDP ports with opposite-side bound TCP ports
When pasta periodically scans bound ports and binds them on the other side in order to forward traffic, we bind UDP ports for corresponding TCP port numbers, too, to support protocols and applications such as iperf3 which use UDP port numbers matching the ones used by the TCP data connection. If we scan UDP ports in order to bind UDP ports, we skip detection of the UDP ports we already bound ourselves, to avoid looping back our own ports. Same with scanning and binding TCP ports. But if we scan for TCP ports in order to bind UDP ports, we need to skip bound TCP ports too, otherwise, as David pointed out: - we find a bound TCP port on side A, and bind the corresponding TCP and UDP ports on side B - at the next periodic scan, we find that UDP port bound on side B, and we bind the corresponding UDP port on side A - at this point, we unbind that UDP port on side B: we would otherwise loop back our own port. To fix this, we need to avoid binding UDP ports that we already bound, on the other side, as a consequence of finding a corresponding bound TCP port. Reproducing this issue is straightforward: ./pasta -- iperf3 -s # Wait one second, then from another terminal: iperf3 -c ::1 -u Reported-by: Akihiro Suda <akihiro.suda.cz@hco.ntt.co.jp> Analysed-by: David Gibson <david@gibson.dropbear.id.au> Fixes: 457ff122e33c ("udp,pasta: Periodically scan for ports to automatically forward") Signed-off-by: Stefano Brivio <sbrivio@redhat.com>
Diffstat (limited to 'tap.c')
0 files changed, 0 insertions, 0 deletions