Why does Tor listen to UDP?

Support Relay Operator
1

Hi,

I recently noticed that Tor binds to UDP sockets when configured as a relay on FreeBSD.

root@:~ # sockstat -46l
USER     COMMAND    PID   FD  PROTO  LOCAL ADDRESS         FOREIGN ADDRESS      
_tor     tor         1344 5   tcp4   *:9001                *:*
_tor     tor         1344 6   tcp6   *:9001                *:*
_tor     tor         1344 8   udp4   *:*                   *:*
_tor     tor         1344 9   udp6   *:*                   *:*

I only have the following two lines in torrc:

SOCKSPort 0
ORPort 9001

My understanding is that Tor only binds to UDP when configured to provide DNS, but I don’t have DNSPort set.

So why is Tor binding to UDP sockets?

Thanks!

1 Like
2

Update:

After upgrading to tor 0.4.9.5, the udp4 socket disappears, but the udp6 socket remains. :frowning_face_with_open_mouth: