# Why does Tor listen to UDP?

**URL:** https://forum.torproject.org/t/why-does-tor-listen-to-udp/21284
**Category:** Relay Operator
**Tags:** tor
**Created:** [February 26, 2026, 3:09am UTC](https://forum.torproject.org/t/why-does-tor-listen-to-udp/21284 "2026-02-26T03:09:45Z")
**Posts on this page:** 2
**Page:** 1

<div class="post-metadata">

### Author: ![dudu](https://forum.torproject.org/letter_avatar_proxy/v4/letter/d/3ec8ea/32.png) [@dudu](https://forum.torproject.org/u/dudu)
#### Post date: [February 26, 2026, 3:09am UTC](https://forum.torproject.org/t/why-does-tor-listen-to-udp/21284/1 "2026-02-26T03:09:45Z")

</div>

Hi,

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

```auto
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`:

```auto
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!

---

<div class="post-metadata">

### Author: ![dudu](https://forum.torproject.org/letter_avatar_proxy/v4/letter/d/3ec8ea/32.png) [@dudu](https://forum.torproject.org/u/dudu)
#### Post date: [March 28, 2026, 6:51pm UTC](https://forum.torproject.org/t/why-does-tor-listen-to-udp/21284/2 "2026-03-28T18:51:24Z")

</div>

**Update:**

* * *

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