# Syncthing on Port 5351
**URL:** https://forum.syncthing.net/t/syncthing-on-port-5351/16617
**Category:** Support
**Created:** [April 5, 2021, 3:08pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617 "2021-04-05T15:08:04Z")
**Posts on this page:** 14
**Page:** 1
### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 3:08pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/1 "2021-04-05T15:08:04Z")
I have three computers using syncthing, all working fine. Syncthing seem to want to send a lot of traffic to port 5351 on my firewall. What is it trying to do, is it necessary, and how do I shut it off?
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### Author:  [@canton7](https://forum.syncthing.net/u/canton7)
#### Post date: [April 5, 2021, 3:39pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/2 "2021-04-05T15:39:49Z")
Syncthing doesn’t use port 5351, and I can’t see any relays running on that port.
Are you sure that Syncthing is attempting to connect to that port?
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### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 3:41pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/3 "2021-04-05T15:41:05Z")
Yes. I ran “lsof | grep 5351” and caught it in the act.
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### Author:  [@canton7](https://forum.syncthing.net/u/canton7)
#### Post date: [April 5, 2021, 3:42pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/4 "2021-04-05T15:42:03Z")
Could you post exactly what that printed?
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### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 3:44pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/5 "2021-04-05T15:44:20Z")
```
$ lsof | grep 5351
lsof: WARNING: can't stat() tracefs file system /sys/kernel/debug/tracing
Output information may be incomplete.
syncthing 1189 charles 58u IPv4 669777 0t0 UDP hawk.localdomain:60722->freeman.localdomain:5351
syncthing 1189 1190 syncthing charles 58u IPv4 669777 0t0 UDP hawk.localdomain:60722->freeman.localdomain:5351
syncthing 1189 1191 syncthing charles 58u IPv4 669777 0t0 UDP hawk.localdomain:60722->freeman.localdomain:5351
syncthing 1189 1192 syncthing charles 58u IPv4 669777 0t0 UDP hawk.localdomain:60722->freeman.localdomain:5351
syncthing 1189 1193 syncthing charles 58u IPv4 669777 0t0 UDP hawk.localdomain:60722->freeman.localdomain:5351
....
```
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### Author:  [@canton7](https://forum.syncthing.net/u/canton7)
#### Post date: [April 5, 2021, 3:50pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/6 "2021-04-05T15:50:06Z")
I don’t suppose you’ve configured freeman.localdomain to listen on port 5351? Or configured Syncthing on that machine to connect to freeman.localdomain on port 5351?
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### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 3:52pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/7 "2021-04-05T15:52:16Z")
freeman is the firewall. Syncthing doesn’t run on it. freeman doesn’t have anything on it that uses port 5351, so it blocks that port.
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### Author:  [@canton7](https://forum.syncthing.net/u/canton7)
#### Post date: [April 5, 2021, 3:59pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/8 "2021-04-05T15:59:38Z")
You’ve tried grepping Syncthing’s config.xml for “5351” I assume?
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### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 4:00pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/9 "2021-04-05T16:00:09Z")
Yes, both of them. No show.
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### Author:  [@canton7](https://forum.syncthing.net/u/canton7)
#### Post date: [April 5, 2021, 4:04pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/10 "2021-04-05T16:04:02Z")
D’oh, 5351 is NAT-PMP. Settings → Connections → Uncheck “Enable NAT traversal” I guess?
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### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 4:13pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/11 "2021-04-05T16:13:21Z")
Well, I tried that. We will see if that makes a difference. I also shut off global discovery and enable relaying. I don’t know what they do, so I don’t think I need them.
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### Author:  [@canton7](https://forum.syncthing.net/u/canton7)
#### Post date: [April 5, 2021, 4:15pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/12 "2021-04-05T16:15:38Z")
Global discovery is used to let devices which aren’t on the same LAN find each others’ addresses (local discovery is used if they are on the same LAN). Relaying is used if two devices can’t connect directly.
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### Author:  [@ccurley](https://forum.syncthing.net/u/ccurley)
#### Post date: [April 5, 2021, 6:10pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/13 "2021-04-05T18:10:47Z")
Ah, thank you. About what I figured when I looked at them.
Two hours on, and freeman is not reporting any new packets at 5351. I think that does it. Thank you.
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### Author:  [@system](https://forum.syncthing.net/u/system)
#### Post date: [May 5, 2021, 6:11pm UTC](https://forum.syncthing.net/t/syncthing-on-port-5351/16617/14 "2021-05-05T18:11:35Z")
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