[SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

UnwillingFirehose · 2019-05-04 13:08:29

In an effort to analyse traffic more often, and just learn more, I'd like to reduce the amount of unnecessary traffic on my network - so it reduces the "noise" when I'm examining something.

On an Arch system with multiple interfaces it's sending out frequent requests to UDP port 1900, to IP 239.255.255.250, on all interfaces.

This is SSDP / UPnP related, and I've avahi installed but I'm not running avahi-daemon. So this is related to something like Samba or gvfs-smb or smbnetfs or similar, but how I do figure out which? I don't see a way to track this using fuser or lsof... what option am I missing?

Thank you.

Last edited by UnwillingFirehose (2019-05-25 16:04:48)

schard · 2019-05-04 13:28:09

What does ss tell you?

UnwillingFirehose · 2019-05-04 22:25:58

schard wrote:

What does ss tell you?

Nothing - as far as I can tell. "ss" doesn't reveal anything, and grepping the output for "1900" or "ssdp" or "upnp" didn't show anything either.

The same goes for "lsof -i UDP:<src port>"

However, from reading the traffic with tshark the interesting part that stands out is this:

Simple Service Discovery Protocol
M-SEARCH * HTTP/1.1\r\n
[Expert Info (Chat/Sequence): M-SEARCH * HTTP/1.1\r\n]
[M-SEARCH * HTTP/1.1\r\n]
[Severity level: Chat]
[Group: Sequence]
Request Method: M-SEARCH
Request URI: *
Request Version: HTTP/1.1
HOST: 239.255.255.250:1900\r\n
MAN: "ssdp:discover"\r\n
MX: 1\r\n
ST: urn:dial-multiscreen-org:service:dial:1\r\n
USER-AGENT: Chromium/74.0.3729.131 Linux\r\n
\r\n
[Full request URI: http://239.255.255.250:1900*]
[HTTP request 4/4]
[Prev request in frame: 7]

From a quick read of http://www.dial-multiscreen.org/ it looks like this is Chromium seeing if there's any devices on the LAN it can display to.... when I've finally worked through my open tabs I'll close down chromium and see if these packets are still there...

fukawi2 · 2019-05-05 01:03:16

Probably relevant: https://bugs.chromium.org/p/chromium/is … ?id=665572 and http://walkersam.blogspot.com/2018/05/d … oogle.html

To disable the media router feature, launch Chrome and enter chrome://flags/
Search for “media router” and disable the feature.

UnwillingFirehose · 2019-05-11 17:37:02

Thank you very much for posting these, that certainly looks like the solution. While I'm still working through my open tabs ( I know a relaunch *should* bring them back, but still... ) I'll restart and check this works, but it certainly looks like the solution.

fukawi2 · 2019-05-15 03:59:26

Don't forget to edit your first post and mark as solved if you've managed to stop the packets

UnwillingFirehose · 2019-05-25 16:03:13

fukawi2 wrote:

Don't forget to edit your first post and mark as solved if you've managed to stop the packets

That's an excellent point, thank you for the reminder.

For those of you reading this in the future - I'm pretty sure I did the following:

* Went to chrome://flags/
* Disabled "Load Media Router Component Extension"
* Disabled "Connect to Cast devices on all IP addresses"

And then, as far as I remember, it just worked. I didn't have restart chromium. I'm about 94 tabs away from being able to do that right now... ( I know they should all come back, but still... )

krlabs · 2025-04-27 16:24:02

This problem is not solved. Google Chrome continues to generate excessive SSDP traffic even after disabling these features. Just open Wireshark and see.

At the moment, this is the only thing that has solved the problem for me:

iptables -I OUTPUT -p udp --dport 1900 -j REJECT

Last edited by krlabs (2025-04-27 16:34:48)

Arch Linux

#1 2019-05-04 13:08:29

[SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#2 2019-05-04 13:28:09

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#3 2019-05-04 22:25:58

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#4 2019-05-05 01:03:16

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#5 2019-05-11 17:37:02

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#6 2019-05-15 03:59:26

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#7 2019-05-25 16:03:13

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

#8 2025-04-27 16:24:02

Re: [SOLVED]Outbound broadcasts to UDP port 1900, what is generating them?

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