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Tasklist

FS#78180 - [filesystem] Enable net.ipv[46].tcp_mtu_probing

Attached to Project: Arch Linux
Opened by Emil (xexaxo) - Wednesday, 12 April 2023, 14:57 GMT
Last edited by Sébastien Luttringer (seblu) - Tuesday, 15 August 2023, 12:26 GMT
Task Type Feature Request
Category Packages: Core
Status Closed
Assigned To Sébastien Luttringer (seblu)
Architecture All
Severity Low
Priority Normal
Reported Version
Due in Version Undecided
Due Date Undecided
Percent Complete 100%
Votes 0
Private No

Details

Description:

As mentioned in number of articles [1] [2], tcp_mtu_probing=1 is required to detect ICMP black holes. Without it, programs can simply stop working leading to substantial user frustration [3].

In practise the issue is caused by a router/firewall outside of the user knowledge or control. More importantly debugging and tracking this down is fairly time consuming, unless you're a networking expert.

Can we have the option enabled by default on Arch?

Thanks in advance,

Additional info:
* package version(s)
2023.01.31-1

* link to upstream bug report, if any
[1] https://xn--tigreray-i1a.org/english/post/15-the-strange-case-of-the-tcp-black-holes/
[2] https://blog.cloudflare.com/path-mtu-discovery-in-practice/
[3] https://github.com/ValveSoftware/Proton/issues/6260
This task depends upon

Closed by  Sébastien Luttringer (seblu)
Tuesday, 15 August 2023, 12:26 GMT
Reason for closing:  Won't implement
Comment by Toolybird (Toolybird) - Thursday, 13 April 2023, 06:53 GMT
So you want to change an upstream kernel default setting for *everyone* just to satisfy some issue with a game compatibility tool which may or may not be an actual problem? That doesn't seem like the Arch way. It would be interesting to know if other distros change the default, in particular RHEL/Fedora and Debian/Ubuntu. But it sounds like Wiki material to me so I vote against. In fact, there is already an entry [1]

[1] https://wiki.archlinux.org/title/sysctl#Enable_MTU_probing
Comment by Emil (xexaxo) - Tuesday, 18 April 2023, 12:11 GMT
I appreciate the input - both here and in other bugs. Thinking about it a bit more - you have a point. Having this indiscriminately is an overkill, despite the annoyance black holes cause. Especially considering enablement may lead to repeated requests/traffic.

Although the tone in your comment seems very different from previously - from going at me ("So you want ...") to jumping to unnecessary hyperbole ("which may or may not be an actual problem"). Sincerely hope it's just a case of waking up on the wrong side of bed thing.

Thanks again for the input.
Comment by Sébastien Luttringer (seblu) - Tuesday, 15 August 2023, 12:26 GMT
Let me agree with both of you.

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