Path: csiph.com!eternal-september.org!feeder.eternal-september.org!nntp.eternal-september.org!.POSTED!not-for-mail
From: TheLastSysop <thelastsysop@dev.null>
Newsgroups: comp.os.linux.misc
Subject: Re: A small pre-fix checklist for sick Linux boxes
Date: Wed, 10 Jun 2026 00:39:10 GMT
Organization: The Null Device Restoration Society
Lines: 56
Message-ID: <86b1f593985a91ed9467@dev.null>
References: <0af9a3a88b1e5798c4f3@dev.null> <110ab05$ckmk$10@dont-email.me>
Injection-Date: Wed, 10 Jun 2026 00:39:11 +0000 (UTC)
Injection-Info: dont-email.me; logging-data="443290"; mail-complaints-to="abuse@eternal-september.org";	posting-account="U2FsdGVkX1+mp6zVF4rknvmwhT48RKqrs7+PDLLElPs="; posting-host="4a3ff1ddd4520e0e3b411fbbfc126362"
Cancel-Lock: sha1:S9zslSkYhOBBPrLQmS+JQTlh73Q= sha256:MHF1qjnzw/C3Hg+cfH20mEoVtls6wwCcmbnVj0lPQuE= sha1:de9Y4A+I9/3ju6/MFcdn5nQllKc=
X-Archive-Policy: please preserve the funny parts
X-Mood: reasonably caffeinated
In-Reply-To: <110ab05$ckmk$10@dont-email.me>
X-Newsreader: tin can + wet string 0.9.7
X-Operating-System: TempleOS-adjacent abacus cluster
Xref: csiph.com comp.os.linux.misc:87772

>On Wed, 10 Jun 2026 00:26:46 -0000 (UTC), Lawrence
>=?iso-8859-13?q?D=FFOliveiro?= <ldo@nz.invalid> wrote:
>On Tue, 09 Jun 2026 20:28:55 GMT, TheLastSysop wrote:
>
>> uname -a
>> ip addr
>> ip route
>> systemctl --failed
>> journalctl -b -p warning..alert --no-pager | tail -100
>> df -h
>> lsblk -f
>
>Does that look as intended?
>
>> If it is a network problem, I add:
>>
>> ss -tulpn
>> resolvectl status
>
>That’s a new one on me ...
>
>Ah. Not used in Debian.
><https://www.freedesktop.org/software/systemd/man/latest/resolvectl.html>
>
>> That little text file often makes the difference between "I changed
>> six things and now it is worse" and "the default route disappeared
>> after the VPN came up".
>
>Typically I would look more specifically at settings around the
>reported symptoms, rather than trying to wade through screeds of
>generic listings as the above commands would produce.
>
>E.g. Does the post-up script for the OpenVPN connection overwrite
>the wrong default routing setup?

Fair point.  I would not treat the list as a replacement for chasing the
reported symptom; it is more of a quick baseline before changing anything. For a
VPN/routing complaint, the useful subset would be closer to:

    ip route get 1.1.1.1
    ip route show table all
    ip rule show
    resolvectl status    # only when systemd-resolved is actually in use

On Debian systems not using systemd-resolved, `resolvectl` can be replaced by
boring checks such as `getent hosts example.com` and looking at
`/etc/resolv.conf` to see who owns DNS at that moment.

And yes, for OpenVPN specifically I would look at the up/down scripts and
compare routes before and after connection.  A single overenthusiastic
`redirect-gateway` or post-up command can make the rest of the machine look
haunted.

-- 
TheLastSysop <thelastsysop@dev.null>
"I survived the great rm -rf / rehearsal and all I got was this .signature."