Hi Nick,

> On 19. Nov 2025, at 18:00, Nick Weaver <nweaver@gmail.com> wrote:
>> On Nov 19, 2025, at 7:31 AM, Sebastian Hahn via tor-relays <tor-relays@lists.torproject.org> wrote:
>>
>> I'm one of the people responsible for flagging old versions as a
>> dirauth operator. Please do not treat this flagging as anything
>> more than a friendly nudge to update. If there are more serious
>> issues or the version is so outdated that it isn't maintained
>> anymore at all, we can exclude the relays from the consensus as a
>> more drastic measure.
>>
>> Ideally, your distribution updates quickly, you notice that
>> automatically, and then apply the update soon.
>
> Except the problem:  When you flag an old version then the client appears to no longer accept it as a guard node (it is how I noticed).
>
> By doing so, within <24 hours of new version release, you are eliminating >1/2+ of the potential guard nodes in the network.  It is not a "polite nudge", but something that potentially disrupts the network.

If this were true, I would be concerned, but it is not according to my
testing. My Tor Browser happily continues using a guard which has not
yet updated to the latest version.

> I'm too lazy to trace the Tor source code (I have a moral obligation not to try to read too much ugly C that wants to be C++ and has >2500 GOTO statements), but I use my relay as a pinned guard for a test-server (with an override so it accepts just a single guard for a hidden service).

My experiment above didn't consider non-standard configurations, but,
as far as I can tell, you're seeing something else. A quick grep through
the source code also doesn't appear to indicate differently.

> When the node gets the "Not recommended" flag, it is no longer considered usable as a guard and I get a continuous stream of:

The proper way to implement that would be by just not assigning the
guard flag to the offending relays, which isn't done.

>
> Nov 14 17:44:21.000 [notice] Failed to find node for hop #1 of our path. Discarding this circuit.
>
>
> errors in the log.
>
> There probably needs to be a stated policy on "Absent a security vulnerability of severity X, older server versions are not deprecated for Y days" to prevent this from potentially disrupting the network.

I currently do not see any need for such a policy and will, for the time
being, continue to follow the suggestions of the network team for
version recommendations.

Cheers
Sebastian
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