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Groups > linux.debian.kernel > #79639

Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts

From Hauke Fath <hf@spg.tu-darmstadt.de>
Newsgroups linux.debian.bugs.dist, linux.debian.kernel
Subject Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts
Date 2023-07-18 12:40 +0200
Message-ID <GSQhz-145h-9@gated-at.bofh.it> (permalink)
References (3 earlier) <GSevD-GCQ-3@gated-at.bofh.it> <GSqGt-NYJ-1@gated-at.bofh.it> <GSBix-UDB-3@gated-at.bofh.it> <GNRnX-2WoE-3@gated-at.bofh.it> <GSBix-UDB-3@gated-at.bofh.it>
Organization TU Darmstadt, Nachrichtentechnik

Cross-posted to 2 groups.

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On 7/17/23 20:29, Ben Hutchings wrote:
>> But the router's package filter will have lost state after a reboot,
>> and reject packets from tcp connections that the clients assume to
>> exist. This is not a problem with udp, because connection-less.
 >
> Ah, I see.  You didn't mention that there was dynamic NAT involved
> before.

Because it isn't. What is involved is a stateful packet filter (FreeBSD 
pf). I said

| We run nfs through a router (several client subnets accessing servers
| in an internal server subnet), and found nfs over udp a lot more
| robust in the face or router reboots.

> If an NFS server is rebooted abruptly (so it doesn't properly close TCP
> connections), once it's back up it will respond to any requests from
> clients with a TCP RST, and they should reconnect.

Understood, and not relevant here.

> If a NAT router between client and server is rebooted, I think that
> something similar should happen, but the router would need to send the
> TCP RST instead.

After a router reboot, the stateful packet filter will have lost 
information on active tcp connections, and (rightfully) reject packets 
for what the nfs clients (rightfully) see as an existing connection.

> Is your router configured to send a TCP RST when receiving a packet for
> an unknown connection, or does it just drop those packets?  (In
> iptables this is the difference between REJECT and DROP policies.)

The router defaults to returning RST.

Anyway: I am not asking for an udp default here, but simply for Debian 
to keep providing the _option_, and leave the decision to me, the admin.

Cheerio,
Hauke


-- 
      The ASCII Ribbon Campaign                    Hauke Fath
()     No HTML/RTF in email	        Institut für Nachrichtentechnik
/\     No Word docs in email                     TU Darmstadt
      Respect for open standards              Ruf +49-6151-16-21344

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Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Hauke Fath <hf@spg.tu-darmstadt.de> - 2023-07-04 18:50 +0200
  Processed: Re: Bug#1040343: linux-image-5.10.0-9-amd64: Kernel  silenty de-supported nfsv3 UDP mounts "Debian Bug Tracking System" <owner@bugs.debian.org> - 2023-07-05 10:30 +0200
  Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Bastian Blank <waldi@debian.org> - 2023-07-05 10:30 +0200
    Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Hauke Fath <hf@spg.tu-darmstadt.de> - 2023-07-05 15:40 +0200
      Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Ben Hutchings <ben@decadent.org.uk> - 2023-07-16 20:20 +0200
        Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Hauke Fath <hf@spg.tu-darmstadt.de> - 2023-07-17 09:20 +0200
          Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Ben Hutchings <ben@decadent.org.uk> - 2023-07-17 20:40 +0200
            Bug#1040343: linux-image-5.10.0-9-amd64: Kernel silenty de-supported nfsv3 UDP mounts Hauke Fath <hf@spg.tu-darmstadt.de> - 2023-07-18 12:40 +0200
  Bug#1040343: marked as done (linux-image-5.10.0-9-amd64: Kernel  silenty de-supported nfsv3 UDP mounts) "Debian Bug Tracking System" <owner@bugs.debian.org> - 2023-07-05 14:40 +0200

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