Arch Linux

android

Member

From: San Diego

Registered: 2003-04-18

Posts: 160

OpenSSH-8 client_loop: send disconnect: Broken pipe

Hello,

This is mostly just as an FYI, as I believe I've found the workaround.

After upgrading to the OpenSSH-8 based client on my workstation machine:

[user@workstation ~]$ ssh -V
OpenSSH_8.1p1, OpenSSL 1.1.1d  10 Sep 2019

I was repeatedly having my login sessions terminated after several hours, with this error at the client end:

client_loop: send disconnect: Broken pipe

In my case, only the client end was updated. The server runs an older version of sshd, which has supported very long term login sessions, until the recent openssh client update.

After some searching, I found this mention in the OpenSSH mailing list:

https://lists.mindrot.org/pipermail/ope … 37714.html

It mentions the ssh client option "-oIPQoS=none".

After logging in with this command line option, my sessions have currently lasted for several days.

Including the IPQoS option text in my search also found this archlinux forum post from last year:

https://bbs.archlinux.org/viewtopic.php?id=240303

Which mentions the IPQoS option set to a different value. Perhaps other IPQoS values other than "none" would solve my disconnections, but I haven't experimented with them.

It also mentions setting the IPQoS option for a specific Host, within the ~/.ssh/config file, instead of entering it on the command line.

Not sure if others have had this issue, but my searches did not turn up much info. So I thought I'd document my findings here, in case others are experiencing this problem.

Best Wishes...

android

android

Member

From: San Diego

Registered: 2003-04-18

Posts: 160

Re: OpenSSH-8 client_loop: send disconnect: Broken pipe

So,

It turns out "-oIPQoS=none" doesn't fix this. 8-(

With additional of -vvvv in the ssh client command, the following debug3 always appears at the time of disconnection:

...
debug3: send packet: type 1
client_loop: send disconnect: Broken pipe

There are no indications in the server logs.

I do connect for long term sessions to other sshd servers that are not affected by this disconnect.

Situation is still unresolved...

seamusdemora

Member

Registered: 2020-04-09

Posts: 17

Re: OpenSSH-8 client_loop: send disconnect: Broken pipe

I've just found your post doing a search to solve the same problem - well, the same *indication* at any rate. I'll assume you've not found a solution, but if you have please let me know. Similarly, if you've moved on, or don't wish to engage on this thread, please advise.

I am trying some things now:

  the sshd/server settings in /etc/ssh/sshd_config :
    TCPKeepAlive yes
    ClientAliveInterval 60
    ClientAliveCountMax 40000

AND

  the ssh/client setting in ~/.ssh/config :
    ServerAliveInterval 60

I had hopes for the `IPQoS` option, but see it didn't work for you. From the manual (man ssh_config):

IPQoS   Specifies the IPv4 type-of-service or DSCP class for connections.  Accepted values are af11,
             af12, af13, af21, af22, af23, af31, af32, af33, af41, af42, af43, cs0, cs1, cs2, cs3, cs4, cs5,
             cs6, cs7, ef, lowdelay, throughput, reliability, a numeric value, or none to use the operating
             system default.  This option may take one or two arguments, separated by whitespace.  If one
             argument is specified, it is used as the packet class unconditionally.  If two values are spec-
             ified, the first is automatically selected for interactive sessions and the second for non-
             interactive sessions.  The default is af21 (Low-Latency Data) for interactive sessions and cs1
             (Lower Effort) for non-interactive sessions. 

Since `none` implies the OS default, it seems there *might* be some hope for this depending on the OS. I'll try it & post here if I learn anything worth reporting.

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https://github.com/seamusdemora