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WSL2 SSH client hangs during expecting SSH2_MSG_KEX_ECDH_REPLY #9110

Closed
1 of 2 tasks
sxlijin opened this issue Nov 2, 2022 · 5 comments
Closed
1 of 2 tasks

WSL2 SSH client hangs during expecting SSH2_MSG_KEX_ECDH_REPLY #9110

sxlijin opened this issue Nov 2, 2022 · 5 comments

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@sxlijin
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sxlijin commented Nov 2, 2022

Version

Microsoft Windows [Version 10.0.22621.755]

WSL Version

  • WSL 2
  • WSL 1

Kernel Version

Linux version 5.15.68.1-microsoft-standard-WSL2 (oe-user@oe-host) (x86_64-msft-linux-gcc (GCC) 9.3.0, GNU ld (GNU Binutils) 2.34.0.20200220) #1 SMP Mon Sep 19 19:14:52 UTC 2022

Distro Version

Debian

Other Software

Connecting to OpenSSH_8.9p1 Ubuntu-3, OpenSSL 3.0.2 15 Mar 2022

Repro Steps

Repro (for me) consists of ssh me@my-remote-machine. It is 100% reproducible when SSHing from WSL; it is 100% non-reproducible when SSHing from Powershell.

This started happening after I installed the following updates on Windows:

  • Windows Subsystem for Linux Update - 5.10.102.2
  • Windows Subsystem for Linux WSLg Preview - 1.0.27
  • 2022-10 .NET Core 3.1.30 Security Update for x64 Client (KB5019349)
  • 2022-10 Cumulative Update for Windows 11 Version 22H2 for x64-based Systems (KB5018496)
  • 2022-10 Cumulative Update for .NET Framework 3.5 and 4.8.1 for Windows 11, version 22H2 for x64 (KB5017271)

Expected Behavior

ssh client sets up the connection/session

Actual Behavior

ssh client hangs

Diagnostic Logs

SSH server has this log statement spammed every time I attempt to connect from WSL:

Nov 02 12:02:08 my-remote-machine sshd[189234]: fatal: Timeout before authentication for aaa.bbb.ccc.ddd port eeeee

ssh -vvv me@my-remote-machine shows this from WSL:

debug1: Local version string SSH-2.0-OpenSSH_7.9p1 Debian-10+deb10u2
debug1: Remote protocol version 2.0, remote software version OpenSSH_8.9p1 Ubuntu-3
debug1: match: OpenSSH_8.9p1 Ubuntu-3 pat OpenSSH* compat 0x04000000
debug2: fd 3 setting O_NONBLOCK
debug1: Authenticating to my-remote-machine:22 as 'me'
debug3: hostkeys_foreach: reading file "/home/me/.ssh/known_hosts"
debug3: record_hostkey: found key type ECDSA in file /home/me/.ssh/known_hosts:1
debug3: load_hostkeys: loaded 1 keys from sam-dell.trunk.io.beta.tailscale.net
debug3: order_hostkeyalgs: prefer hostkeyalgs: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
debug3: send packet: type 20
debug1: SSH2_MSG_KEXINIT sent
debug3: receive packet: type 20
debug1: SSH2_MSG_KEXINIT received
debug2: local client KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256,diffie-hellman-group14-sha1,ext-info-c
debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519-cert-v01@openssh.com,rsa-sha2-512-cert-v01@openssh.com,rsa-sha2-256-cert-v01@openssh.com,ssh-rsa-cert-v01@openssh.com,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com,zlib
debug2: compression stoc: none,zlib@openssh.com,zlib
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug2: peer server KEXINIT proposal
debug2: KEX algorithms: curve25519-sha256,curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,sntrup761x25519-sha512@openssh.com,diffie-hellman-group-exchange-sha256,diffie-hellman-group16-sha512,diffie-hellman-group18-sha512,diffie-hellman-group14-sha256
debug2: host key algorithms: rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
debug2: ciphers ctos: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: ciphers stoc: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
debug2: MACs ctos: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: MACs stoc: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
debug2: compression ctos: none,zlib@openssh.com
debug2: compression stoc: none,zlib@openssh.com
debug2: languages ctos:
debug2: languages stoc:
debug2: first_kex_follows 0
debug2: reserved 0
debug1: kex: algorithm: curve25519-sha256
debug1: kex: host key algorithm: ecdsa-sha2-nistp256
debug1: kex: server->client cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug1: kex: client->server cipher: chacha20-poly1305@openssh.com MAC: <implicit> compression: none
debug3: send packet: type 30
debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

which suggests that the final packets in the key exchange are getting lost.
@easyteacher
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Usually a MTU problem

@sxlijin
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sxlijin commented Nov 7, 2022

Yeah, a lot of people say that twiddling their MTU on the WSL NICs addresses this. Without being a networking expert, that seems ridiculous to me, and is strongly indicative of something weird in the host->vm networking stack.

@QifanWang
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I just encountered the same issue. I set MTU to 1350 like #4253, and it works.

@microsoft-github-policy-service Microsoft GitHub Policy Service
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This issue has been automatically closed since it has not had any activity for the past year. If you're still experiencing this issue please re-file this as a new issue or feature request.

Thank you!

@stokito
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stokito commented Jul 19, 2024

For me it helped only the reducing list of supported MACs:

ssh example.com -o MACs=hmac-sha2-256

You can add it to the .ssh/config:

Host *
    MACs=hmac-sha2-256

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@stokito @sxlijin @easyteacher @QifanWang