[Bug 1874257] Re: SSH fails with connection timed out - in VPN and hangs here "expecting SSH2_MSG_KEX_ECDH_REPLY" + Ubuntu 16.04.6 LTS

Lucas Kanashiro 1874257 at bugs.launchpad.net
Tue Apr 12 19:40:31 UTC 2022 

@family-gan are you saying this is an issue in Ubuntu Impish (21.10)? It
seems to be already fixed in supported releases. Could you share any
steps to reproduce it? If you consider the issue you are facing
different than the one discussed in this bug please consider filing a
separate bug.

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Title:
  SSH fails with connection timed out - in VPN and hangs here "expecting
  SSH2_MSG_KEX_ECDH_REPLY" + Ubuntu 16.04.6 LTS

Status in linux package in Ubuntu:
  Invalid
Status in openconnect package in Ubuntu:
  Fix Released
Status in openssh package in Ubuntu:
  Invalid
Status in openconnect source package in Xenial:
  Confirmed

Bug description:
  Hello Team,

  SSH timeout issue, once connect to VPN.

  Environment

  ======
  Dell XPS 9570 
  Ubuntu 16.04.6 Xenial Xerus)
  kernel - 4.15.0-55-generic

  $dpkg -l | grep -i openssh
  ii  openssh-client     1:7.2p2-4ubuntu2.8  --> 
  ii  openssh-server     1:7.2p2-4ubuntu2.8          
  ii  openssh-sftp-server  1:7.2p2-4ubuntu2.8        

  
  VPN tunnel info 
  ====
  vpn0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
            inet addr:IP  P-t-P:xx  Mask:255.255.252.0
            inet6 addr: fe80::b8e2:bea4:2e62:fe08/64 Scope:Link
            UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1406  Metric:1
            RX packets:962 errors:0 dropped:0 overruns:0 frame:0
            TX packets:1029 errors:0 dropped:0 overruns:0 carrier:0
            collisions:0 txqueuelen:500
            RX bytes:87839 (87.8 KB)  TX bytes:238740 (238.7 KB)

  Issue
  ====
  Unable to connect to any host via ssh or sftp after VPN connection 

  Tried 
  =====

  Reinstalled the openssh-client package and still no luck. May I know
  why the default cipher is not taking/hanging? Please let me know .
  There were no recent changes.

  
  Workaround
  ===
  Able to connect to ssh / sftp $ssh -c aes128-ctr   user at IP

  
  Below is the debug ssh client logs ===
  ======

  $ssh -vvv  user at ip
  OpenSSH_7.2p2 Ubuntu-4ubuntu2.8, OpenSSL 1.0.2g  1 Mar 2016
  debug1: Reading configuration data /etc/ssh/ssh_config
  debug1: /etc/ssh/ssh_config line 19: Applying options for *
  debug2: resolving "IP" port 22
  debug2: ssh_connect_direct: needpriv 0
  debug1: Connecting to IP [IP] port 22.
  debug1: Connection established.
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_rsa type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_rsa-cert type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_dsa type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_dsa-cert type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_ecdsa type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_ed25519 type -1
  debug1: key_load_public: No such file or directory
  debug1: identity file /home/user/.ssh/id_ed25519-cert type -1
  debug1: Enabling compatibility mode for protocol 2.0
  debug1: Local version string SSH-2.0-OpenSSH_7.2p2 Ubuntu-4ubuntu2.8
  debug1: Remote protocol version 2.0, remote software version OpenSSH_7.6p1 Ubuntu-4ubuntu0.3
  debug1: match: OpenSSH_7.6p1 Ubuntu-4ubuntu0.3 pat OpenSSH* compat 0x04000000
  debug2: fd 3 setting O_NONBLOCK
  debug1: Authenticating to IP:22 as 'user'
  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 at libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,ext-info-c
  debug2: host key algorithms: ecdsa-sha2-nistp256-cert-v01 at openssh.com,ecdsa-sha2-nistp384-cert-v01 at openssh.com,ecdsa-sha2-nistp521-cert-v01 at openssh.com,ssh-ed25519-cert-v01 at openssh.com,ssh-rsa-cert-v01 at openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-ed25519,rsa-sha2-512,rsa-sha2-256,ssh-rsa
  debug2: ciphers ctos: chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
  debug2: ciphers stoc: chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com,aes128-cbc,aes192-cbc,aes256-cbc,3des-cbc
  debug2: MACs ctos: umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
  debug2: MACs stoc: umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
  debug2: compression ctos: none,zlib at openssh.com,zlib
  debug2: compression stoc: none,zlib at 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 at 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
  debug2: host key algorithms: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519
  debug2: ciphers ctos: chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com
  debug2: ciphers stoc: chacha20-poly1305 at openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm at openssh.com,aes256-gcm at openssh.com
  debug2: MACs ctos: umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
  debug2: MACs stoc: umac-64-etm at openssh.com,umac-128-etm at openssh.com,hmac-sha2-256-etm at openssh.com,hmac-sha2-512-etm at openssh.com,hmac-sha1-etm at openssh.com,umac-64 at openssh.com,umac-128 at openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
  debug2: compression ctos: none,zlib at openssh.com
  debug2: compression stoc: none,zlib at openssh.com
  debug2: languages ctos:
  debug2: languages stoc:
  debug2: first_kex_follows 0
  debug2: reserved 0
  debug1: kex: algorithm: curve25519-sha256 at libssh.org
  debug1: kex: host key algorithm: ecdsa-sha2-nistp256
  debug1: kex: server->client cipher: chacha20-poly1305 at openssh.com MAC: <implicit> compression: none
  debug1: kex: client->server cipher: chacha20-poly1305 at openssh.com MAC: <implicit> compression: none
  debug3: send packet: type 30
  debug1: expecting SSH2_MSG_KEX_ECDH_REPLY

  << Hangs here >>

  Please shed some views

  Thanks
  Jay

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