Bug#867033: Openssh Server causes Server Hang

No logs were left on the client.

However, strange parts of the sshd debug log have been identified.

--------------------------------------- /var/log/auth.log -------------------

Jul 10 19:55:37 debian systemd-logind[481]: Watching system buttons on /dev/input/event4 (Power Button)

Jul 10 19:55:37 debian sshd[468]: Server listening on 0.0.0.0 port 22.

Jul 10 19:55:37 debian sshd[468]: Server listening on :: port 22.

Jul 10 19:55:37 debian sshd[468]: Received SIGHUP; restarting.

Jul 10 19:55:37 debian sshd[468]: Server listening on 0.0.0.0 port 22.

Jul 10 19:55:37 debian sshd[468]: Server listening on :: port 22.

Jul 10 19:55:39 debian sshd[755]: Accepted password for koov from 192.168.0.2 port 2741 ssh2

Jul 10 19:55:40 debian sshd[755]: pam_unix(sshd:session): session opened for user koov by (uid=0)

Jul 10 19:55:40 debian systemd-logind[481]: New session 1 of user koov.

Jul 10 19:55:40 debian systemd: pam_unix(systemd-user:session): session opened for user koov by (uid=0)

Jul 10 19:57:33 debian sshd[471]: Server listening on 0.0.0.0 port 22.

Jul 10 19:57:33 debian sshd[471]: Server listening on :: port 22.

Jul 10 19:57:33 debian systemd-logind[483]: New seat seat0.

Jul 10 19:57:33 debian systemd-logind[483]: Watching system buttons on /dev/input/event4 (Power Button)

Jul 10 19:57:34 debian sshd[471]: Received SIGHUP; restarting.

Jul 10 19:57:34 debian sshd[471]: Server listening on 0.0.0.0 port 22.

Jul 10 19:57:34 debian sshd[471]: Server listening on :: port 22.

Jul 10 19:58:04 debian login[484]: pam_unix(login:session): session opened for user root by LOGIN(uid=0)

Jul 10 19:58:04 debian systemd-logind[483]: New session 1 of user root.

Jul 10 19:58:04 debian systemd: pam_unix(systemd-user:session): session opened for user root by (uid=0)

Jul 10 19:58:04 debian login[760]: ROOT LOGIN on '/dev/tty1'

Jul 10 19:59:14 debian sshd[471]: Received signal 15; terminating.

Jul 10 19:59:14 debian sshd[781]: debug1: Set /proc/self/oom_score_adj from 0 to -1000

Jul 10 19:59:14 debian sshd[781]: debug1: Bind to port 22 on 0.0.0.0.

Jul 10 19:59:14 debian sshd[781]: Server listening on 0.0.0.0 port 22.

Jul 10 19:59:14 debian sshd[781]: debug1: Bind to port 22 on ::.

Jul 10 19:59:14 debian sshd[781]: Server listening on :: port 22.

Jul 10 19:59:29 debian sshd[781]: debug1: Forked child 788.

Jul 10 19:59:29 debian sshd[788]: debug1: Set /proc/self/oom_score_adj to 0

Jul 10 19:59:29 debian sshd[788]: debug1: rexec start in 5 out 5 newsock 5 pipe 7 sock 8

Jul 10 19:59:29 debian sshd[788]: debug1: inetd sockets after dupping: 3, 3

Jul 10 19:59:29 debian sshd[788]: Connection from 192.168.0.2 port 2786 on 192.168.0.226 port 22

Jul 10 19:59:29 debian sshd[788]: debug1: Client protocol version 2.0; client software version nsssh2_5.0.0039 NetSarang Computer, Inc.

Jul 10 19:59:29 debian sshd[788]: debug1: no match: nsssh2_5.0.0039 NetSarang Computer, Inc.

Jul 10 19:59:29 debian sshd[788]: debug1: Local version string SSH-2.0-OpenSSH_7.4p1 Debian-10

Jul 10 19:59:29 debian sshd[788]: debug1: Enabling compatibility mode for protocol 2.0

Jul 10 19:59:29 debian sshd[788]: debug1: permanently_set_uid: 107/65534 [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: list_hostkey_types: ssh-rsa,rsa-sha2-512,rsa-sha2-256,ecdsa-sha2-nistp256,ssh-ed25519 [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: SSH2_MSG_KEXINIT sent [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: SSH2_MSG_KEXINIT received [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: kex: algorithm: curve25519-sha256@libssh.org [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: kex: host key algorithm: ssh-rsa [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: kex: client->server cipher: aes128-gcm@openssh.com MAC: <implicit> compression: none [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: kex: server->client cipher: aes128-gcm@openssh.com MAC: <implicit> compression: none [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: expecting SSH2_MSG_KEX_ECDH_INIT [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: rekey after 4294967296 blocks [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: SSH2_MSG_NEWKEYS sent [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: expecting SSH2_MSG_NEWKEYS [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: SSH2_MSG_NEWKEYS received [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: rekey after 4294967296 blocks [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: KEX done [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: userauth-request for user koov service ssh-connection method none [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: attempt 0 failures 0 [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: PAM: initializing for "koov"

Jul 10 19:59:29 debian sshd[788]: debug1: PAM: setting PAM_RHOST to "192.168.0.2"

Jul 10 19:59:29 debian sshd[788]: debug1: PAM: setting PAM_TTY to "ssh"

Jul 10 19:59:29 debian sshd[788]: debug1: userauth-request for user koov service ssh-connection method password [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: attempt 1 failures 0 [preauth]

Jul 10 19:59:29 debian sshd[788]: debug1: PAM: password authentication accepted for koov

Jul 10 19:59:29 debian sshd[788]: debug1: do_pam_account: called

Jul 10 19:59:29 debian sshd[788]: Accepted password for koov from 192.168.0.2 port 2786 ssh2

Jul 10 19:59:29 debian sshd[788]: debug1: monitor_child_preauth: koov has been authenticated by privileged process

Jul 10 19:59:29 debian sshd[788]: debug1: monitor_read_log: child log fd closed

Jul 10 19:59:29 debian sshd[788]: debug1: PAM: establishing credentials

Jul 10 19:59:29 debian sshd[788]: pam_unix(sshd:session): session opened for user koov by (uid=0)

Jul 10 19:59:29 debian systemd-logind[483]: New session 3 of user koov.

Jul 10 19:59:29 debian systemd: pam_unix(systemd-user:session): session opened for user koov by (uid=0)

Jul 10 19:59:29 debian sshd[788]: User child is on pid 797

Jul 10 19:59:29 debian sshd[797]: debug1: SELinux support disabled

Jul 10 19:59:29 debian sshd[797]: debug1: PAM: establishing credentials

Jul 10 19:59:29 debian sshd[797]: debug1: permanently_set_uid: 1000/1000

Jul 10 19:59:29 debian sshd[797]: debug1: rekey after 4294967296 blocks

Jul 10 19:59:29 debian sshd[797]: debug1: ssh_packet_set_postauth: called

Jul 10 19:59:29 debian sshd[797]: debug1: Entering interactive session for SSH2.

Jul 10 19:59:29 debian sshd[797]: debug1: server_init_dispatch

Jul 10 19:59:29 debian sshd[797]: debug1: server_input_channel_open: ctype session rchan 0 win 32768 max 16384

Jul 10 19:59:29 debian sshd[797]: debug1: input_session_request

Jul 10 19:59:29 debian sshd[797]: debug1: channel 0: new [server-session]

Jul 10 19:59:29 debian sshd[797]: debug1: session_new: session 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_open: channel 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_open: session 0: link with channel 0

Jul 10 19:59:29 debian sshd[797]: debug1: server_input_channel_open: confirm session

Jul 10 19:59:29 debian sshd[797]: debug1: server_input_channel_req: channel 0 request x11-req reply 1

Jul 10 19:59:29 debian sshd[797]: debug1: session_by_channel: session 0 channel 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_input_channel_req: session 0 req x11-req

Jul 10 19:59:29 debian sshd[797]: debug1: channel 1: new [X11 inet listener]

Jul 10 19:59:29 debian sshd[797]: debug1: channel 2: new [X11 inet listener]

Jul 10 19:59:29 debian sshd[797]: debug1: server_input_channel_req: channel 0 request pty-req reply 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_by_channel: session 0 channel 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_input_channel_req: session 0 req pty-req

Jul 10 19:59:29 debian sshd[797]: debug1: Allocating pty.

Jul 10 19:59:29 debian sshd[788]: debug1: session_new: session 0

Jul 10 19:59:29 debian sshd[788]: debug1: SELinux support disabled

Jul 10 19:59:29 debian sshd[797]: debug1: session_pty_req: session 0 alloc /dev/pts/0

Jul 10 19:59:29 debian sshd[797]: debug1: server_input_channel_req: channel 0 request shell reply 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_by_channel: session 0 channel 0

Jul 10 19:59:29 debian sshd[797]: debug1: session_input_channel_req: session 0 req shell

Jul 10 19:59:29 debian sshd[797]: Starting session: shell on pts/0 for koov from 192.168.0.2 port 2786 id 0

Jul 10 19:59:29 debian sshd[799]: debug1: Setting controlling tty using TIOCSCTTY.

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Jul 10 20:00:20 debian systemd-logind[505]: Watching system buttons on /dev/input/event4 (Power Button)

Jul 10 20:00:21 debian sshd[486]: debug1: Set /proc/self/oom_score_adj from 0 to -1000

Jul 10 20:00:21 debian sshd[486]: debug1: Bind to port 22 on 0.0.0.0.

Jul 10 20:00:21 debian sshd[486]: Server listening on 0.0.0.0 port 22.

Jul 10 20:00:21 debian sshd[486]: debug1: Bind to port 22 on ::.

Jul 10 20:00:21 debian sshd[486]: Server listening on :: port 22.

Jul 10 20:00:21 debian sshd[486]: Received SIGHUP; restarting.

Jul 10 20:00:21 debian sshd[486]: debug1: Set /proc/self/oom_score_adj to 0

Jul 10 20:00:21 debian sshd[486]: debug1: Set /proc/self/oom_score_adj from 0 to -1000

Jul 10 20:00:21 debian sshd[486]: debug1: Bind to port 22 on 0.0.0.0.

Jul 10 20:00:21 debian sshd[486]: Server listening on 0.0.0.0 port 22.

Jul 10 20:00:21 debian sshd[486]: debug1: Bind to port 22 on ::.

Jul 10 20:00:21 debian sshd[486]: Server listening on :: port 22.

Jul 10 20:00:29 debian login[507]: pam_unix(login:session): session opened for user root by LOGIN(uid=0)

Jul 10 20:00:29 debian systemd-logind[505]: New session 1 of user root.

Jul 10 20:00:29 debian systemd: pam_unix(systemd-user:session): session opened for user root by (uid=0)

Jul 10 20:00:30 debian login[782]: ROOT LOGIN on '/dev/tty1'

Jul 10 20:03:58 debian sshd[484]: debug1: Set /proc/self/oom_score_adj from 0 to -1000

Jul 10 20:03:58 debian sshd[484]: debug1: Bind to port 22 on 0.0.0.0.

Jul 10 20:03:58 debian sshd[484]: Server listening on 0.0.0.0 port 22.

Jul 10 20:03:58 debian sshd[484]: debug1: Bind to port 22 on ::.

Jul 10 20:03:58 debian sshd[484]: Server listening on :: port 22.

Jul 10 20:03:59 debian systemd-logind[486]: New seat seat0.

Jul 10 20:03:59 debian systemd-logind[486]: Watching system buttons on /dev/input/event4 (Power Button)

Jul 10 20:03:59 debian sshd[484]: Received SIGHUP; restarting.

Jul 10 20:03:59 debian sshd[484]: debug1: Set /proc/self/oom_score_adj to 0

Jul 10 20:03:59 debian sshd[484]: debug1: Set /proc/self/oom_score_adj from 0 to -1000

Jul 10 20:03:59 debian sshd[484]: debug1: Bind to port 22 on 0.0.0.0.

Jul 10 20:03:59 debian sshd[484]: Server listening on 0.0.0.0 port 22.

------------------------------------- end of /var/log/auth.log ---------------------------------------

Jul 10 19:59:29 This is where the system hangs while trying to log in.

Strangely, the ^@ mark was printed too much.

And I force rebooted Jul 10 20:00:20

I hope it helps.