[Bug 708493] Re: cannot login anymore: Read from socket failed: Connection reset by peer

[Ralf Hildebrandt]

So I ran sshd on the target machine in a debugger:


# gdb /usr/sbin/sshd 
GNU gdb (GDB) 7.0.1-debian
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License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
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This GDB was configured as "i486-linux-gnu".
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<http://www.gnu.org/software/gdb/bugs/>...

warning: The current binary is a PIE (Position Independent Executable), which
GDB does NOT currently support.  Most debugger features will fail if used
in this session.

Reading symbols from /usr/sbin/sshd...(no debugging symbols found)...done.
(gdb) set args -dddd -p22222
(gdb) run
Starting program: /usr/sbin/sshd -dddd -p22222
debug2: load_server_config: filename /etc/ssh/sshd_config
debug2: load_server_config: done config len = 637
debug2: parse_server_config: config /etc/ssh/sshd_config len 637
debug3: /etc/ssh/sshd_config:5 setting Port 22
debug3: /etc/ssh/sshd_config:9 setting Protocol 2
debug3: /etc/ssh/sshd_config:11 setting HostKey /etc/ssh/ssh_host_key
debug3: /etc/ssh/sshd_config:13 setting HostKey /etc/ssh/ssh_host_rsa_key
debug3: /etc/ssh/sshd_config:14 setting HostKey /etc/ssh/ssh_host_dsa_key
debug3: /etc/ssh/sshd_config:16 setting UsePrivilegeSeparation yes
debug3: /etc/ssh/sshd_config:19 setting KeyRegenerationInterval 3600
debug3: /etc/ssh/sshd_config:20 setting ServerKeyBits 768
debug3: /etc/ssh/sshd_config:23 setting SyslogFacility AUTH
debug3: /etc/ssh/sshd_config:24 setting LogLevel INFO
debug3: /etc/ssh/sshd_config:27 setting LoginGraceTime 600
debug3: /etc/ssh/sshd_config:28 setting PermitRootLogin yes
debug3: /etc/ssh/sshd_config:29 setting StrictModes yes
debug3: /etc/ssh/sshd_config:31 setting RSAAuthentication yes
debug3: /etc/ssh/sshd_config:32 setting PubkeyAuthentication yes
debug3: /etc/ssh/sshd_config:36 setting IgnoreRhosts yes
debug3: /etc/ssh/sshd_config:38 setting RhostsRSAAuthentication no
debug3: /etc/ssh/sshd_config:40 setting HostbasedAuthentication no
debug3: /etc/ssh/sshd_config:45 setting PermitEmptyPasswords no
debug3: /etc/ssh/sshd_config:51 setting PasswordAuthentication yes
debug3: /etc/ssh/sshd_config:62 setting X11Forwarding yes
debug3: /etc/ssh/sshd_config:63 setting X11DisplayOffset 10
debug3: /etc/ssh/sshd_config:64 setting PrintMotd no
debug3: /etc/ssh/sshd_config:65 setting PrintLastLog yes
debug3: /etc/ssh/sshd_config:66 setting TCPKeepAlive yes
debug3: /etc/ssh/sshd_config:72 setting Subsystem sftp /usr/lib/openssh/sftp-server
debug3: /etc/ssh/sshd_config:74 setting UsePAM yes
debug1: sshd version OpenSSH_5.5p1 Debian-6
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-1024
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-1024
debug1: private host key: #0 type 0 RSA1
debug3: Not a RSA1 key file /etc/ssh/ssh_host_rsa_key.
debug1: read PEM private key done: type RSA
debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-1024
debug1: Checking blacklist file /etc/ssh/blacklist.RSA-1024
debug1: private host key: #1 type 1 RSA
debug3: Not a RSA1 key file /etc/ssh/ssh_host_dsa_key.
debug1: read PEM private key done: type DSA
debug1: Checking blacklist file /usr/share/ssh/blacklist.DSA-1024
debug1: Checking blacklist file /etc/ssh/blacklist.DSA-1024
debug1: private host key: #2 type 2 DSA
debug1: rexec_argv[0]='/usr/sbin/sshd'
debug1: rexec_argv[1]='-dddd'
debug1: rexec_argv[2]='-p22222'
debug3: oom_adjust_setup
Set /proc/self/oom_adj from 0 to -17
debug2: fd 3 setting O_NONBLOCK
debug1: Bind to port 22222 on 0.0.0.0.
Server listening on 0.0.0.0 port 22222.
debug2: fd 4 setting O_NONBLOCK
debug3: sock_set_v6only: set socket 4 IPV6_V6ONLY
debug1: Bind to port 22222 on ::.
Server listening on :: port 22222.


debug3: fd 5 is not O_NONBLOCK
debug1: Server will not fork when running in debugging mode.
debug3: send_rexec_state: entering fd = 8 config len 637
debug3: ssh_msg_send: type 0
debug3: send_rexec_state: done
debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8
Executing new program: /usr/sbin/sshd
warning: The current binary is a PIE (Position Independent Executable), which
GDB does NOT currently support.  Most debugger features will fail if used
in this session.

debug1: inetd sockets after dupping: 3, 3
Connection from 172.28.0.5 port 58160
Did not receive identification string from 172.28.0.5

Program exited with code 0377.


So when logging in, the sshd process is just exiting.

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https://bugs.launchpad.net/bugs/708493

Title:
  cannot login anymore: Read from socket failed: Connection reset by
  peer