Looks to be a "No supported key exchange algorithms [preauth]" problem.
Regenerating the host RSA key with "ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key" fixes the issue Log of failure (pre-keygen) on host: $ sudo /usr/sbin/sshd -p 2222 -D -d -d -d -e debug2: load_server_config: filename /etc/ssh/sshd_config debug2: load_server_config: done config len = 37 debug2: parse_server_config: config /etc/ssh/sshd_config len 37 debug3: /etc/ssh/sshd_config:1 setting PermitRootLogin yes debug3: /etc/ssh/sshd_config:2 setting LogLevel DEBUG3 debug1: sshd version OpenSSH_6.6, OpenSSL 1.0.1f 6 Jan 2014 debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_rsa_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_rsa_key debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_dsa_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_dsa_key debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_ecdsa_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_ecdsa_key debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_ed25519_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_ed25519_key debug1: rexec_argv[0]='/usr/sbin/sshd' debug1: rexec_argv[1]='-p' debug1: rexec_argv[2]='2222' debug1: rexec_argv[3]='-D' debug1: rexec_argv[4]='-d' debug1: rexec_argv[5]='-d' debug1: rexec_argv[6]='-d' debug1: rexec_argv[7]='-e' debug3: oom_adjust_setup Set /proc/self/oom_score_adj from 0 to -1000 debug2: fd 3 setting O_NONBLOCK debug1: Bind to port 2222 on 0.0.0.0. Server listening on 0.0.0.0 port 2222. debug2: fd 4 setting O_NONBLOCK debug3: sock_set_v6only: set socket 4 IPV6_V6ONLY debug1: Bind to port 2222 on ::. Server listening on :: port 2222. 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 37 debug3: ssh_msg_send: type 0 debug3: send_rexec_state: done debug1: rexec start in 5 out 5 newsock 5 pipe -1 sock 8 debug3: recv_rexec_state: entering fd = 5 debug3: ssh_msg_recv entering debug3: recv_rexec_state: done debug2: parse_server_config: config rexec len 37 debug3: rexec:1 setting PermitRootLogin yes debug3: rexec:2 setting LogLevel DEBUG3 debug1: sshd version OpenSSH_6.6, OpenSSL 1.0.1f 6 Jan 2014 debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_rsa_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_rsa_key debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_dsa_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_dsa_key debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_ecdsa_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_ecdsa_key debug3: Truncated RSA1 identifier debug1: key_parse_private2: missing begin marker debug1: key_parse_private_pem: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> debug3: Truncated RSA1 identifier debug3: Could not load "/etc/ssh/ssh_host_ed25519_key" as a RSA1 public key Could not load host key: /etc/ssh/ssh_host_ed25519_key debug1: inetd sockets after dupping: 3, 3 Connection from 192.168.56.1 port 53307 on 192.168.56.101 port 2222 debug1: Client protocol version 2.0; client software version OpenSSH_6.6.1p1 Ubuntu-2ubuntu2 debug1: match: OpenSSH_6.6.1p1 Ubuntu-2ubuntu2 pat OpenSSH* compat 0x04000000 debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_6.6p1 Ubuntu-2ubuntu1 debug2: fd 3 setting O_NONBLOCK debug2: Network child is on pid 3095 debug3: preauth child monitor started debug3: privsep user:group 117:65534 [preauth] debug1: permanently_set_uid: 117/65534 [preauth] debug1: list_hostkey_types: [preauth] No supported key exchange algorithms [preauth] debug1: do_cleanup [preauth] debug3: mm_request_receive entering debug1: do_cleanup debug1: Killing privsep child 3095 -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/708493 Title: Can't login anymore: Read from socket failed: Connection reset by peer To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/openssh/+bug/708493/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
