BackTrack Linux 5 : how to set up sshd

When you start sshd at first time , you’ll see “could not …”.

root@bt:~# sudo /etc/init.d/ssh start * Starting OpenBSD Secure Shell server sshd                                 Could not load host key: /etc/ssh/ssh_host_rsa_key Could not load host key: /etc/ssh/ssh_host_dsa_key                                                                     [ OK ]

make host  keys on BT( Back Track Linux )  w/ ssh-keygen command.

root@bt:~# ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key Generating public/private rsa key pair. Enter passphrase (empty for no passphrase): passphrase Enter same passphrase again: passphrase Your identification has been saved in /etc/ssh/ssh_host_rsa_key. Your public key has been saved in /etc/ssh/ssh_host_rsa_key.pub. The key fingerprint is: xxxxxxxxxxxx root@bt The key's randomart image is: +--[ RSA 2048]----+ |              | |              | |              | | .            | |  o S     | | *o.   .      | |B=Bo. .       | |EX= ..        | |o*oo          | +-----------------+ root@bt:~# root@bt:~# ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key Generating public/private dsa key pair. Enter passphrase (empty for no passphrase): passphrase Enter same passphrase again: passphrase Your identification has been saved in /etc/ssh/ssh_host_dsa_key. Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub. The key fingerprint is xxxxxxxxxxxx root@bt The key's randomart image is: +--[ DSA 1024]----+ |=o..o         | |...oEo        | |  o  o+.      | |   . .++      | | o ..S .   | | o =.o    | |   +.o     | |    ...    | |   ....    | +-----------------+ root@bt:~#

restart sshd

root@bt:~# sudo /etc/init.d/ssh start * Starting OpenBSD Secure Shell server sshd                          [ OK ] root@bt:~#

access to BT from a remote machine..
uhh,,, can’t establish ssh connection..

root@hat1:~# ssh 192.168.11.150 Read from socket failed: Connection reset by peer

try again w/ debug option.

SSH client

root@hat1:~# ssh -vvv 192.168.11.150 OpenSSH_5.8p1 Debian-1ubuntu3, OpenSSL 0.9.8o 01 Jun 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to 192.168.11.150 [192.168.11.150] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/id_rsa type -1 debug1: identity file /root/.ssh/id_rsa-cert type -1 debug1: identity file /root/.ssh/id_dsa type -1 debug1: identity file /root/.ssh/id_dsa-cert type -1 debug1: identity file /root/.ssh/id_ecdsa type -1 debug1: identity file /root/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3p1 Debian-3ubuntu6 debug1: match: OpenSSH_5.3p1 Debian-3ubuntu6 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8p1 Debian-1ubuntu3 debug2: fd 3 setting O_NONBLOCK debug1: SSH2_MSG_KEXINIT sent Read from socket failed: Connection reset by peer

SSH server
nnn,, could not load host key...

root@bt:~# /usr/sbin/sshd -d debug1: sshd version OpenSSH_5.3p1 Debian-3ubuntu6 debug1: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> Could not load host key: /etc/ssh/ssh_host_rsa_key debug1: PEM_read_PrivateKey failed debug1: read PEM private key done: type <unknown> Could not load host key: /etc/ssh/ssh_host_dsa_key debug1: rexec_argv[0]='/usr/sbin/sshd' debug1: rexec_argv[1]='-d' debug1: Bind to port 22 on 0.0.0.0. Server listening on 0.0.0.0 port 22. debug1: Server will not fork when running in debugging mode. debug1: rexec start in 4 out 4 newsock 4 pipe -1 sock 7 debug1: inetd sockets after dupping: 3, 3 Connection from 192.168.11.100 port 39932 debug1: Client protocol version 2.0; client software version OpenSSH_5.8p1 Debian-1ubuntu3 debug1: match: OpenSSH_5.8p1 Debian-1ubuntu3 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.3p1 Debian-3ubuntu6 debug1: permanently_set_uid: 102/65534 debug1: list_hostkey_types: No supported key exchange algorithms debug1: do_cleanup debug1: do_cleanup

SSH server has host keys for sure.

root@bt:~# ls /etc/ssh/ssh_host_* -l -rw------- 1 root root  736 2011-05-22 23:20 /etc/ssh/ssh_host_dsa_key -rw-r--r-- 1 root root  597 2011-05-22 23:20 /etc/ssh/ssh_host_dsa_key.pub -rw------- 1 root root 1743 2011-05-22 23:19 /etc/ssh/ssh_host_rsa_key -rw-r--r-- 1 root root  389 2011-05-22 23:19 /etc/ssh/ssh_host_rsa_key.pub

ah,,, I created host keys w/ passphrase.
The problem is ssh server can’t load host keys w/ passphrase.
So create host keys again w/o passphrase. ( empty )

on ssh server

root@bt:~# ssh-keygen -t rsa -f /etc/ssh/ssh_host_rsa_key Generating public/private rsa key pair. /etc/ssh/ssh_host_rsa_key already exists. Overwrite (y/n)? y Enter passphrase (empty for no passphrase):   <- type enter Enter same passphrase again:  <- type enter Your identification has been saved in /etc/ssh/ssh_host_rsa_key. Your public key has been saved in /etc/ssh/ssh_host_rsa_key.pub. The key fingerprint is: zzzzzzzzzzzzzzzzzzzzzz root@bt The key's randomart image is: +--[ RSA 2048]----+ |              | |    . .    | |   + o   . | |    * .. o| |   . S   o o.o| |    . . . +.+ | |       . oE+..| |       ...o+o | |        o.oo. | +-----------------+ root@bt:~# ssh-keygen -t dsa -f /etc/ssh/ssh_host_dsa_key Generating public/private dsa key pair. /etc/ssh/ssh_host_dsa_key already exists. Overwrite (y/n)? y Enter passphrase (empty for no passphrase):    <- type enter Enter same passphrase again:  <- type enter Your identification has been saved in /etc/ssh/ssh_host_dsa_key. Your public key has been saved in /etc/ssh/ssh_host_dsa_key.pub. The key fingerprint is: zzzzzzzzzzzzzzzzzzzzzzzzzzroot@bt The key's randomart image is: +--[ DSA 1024]----+ |              | |         . .  | |          + o | |         . =  | |   . S .. o ..| | . = = .E  ..| |   . + o ..  .| |    . . ... ..| |     . . .o++.| +-----------------+ root@bt:~#

restart SSH

root@bt:~# /etc/init.d/ssh restart * Restarting OpenBSD Secure Shell server sshd                        [ OK ]

OK . works fine :)

SSH client

root@hat1:~# ssh -vvv 192.168.11.150 OpenSSH_5.8p1 Debian-1ubuntu3, OpenSSL 0.9.8o 01 Jun 2010 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug2: ssh_connect: needpriv 0 debug1: Connecting to 192.168.11.150 [192.168.11.150] port 22. debug1: Connection established. debug1: permanently_set_uid: 0/0 debug1: identity file /root/.ssh/id_rsa type -1 debug1: identity file /root/.ssh/id_rsa-cert type -1 debug1: identity file /root/.ssh/id_dsa type -1 debug1: identity file /root/.ssh/id_dsa-cert type -1 debug1: identity file /root/.ssh/id_ecdsa type -1 debug1: identity file /root/.ssh/id_ecdsa-cert type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.3p1 Debian-3ubuntu6 debug1: match: OpenSSH_5.3p1 Debian-3ubuntu6 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.8p1 Debian-1ubuntu3 debug2: fd 3 setting O_NONBLOCK debug3: load_hostkeys: loading entries for host "192.168.11.150" from file "/root/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /root/.ssh/known_hosts:1 debug3: load_hostkeys: loaded 1 keys debug3: order_hostkeyalgs: prefer hostkeyalgs: ssh-rsa-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug2: kex_parse_kexinit: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa-cert-v01@openssh.com,ssh-rsa-cert-v00@openssh.com,ssh-rsa,ecdsa-sha2-nistp256-cert-v01@openssh.com,ecdsa-sha2-nistp384-cert-v01@openssh.com,ecdsa-sha2-nistp521-cert-v01@openssh.com,ssh-dss-cert-v01@openssh.com,ssh-dss-cert-v00@openssh.com,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib debug2: kex_parse_kexinit: none,zlib@openssh.com,zlib debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: kex_parse_kexinit: diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1,diffie-hellman-group1-sha1 debug2: kex_parse_kexinit: ssh-rsa,ssh-dss debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se debug2: kex_parse_kexinit: aes128-ctr,aes192-ctr,aes256-ctr,arcfour256,arcfour128,aes128-cbc,3des-cbc,blowfish-cbc,cast128-cbc,aes192-cbc,aes256-cbc,arcfour,rijndael-cbc@lysator.liu.se debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: hmac-md5,hmac-sha1,umac-64@openssh.com,hmac-ripemd160,hmac-ripemd160@openssh.com,hmac-sha1-96,hmac-md5-96 debug2: kex_parse_kexinit: none,zlib@openssh.com debug2: kex_parse_kexinit: none,zlib@openssh.com debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: debug2: kex_parse_kexinit: first_kex_follows 0 debug2: kex_parse_kexinit: reserved 0 debug2: mac_setup: found hmac-md5 debug1: kex: server->client aes128-ctr hmac-md5 none debug2: mac_setup: found hmac-md5 debug1: kex: client->server aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug2: dh_gen_key: priv key bits set: 124/256 debug2: bits set: 532/1024 debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Server host key: RSA zzzzzzzzzzzzzzzzzzzzzzzzzzzzzz debug3: load_hostkeys: loading entries for host "192.168.11.150" from file "/root/.ssh/known_hosts" debug3: load_hostkeys: found key type RSA in file /root/.ssh/known_hosts:1 debug3: load_hostkeys: loaded 1 keys debug1: Host '192.168.11.150' is known and matches the RSA host key. debug1: Found key in /root/.ssh/known_hosts:1 debug2: bits set: 492/1024 debug1: ssh_rsa_verify: signature correct debug2: kex_derive_keys debug2: set_newkeys: mode 1 debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug2: set_newkeys: mode 0 debug1: SSH2_MSG_NEWKEYS received debug1: Roaming not allowed by server debug1: SSH2_MSG_SERVICE_REQUEST sent debug2: service_accept: ssh-userauth debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /root/.ssh/id_rsa ((nil)) debug2: key: /root/.ssh/id_dsa ((nil)) debug2: key: /root/.ssh/id_ecdsa ((nil)) debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,password debug3: preferred gssapi-keyex,gssapi-with-mic,publickey,keyboard-interactive,password debug3: authmethod_lookup publickey debug3: remaining preferred: keyboard-interactive,password debug3: authmethod_is_enabled publickey debug1: Next authentication method: publickey debug1: Trying private key: /root/.ssh/id_rsa debug3: no such identity: /root/.ssh/id_rsa debug1: Trying private key: /root/.ssh/id_dsa debug3: no such identity: /root/.ssh/id_dsa debug1: Trying private key: /root/.ssh/id_ecdsa debug3: no such identity: /root/.ssh/id_ecdsa debug2: we did not send a packet, disable method debug3: authmethod_lookup password debug3: remaining preferred: ,password debug3: authmethod_is_enabled password debug1: Next authentication method: password root@192.168.11.150's password: debug3: packet_send2: adding 48 (len 63 padlen 17 extra_pad 64) debug2: we sent a password packet, wait for reply debug1: Authentication succeeded (password). Authenticated to 192.168.11.150 ([192.168.11.150]:22). debug1: channel 0: new [client-session] debug3: ssh_session2_open: channel_new: 0 debug2: channel 0: send open debug1: Requesting no-more-sessions@openssh.com debug1: Entering interactive session. debug2: callback start debug2: client_session2_setup: id 0 debug2: fd 3 setting TCP_NODELAY debug3: packet_set_tos: set IP_TOS 0x10 debug2: channel 0: request pty-req confirm 1 debug1: Sending environment. debug3: Ignored env SHELL debug3: Ignored env TERM debug3: Ignored env XDG_SESSION_COOKIE debug3: Ignored env USER debug3: Ignored env LS_COLORS ################################################################### [*] Welcome to the BackTrack 5 Distribution, Codename "Revolution" [*] Official BackTrack Home Page: http://www.backtrack-linux.org [*] Official BackTrack Training : http://www.offensive-security.com ################################################################### [*] To start a graphical interface, type "startx". [*] The default root password is "toor". Last login: Sun May 22 23:46:12 2011 from 192.168.11.100 debug1: PAM: reinitializing credentials debug1: permanently_set_uid: 0/0 Environment:  LANG=en_US.UTF-8  USER=root  LOGNAME=root  HOME=/root  PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games  MAIL=/var/mail/root  SHELL=/bin/bash  SSH_CLIENT=192.168.11.100 58484 22  SSH_CONNECTION=192.168.11.100 58484 192.168.11.150 22  SSH_TTY=/dev/pts/2  TERM=xterm  XDG_SESSION_COOKIE=zzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz root@bt:~#

SSH Server

root@bt:~# sudo /usr/sbin/sshd -d debug1: sshd version OpenSSH_5.3p1 Debian-3ubuntu6 debug1: read PEM private key done: type RSA debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-2048 debug1: Checking blacklist file /etc/ssh/blacklist.RSA-2048 debug1: private host key: #0 type 1 RSA 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: #1 type 2 DSA debug1: rexec_argv[0]='/usr/sbin/sshd' debug1: rexec_argv[1]='-d' debug1: Bind to port 22 on 0.0.0.0. Server listening on 0.0.0.0 port 22. debug1: Server will not fork when running in debugging mode. debug1: rexec start in 4 out 4 newsock 4 pipe -1 sock 7 debug1: inetd sockets after dupping: 3, 3 Connection from 192.168.11.100 port 58484 debug1: Client protocol version 2.0; client software version OpenSSH_5.8p1 Debian-1ubuntu3 debug1: match: OpenSSH_5.8p1 Debian-1ubuntu3 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.3p1 Debian-3ubuntu6 debug1: permanently_set_uid: 102/65534 debug1: list_hostkey_types: ssh-rsa,ssh-dss debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: client->server aes128-ctr hmac-md5 none debug1: kex: server->client aes128-ctr hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST received debug1: SSH2_MSG_KEX_DH_GEX_GROUP sent debug1: expecting SSH2_MSG_KEX_DH_GEX_INIT debug1: SSH2_MSG_KEX_DH_GEX_REPLY sent debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: KEX done debug1: userauth-request for user root service ssh-connection method none debug1: attempt 0 failures 0 debug1: PAM: initializing for "root" debug1: PAM: setting PAM_RHOST to "192.168.11.100" debug1: PAM: setting PAM_TTY to "ssh" Failed none for root from 192.168.11.100 port 58484 ssh2 debug1: userauth-request for user root service ssh-connection method password debug1: attempt 1 failures 0 debug1: PAM: password authentication accepted for root debug1: do_pam_account: called Accepted password for root from 192.168.11.100 port 58484 ssh2 debug1: monitor_child_preauth: root has been authenticated by privileged process debug1: PAM: establishing credentials debug1: Entering interactive session for SSH2. debug1: server_init_dispatch_20 debug1: server_input_channel_open: ctype session rchan 0 win 1048576 max 16384 debug1: input_session_request debug1: channel 0: new [server-session] debug1: session_new: session 0 debug1: session_open: channel 0 debug1: session_open: session 0: link with channel 0 debug1: server_input_channel_open: confirm session debug1: server_input_global_request: rtype no-more-sessions@openssh.com want_reply 0 debug1: server_input_channel_req: channel 0 request pty-req reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req pty-req debug1: Allocating pty. debug1: session_pty_req: session 0 alloc /dev/pts/2 debug1: SELinux support disabled debug1: server_input_channel_req: channel 0 request env reply 0 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req env debug1: server_input_channel_req: channel 0 request shell reply 1 debug1: session_by_channel: session 0 channel 0 debug1: session_input_channel_req: session 0 req shell debug1: Setting controlling tty using TIOCSCTTY.