I've tried to setup a password-less ssh b/w A to B and B to A as well. Generated the public and private key using ssh-keygen -trsa on both the machines. Used the ssh-copy-id utility to copy the public-keys from A to B as well as B to A. The passwordless ssh works from A to B but not from B to A. I've checked the permissions of the ~/ssh/ folder and seems to be normal. A's .ssh folder permissions: -rw------- 1 root root 13530 2011-07-26 23:00 known_hosts -rw------- 1 root root 403 2011-07-27 00:35 id_rsa.pub -rw------- 1 root root 1675 2011-07-27 00:35 id_rsa -rw------- 1 root root 799 2011-07-27 00:37 authorized_keys drwxrwx--- 70 root root 4096 2011-07-27 00:37 .. drwx------ 2 root root 4096 2011-07-27 00:38 . B's .ssh folder permissions: -rw------- 1 root root 884 2011-07-07 13:15 known_hosts -rw-r--r-- 1 root root 396 2011-07-27 00:15 id_rsa.pub -rw------- 1 root root 1675 2011-07-27 00:15 id_rsa -rw------- 1 root root 2545 2011-07-27 00:36 authorized_keys drwxr-xr-x 8 root root 4096 2011-07-06 19:44 .. drwx------ 2 root root 4096 2011-07-27 00:15 . A is an ubuntu 10.04 (OpenSSH_5.3p1 Debian-3ubuntu4, OpenSSL 0.9.8k 25 Mar 2009) B is a debian machine (OpenSSH_5.1p1 Debian-5, OpenSSL 0.9.8g 19 Oct 2007) From A: #ssh B works fine. From B: #ssh -vvv A ... ... debug1: SSH2_MSG_SERVICE_ACCEPT received debug2: key: /root/.ssh/identity ((nil)) debug2: key: /root/.ssh/id_rsa (0x7f1581f23a50) debug2: key: /root/.ssh/id_dsa ((nil)) debug3: Wrote 64 bytes for a total of 1127 debug1: Authentications that can continue: publickey,password debug3: start over, passed a different list publickey,password debug3: preferred gssapi-keyex,gssapi-with-mic,gssapi,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/identity debug3: no such identity: /root/.ssh/identity debug1: Offering public key: /root/.ssh/id_rsa debug3: send_pubkey_test debug2: we sent a publickey packet, wait for reply debug3: Wrote 368 bytes for a total of 1495 debug1: Authentications that can continue: publickey,password debug1: Trying private key: /root/.ssh/id_dsa debug3: no such identity: /root/.ssh/id_dsa 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 [email protected]'s password: Which essentially means it's not authenticating using the file /root/id_rsa. I ran the ssh-add command in both the machines as well. The authentication part of /etc/ssh/sshd_config file is # Authentication: LoginGraceTime 120 PermitRootLogin yes StrictModes yes RSAAuthentication yes PubkeyAuthentication yes #AuthorizedKeysFile %h/.ssh/authorized_keys # Don't read the user's ~/.rhosts and ~/.shosts files I'm running out of ideas. Any help would be appreciated.