I cannot get sshd to read authorized_keys (see auth.log dump for more) and thus it won't allow RSA-based connections. I'm stuck with password log-in (and trying to transition away from that). It claims that the authorized_keys file does not exist. It does (exist) and is accessible by (600). sshd has NOT been added to (it's a standard Ubuntu Server 12.04 install). Changes to the dumps, etc. (below): OpenSSH user: (user name is of the form "abcd-efgh", btw) OpenSSH user's group: (i.e., same name as user, standard Ubuntu install) OpenSSH client ip: OpenSSH server hostname: System Info: This is a new Ubuntu Server (12.04) install. All patches have been applied (as of the timestamps you see below). This is a "textbook" installation and I can log in with password fine (and then sudo). root is as configured by Ubuntu installer (not using it directly). The machine ONLY has OpenSSH installed (i.e., choose OpenSSH in Ubuntu Installation and nothing else). OpenSSH on the machine is accessible via direct and network interfaces (but RSA-based auth fails always). Not using DSA. Not allowing OpenSSH v1. It shouldn't matter, but... I'm connecting (via TCP) from a Windows 7 client via PuTTY (with Pageant configured to present the private key, etc.). The private key (.ppk form) is a "textbook" password protected, RSA-2, 1024b key. Files Info: /home/ is 750 /home//.ssh is 700 (was 750) /home//.ssh/authorized_keys is 600 (was 640) ALL of those directories/files are owned by and (i.e., standard Ubuntu Server installation stuff) authorized_keys HAS a single, valid ssh-rsa key line plus one \n (atend). There are no extra chars at the start of the file (i.e., first char is 's' of ssh-rsa) There are NO other files in ~/.ssh/ Dump of (relevant part of) auth.log ---------- May 19 12:22:06 sshd[7558]: debug1: userauth-request for user service ssh-connection method none [prea uth] May 19 12:22:06 sshd[7558]: debug1: attempt 0 failures 0 [preauth] May 19 12:22:27 sshd[7558]: debug1: PAM: initializing for "" May 19 12:22:27 sshd[7558]: debug1: PAM: setting PAM_RHOST to "" May 19 12:22:27 sshd[7558]: debug1: PAM: setting PAM_TTY to "ssh" May 19 12:22:27 sshd[7558]: debug1: userauth-request for user service ssh-connection method publickey [preauth] May 19 12:22:27 sshd[7558]: debug1: attempt 1 failures 0 [preauth] May 19 12:22:27 sshd[7558]: debug1: test whether pkalg/pkblob are acceptable [preauth] May 19 12:22:27 sshd[7558]: debug1: Checking blacklist file /usr/share/ssh/blacklist.RSA-1024 May 19 12:22:27 sshd[7558]: debug1: Checking blacklist file /etc/ssh/blacklist.RSA-1024 May 19 12:22:27 sshd[7558]: debug1: temporarily_use_uid: 1000/1000 (e=0/0) May 19 12:22:27 sshd[7558]: debug1: trying public key file /home//.ssh/authorized_keys May 19 12:22:27 sshd[7558]: debug1: Could not open authorized keys '/home//.ssh/authorized_keys': No su ch file or directory May 19 12:22:27 sshd[7558]: debug1: restore_uid: 0/0 May 19 12:22:27 sshd[7558]: Failed publickey for from port 55099 ssh2 Dump of sshd_config: ---------- # Package generated configuration file # See the sshd_config(5) manpage for details # What ports, IPs and protocols we listen for Port 22 # Use these options to restrict which interfaces/protocols sshd will bind to #ListenAddress :: #ListenAddress 0.0.0.0 Protocol 2 # HostKeys for protocol version 2 HostKey /etc/ssh/ssh_host_rsa_key #HostKey /etc/ssh/ssh_host_dsa_key #HostKey /etc/ssh/ssh_host_ecdsa_key #Privilege Separation is turned on for security UsePrivilegeSeparation yes # Lifetime and size of ephemeral version 1 server key KeyRegenerationInterval 3600 ServerKeyBits 768 # Logging SyslogFacility AUTH LogLevel VERBOSE # Authentication: LoginGraceTime 120 PermitRootLogin no StrictModes yes RSAAuthentication yes PubkeyAuthentication yes #AuthorizedKeysFile %h/.ssh/authorized_keys # Don't read the user's ~/.rhosts and ~/.shosts files IgnoreRhosts yes # For this to work you will also need host keys in /etc/ssh_known_hosts RhostsRSAAuthentication no # similar for protocol version 2 HostbasedAuthentication no # Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication #IgnoreUserKnownHosts yes # To enable empty passwords, change to yes (NOT RECOMMENDED) PermitEmptyPasswords no # Change to yes to enable challenge-response passwords (beware issues with # some PAM modules and threads) ChallengeResponseAuthentication no # Change to no to disable tunnelled clear text passwords #PasswordAuthentication yes # Kerberos options #KerberosAuthentication no #KerberosGetAFSToken no #KerberosOrLocalPasswd yes #KerberosTicketCleanup yes # GSSAPI options #GSSAPIAuthentication no #GSSAPICleanupCredentials yes X11Forwarding no X11DisplayOffset 10 PrintMotd no PrintLastLog yes TCPKeepAlive yes #UseLogin no #MaxStartups 10:30:60 #Banner /etc/issue.net # Allow client to pass locale environment variables AcceptEnv LANG LC_* Subsystem sftp /usr/lib/openssh/sftp-server # Set this to 'yes' to enable PAM authentication, account processing, # and session processing. If this is enabled, PAM authentication will # be allowed through the ChallengeResponseAuthentication and # PasswordAuthentication. Depending on your PAM configuration, # PAM authentication via ChallengeResponseAuthentication may bypass # the setting of "PermitRootLogin without-password". # If you just want the PAM account and session checks to run without # PAM authentication, then enable this but set PasswordAuthentication # and ChallengeResponseAuthentication to 'no'. UsePAM yes # Restrict access to the following user(s). #AllowUsers

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