I have configured sshd to accept key-based ssh logins with LogLevel on DEBUG, and uploaded my public key to ~/.ssh.authorized_keys, where permissions are set as:
700 ~/.ssh 600 ~/.ssh/authorized_keys
From root, I can su - USERNAME. From the client I get Permission denied (publicly). From the server Here's how it is telling me that it "Could not open authorized keys '/home/USERNAME/.ssh/authorized_keys': Permission denied".
Client protocol version 2.0; client software version OpenSSH_5.2 match: OpenSSH_5.2 pat OpenSSH* Enabling compatibility mode for protocol 2.0 Local version string SSH-2.0-OpenSSH_5.9p1 Debian-5ubuntu1 permanently_set_uid: 105/65534 [preauth] list_hostkey_types: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256 [preauth] SSH2_MSG_KEXINIT sent [preauth] SSH2_MSG_KEXINIT received [preauth] kex: client->server aes128-ctr hmac-md5 none [preauth] kex: server->client aes128-ctr hmac-md5 none [preauth] SSH2_MSG_KEX_DH_GEX_REQUEST received [preauth] SSH2_MSG_KEX_DH_GEX_GROUP sent [preauth] expecting SSH2_MSG_KEX_DH_GEX_INIT [preauth] SSH2_MSG_KEX_DH_GEX_REPLY sent [preauth] SSH2_MSG_NEWKEYS sent [preauth] expecting SSH2_MSG_NEWKEYS [preauth] SSH2_MSG_NEWKEYS received [preauth] KEX done [preauth] userauth-request for user USERNAME service ssh-connection method none [preauth] attempt 0 failures 0 [preauth] PAM: initializing for "USERNAME" PAM: setting PAM_RHOST to "USERHOSTNAME" PAM: setting PAM_TTY to "ssh" userauth_send_banner: sent [preauth] userauth-request for user USERNAME service ssh-connection method publickey [preauth] attempt 1 failures 0 [preauth] test whether pkalg/pkblob are acceptable [preauth] Checking blacklist file /usr/share/ssh/blacklist.RSA-4096 Checking blacklist file /etc/ssh/blacklist.RSA-4096 temporarily_use_uid: 1001/1002 (e=0/0) trying public key file /home/USERNAME/.ssh/authorized_keys Could not open authorized keys '/home/USERNAME/.ssh/authorized_keys': Permission denied restore_uid: 0/0 temporarily_use_uid: 1001/1002 (e=0/0) trying public key file /home/USERNAME/.ssh/authorized_keys2 Could not open authorized keys '/home/USERNAME/.ssh/authorized_keys2': Permission denied restore_uid: 0/0 Failed publickey for USERNAME from IPADDRESS port 57523 ssh2 Connection closed by IPADDRESS [preauth] do_cleanup [preauth] monitor_read_log: child log fd closed do_cleanup PAM: cleanup