SSH login without password

Question

I know that you can use ssh-keygen to generate a public/private key pair. Then you can install the public key on a remote server. You can then login without supplying a password. I haven't been successful in setting up key-based authentication. SSH always prompts for a password.

Can someone help me understand the debug information?

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Sever information

Server A

-bash-3.00$ uname -a
SunOS cusd2 5.10 Generic_118833-33 sun4u sparc SUNW,UltraAX-i2

Server B

bash-2.05$ uname -a
SunOS apc_dev1db1 5.9 Generic_118558-27 sun4u sparc SUNW,Sun-Fire-V240

plant key

I've generated the key pair on Server A and then copied the public key to Server B. I then renamed it to authorized_keys.

login with debug info

-bash-3.00$ ssh sybase@apc_dev1db1 -v  
Sun_SSH_1.1, SSH protocols 1.5/2.0, OpenSSL 0x0090704f   
debug1: Reading configuration data /etc/ssh/ssh_config   
debug1: Rhosts Authentication disabled, originating port will not be trusted.  
debug1: ssh_connect: needpriv 0  
debug1: Connecting to apc_dev1db1 [192.168.1.44] port 22.   
debug1: Connection established.    
debug1: identity file /export/home/attlmw1/.ssh/identity type -1  
debug1: identity file /export/home/attlmw1/.ssh/id_rsa type 1  
debug1: identity file /export/home/attlmw1/.ssh/id_dsa type -1   
debug1: Remote protocol version 2.0, remote software version Sun_SSH_1.1  
debug1: no match: Sun_SSH_1.1  
debug1: Enabling compatibility mode for protocol 2.0  
debug1: Local version string SSH-2.0-Sun_SSH_1.1  
debug1: Failed to acquire GSS-API credentials for any mechanisms (No credentials were supplied, or the credentials were unavailable or inaccessible  
Unknown code 0  
)  
debug1: SSH2_MSG_KEXINIT sent  
debug1: SSH2_MSG_KEXINIT received  
debug1: kex: server->client aes128-cbc hmac-md5 none  
debug1: kex: client->server aes128-cbc hmac-md5 none  
debug1: Peer sent proposed langtags, ctos: en-US,es,fr,hi-IN,ja-JP,ko,ko-KR,zh,zh-CN,zh-HK,zh-TW,en-CA,es-MX,fr-CA,ja,th,th-TH,i-default  
debug1: Peer sent proposed langtags, stoc: en-US,es,fr,hi-IN,ja-JP,ko,ko-KR,zh,zh-CN,zh-HK,zh-TW,en-CA,es-MX,fr-CA,ja,th,th-TH,i-default  
debug1: We proposed langtags, ctos: i-default  
debug1: We proposed langtags, stoc: i-default  
debug1: Negotiated lang: i-default  
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST sent  
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP  
debug1: Remote: Negotiated main locale: C  
debug1: Remote: Negotiated messages locale: C  
debug1: dh_gen_key: priv key bits set: 139/256  
debug1: bits set: 1592/3191  
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent  
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY  
debug1: Host 'apc_dev1db1' is known and matches the RSA host key.  
debug1: Found key in /export/home/attlmw1/.ssh/known_hosts:1  
debug1: bits set: 1595/3191  
debug1: ssh_rsa_verify: signature correct  
debug1: newkeys: mode 1  
debug1: SSH2_MSG_NEWKEYS sent  
debug1: expecting SSH2_MSG_NEWKEYS  
debug1: newkeys: mode 0  
debug1: SSH2_MSG_NEWKEYS received  
debug1: done: ssh_kex2.  
debug1: send SSH2_MSG_SERVICE_REQUEST  
debug1: got SSH2_MSG_SERVICE_ACCEPT  
debug1: Authentications that can continue: publickey,password,keyboard-interactive  
debug1: Next authentication method: publickey  
debug1: Trying private key: /export/home/attlmw1/.ssh/identity  
debug1: Trying public key: /export/home/attlmw1/.ssh/id_rsa  
debug1: Authentications that can continue: publickey,password,keyboard-interactive  
debug1: Trying private key: /export/home/attlmw1/.ssh/id_dsa  
debug1: Next authentication method: keyboard-interactive  
Password:  

The permission of related files

bash-2.05$ uname -a  
SunOS apc_dev1db1 5.9 Generic_118558-27 sun4u sparc SUNW,Sun-Fire-V240  
bash-2.05$ ls -ld .ssh/  
drwx------   2 sybase   sybase       512 Sep  6 13:16 .ssh/  
bash-2.05$  
bash-2.05$ ls -l .ssh/authorized_keys  
-rw-------   1 sybase   sybase       224 Sep  6 08:31 .ssh/authorized_keys  


-bash-3.00$ uname -a  
SunOS cusd2 5.10 Generic_118833-33 sun4u sparc SUNW,UltraAX-i2  
-bash-3.00$  
-bash-3.00$ ls -ld .ssh/  
drwx------   2 attlmw1  other        512 Sep  6 08:08 .ssh/  
-bash-3.00$ ls -l .ssh/  
total 6  
-rw-------   1 attlmw1  other        887 Sep  5 18:10 id_rsa  
-rw-r--r--   1 attlmw1  other        223 Sep  5 18:10 id_rsa.pub  
-rw-r--r--   1 attlmw1  other        234 Sep  6 08:08 known_hosts  

Answer 1

Make sure that:

• the authorized_keys has permission 600.
• the sybase's $HOME folder and $HOME/.ssh has permission 700 and owned by sybase.

Also take a look at sshd logs on server B, it will tell you more details.

Answer 2

On solaris, you should set the user's home directory to 755, .ssh directory to 755, and .ssh/authorized_keys to 600.

Answer 3

The problem is on the authorized_keys file.
While planting the publick, the correct action is scp the publick key to remote server and add it to the authorized_keys file.
But what i do is copy the content and paste it to authorized_keys file. On putty this will make the orignal content changed. The orignal line is only one line. But after i copy and paste it turn out to be two lines.

Answer 4

In the future, rather than copying and pasting the key, you may want to use this command instead:

ssh-copy-id

This will allow you to not only copy your public key directory to your authorized_key and set the correct permissions.