SSH Keys set up and logs show successful, but still prompting for password?

▲
0
▼

This has never worked correctly I don't think. I can't recall, just have been inputting password all this time. I admin ten load balanced servers, but I am accessing them internally via internal ip's. When I ssh-copy-id my key to the remote system, it looks like it successfully authenticates, yet still prompts me for a password. My .ssh folder has perms of 600, only known_hosts has 644, and other servers that keys work on have the same perms. /var/log/secure says it was accepted. All perms in /etc/ssh/* are 644. Any ideas? Thank you in advance!

**/var/log/secure**
Jul 25 07:30:55 X sshd[25970]: Accepted password for user from 172.29.2.133 port 23423 ssh2
Jul 25 07:30:55 X sshd[25970]: pam_unix(sshd:session): session opened for user user by (uid=0)
Jul 25 07:37:27 X sudo: pam_unix(sudo:auth): conversation failed
Jul 25 07:37:27 X sudo: pam_unix(sudo:auth): auth could not identify password for [user]
Jul 25 07:38:15 X sudo:   user: TTY=pts/1 ; PWD=/home/user ; USER=root ; COMMAND=/usr/bin/less /var/log/secure

**ssh -v output**
OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014                                                            
debug1: Reading configuration data /etc/ssh/ssh_config                                              
debug1: /etc/ssh/ssh_config line 29: Applying options for *                                         
debug1: Connecting to X [172.20.2.131] port 22.                                              
debug1: Connection established.                                                                     
debug1: identity file /home/user/.ssh/id_rsa type 1                                               
debug1: identity file /home/user/.ssh/id_rsa-cert type -1                                         
debug1: identity file /home/user/.ssh/id_dsa type -1                                              
debug1: identity file /home/user/.ssh/id_dsa-cert type -1                                         
debug1: identity file /home/user/.ssh/id_ecdsa type -1                                            
debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1                                       
debug1: client_input_channel_req: channel 0 rtype exit-status reply 0                               
debug1: channel 0: free: client-session, nchannels 1                                                
Connection to X closed.                                                                      
Transferred: sent 11752, received 9832 bytes, in 262.0 seconds                                      
Bytes per second: sent 44.9, received 37.5                                                          
debug1: Exit status 0                                                                               
user@AUR-000229:/mnt/c/Users/user$ ssh -v X
OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014                                                            
debug1: Reading configuration data /etc/ssh/ssh_config                                              
debug1: /etc/ssh/ssh_config line 29: Applying options for *                                         
debug1: Connecting to X [172.20.2.131] port 22.                                              
debug1: Connection established.                                                                     
debug1: identity file /home/user/.ssh/id_rsa type 1                                               
debug1: identity file /home/user/.ssh/id_rsa-cert type -1                                         
debug1: identity file /home/user/.ssh/id_dsa type -1                                              
debug1: identity file /home/user/.ssh/id_dsa-cert type -1                                         
debug1: identity file /home/user/.ssh/id_ecdsa type -1                                            
debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1                                       
debug1: identity file /home/user/.ssh/id_ed25519 type -1                                          
debug1: identity file /home/user/.ssh/id_ed25519-cert type -1                                     
debug1: Enabling compatibility mode for protocol 2.0                                                
debug1: Local version string SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8                              
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3                            
debug1: match: OpenSSH_4.3 pat OpenSSH_4* compat 0x00000000                                         
debug1: SSH2_MSG_KEXINIT sent                                                                       
debug1: SSH2_MSG_KEXINIT received                                                                   
debug1: kex: server->client aes128-ctr hmac-md5 none                                                
debug1: kex: client->server aes128-ctr hmac-md5 none                                                
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<3072<8192) sent                                            
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP                                                         
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent                                                               
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY                                                         
debug1: Server host key: RSA 8a:0f:76:f8:55:e7:65:25:10:ae:f3:d9:3c:dd:48:0a                        
debug1: Host 'X' is known and matches the RSA host key.                                      
debug1: Found key in /home/user/.ssh/known_hosts:10                                               
debug1: ssh_rsa_verify: signature correct                                                           
debug1: SSH2_MSG_NEWKEYS sent                                                                       
debug1: expecting SSH2_MSG_NEWKEYS                                                                  
debug1: SSH2_MSG_NEWKEYS received                                                                   
debug1: SSH2_MSG_SERVICE_REQUEST sent                                                               
debug1: SSH2_MSG_SERVICE_ACCEPT received                                                            
debug1: Authentications that can continue: password                                                 
debug1: Next authentication method: password                                                        
user@X's password:                                                                         
debug1: Authentication succeeded (password).                                                        
Authenticated to X ([172.20.2.131]:22).                                                      
debug1: channel 0: new [client-session]                                                             
debug1: Entering interactive session.                                                               
debug1: Sending environment.                                                                        
debug1: Sending env LANG = en_US.UTF-8                                                              
Last login: Tue Jul 25 07:26:18 2017 from 172.29.2.133   



**Another server who with the same setup, keys work.**
OpenSSH_6.6.1, OpenSSL 1.0.1f 6 Jan 2014

debug1: Reading configuration data /etc/ssh/ssh_config
debug1: /etc/ssh/ssh_config line 29: Applying options for *
debug1: Connecting to X [172.20.2.132] port 22.
debug1: Connection established.
debug1: identity file /home/user/.ssh/id_rsa type 1
debug1: identity file /home/user/.ssh/id_rsa-cert type -1
debug1: identity file /home/user/.ssh/id_dsa type -1
debug1: identity file /home/user/.ssh/id_dsa-cert type -1
debug1: identity file /home/user/.ssh/id_ecdsa type -1
debug1: identity file /home/user/.ssh/id_ecdsa-cert type -1
debug1: identity file /home/user/.ssh/id_ed25519 type -1
debug1: identity file /home/user/.ssh/id_ed25519-cert type -1
debug1: Enabling compatibility mode for protocol 2.0
debug1: Local version string SSH-2.0-OpenSSH_6.6.1p1 Ubuntu-2ubuntu2.8
debug1: Remote protocol version 2.0, remote software version OpenSSH_4.3
debug1: match: OpenSSH_4.3 pat OpenSSH_4* compat 0x00000000
debug1: SSH2_MSG_KEXINIT sent
debug1: SSH2_MSG_KEXINIT received
debug1: kex: server->client aes128-ctr hmac-md5 none
debug1: kex: client->server aes128-ctr hmac-md5 none
debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<3072<8192) sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP
debug1: SSH2_MSG_KEX_DH_GEX_INIT sent
debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY
debug1: Server host key: RSA 15:5c:e0:96:15:6c:18:85:e8:e8:86:ab:3a:e7:7e:b7
debug1: Host 'X' is known and matches the RSA host key.
debug1: Found key in /home/user/.ssh/known_hosts:25
debug1: ssh_rsa_verify: signature correct
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug1: SSH2_MSG_SERVICE_REQUEST sent
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-with-mic,password
debug1: Next authentication method: gssapi-with-mic
debug1: Unspecified GSS failure.  Minor code may provide more information
No Kerberos credentials available

debug1: Unspecified GSS failure.  Minor code may provide more information
No Kerberos credentials available

debug1: Unspecified GSS failure.  Minor code may provide more information


debug1: Unspecified GSS failure.  Minor code may provide more information
No Kerberos credentials available

debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/user/.ssh/id_rsa
debug1: Server accepts key: pkalg ssh-rsa blen 279
debug1: key_parse_private2: missing begin marker
debug1: read PEM private key done: type RSA
debug1: Authentication succeeded (publickey).
Authenticated to X ([172.20.2.132]:22).
debug1: channel 0: new [client-session]
debug1: Entering interactive session.
debug1: Sending environment.
debug1: Sending env LANG = en_US.UTF-8
Last login: Tue Jul 25 07:27:19 2017 from 172.29.2.133
redhat-enterprise-linux
openssh
ssh-keys
asked on Super User Jul 25, 2017 by Kyle H • edited Jul 25, 2017 by Kyle H

2 Answers

▲
1
▼

Not to contradict anyone, but if the server is only ever prompting for password authentication, your client won't offer a key.

In your debug above:

debug1: Authentications that can continue: password
debug1: Next authentication method: password
user@X's password:
debug1: Authentication succeeded (password).
Authenticated to X ([172.20.2.131]:22).

The server you're connecting to does not offer you (the client) to provide a PSK. The server's sshd_config must have the following:

PubkeyAuthentication yes

AuthorizedKeysFile .ssh/authorized_keys

For comparison, this is my ssh debug output for a server the correctly is willing to accept publickey authentication:

debug1: Authentications that can continue: publickey,keyboard-interactive

debug1: Next authentication method: publickey

debug1: Offering RSA public key: imported-openssh-key

debug1: Server accepts key: pkalg rsa-sha2-512 blen 151

debug1: Single to Multithread CTR cipher swap - client request

debug1: Authentication succeeded (publickey).

-- sorry for poor formating --

answered on Super User Jul 25, 2017 by Joey
▲
0
▼

As Datmocc suggests, check the ownership of the authorized_keys file on the server, as well as the ownership of the id_rsa file locally. You should also ensure only the owner has read permission (chmod 400 <file>). Take a look at the log output for sshd on the server when it starts up, it will complain if there is a problem with these permissions.

The debug log for your ssh session shows it is not providing the private key for authentication (as suggested in your question heading), and by the looks of it your server is not even advertising it will accept private key authentication. A debug log of a successful private-key authentication session should contain something like:

debug1: Authentications that can continue: publickey,**others
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/user/.ssh/id_rsa
debug1: Server accepts key: pkalg rsa-sha2-512 blen 407
debug1: Authentication succeeded (publickey).

Until the server states Authentications that can continue: publickey, your client will never offer one.

answered on Super User Jul 25, 2017 by Liam Dennehy

User contributions licensed under CC BY-SA 3.0