Permission denied (publickey,gssapi-keyex,gssapi-with-mic).

[root@master Desktop]# service sshd restart
Stopping sshd:                                             [  OK  ]
Starting sshd:                                             [  OK  ]
[root@master Desktop]# ifconfig
eth0      Link encap:Ethernet  HWaddr 00:0C:29:9E:42:F7  
          inet addr:172.20.10.5  Bcast:172.20.10.15  Mask:255.255.255.240
          inet6 addr: 2409:8934:221a:9aab:20c:29ff:fe9e:42f7/64 Scope:Global
          inet6 addr: fe80::20c:29ff:fe9e:42f7/64 Scope:Link
          UP BROADCAST RUNNING MULTICAST  MTU:1500  Metric:1
          RX packets:72 errors:0 dropped:0 overruns:0 frame:0
          TX packets:58 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:1000 
          RX bytes:11595 (11.3 KiB)  TX bytes:6161 (6.0 KiB)

lo        Link encap:Local Loopback  
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:65536  Metric:1
          RX packets:12 errors:0 dropped:0 overruns:0 frame:0
          TX packets:12 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0 
          RX bytes:720 (720.0 b)  TX bytes:720 (720.0 b)

[root@master Desktop]# ssh 172.20.10.6
Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
[root@master Desktop]# service sshd restart
Stopping sshd:                                             [  OK  ]
Starting sshd:                                             [  OK  ]
[root@master Desktop]# ssh root@salve01
ssh: Could not resolve hostname salve01: Name or service not known
[root@master Desktop]# ssh [email protected]
Permission denied (publickey,gssapi-keyex,gssapi-with-mic).
[root@master Desktop]# chmod 700 /root
[root@master Desktop]# chmod 700 /root/.ssh
[root@master Desktop]# chmod 644 /root/.ssh/authorized_keys
[root@master Desktop]# chmod 600 /root/.ssh/id_rsa
[root@master Desktop]#