Ssh-copy-id succeeded, but still prompt password input

authenticationpasswordsshsshd

  1. I have ssh-copy-id root@c199 succeeded before.
  2. I can login by ssh root@c199 without password prompt
  3. I want to auto login by another user ufo (remote machine has this user)

  4. ssh-copy-id ufo@c199 ask me enter password, 

    /usr/bin/ssh-copy-id: INFO: attempting to log in with the new key(s), to filter out any that are already installed
/usr/bin/ssh-copy-id: INFO: 1 key(s) remain to be installed -- if you are prompted now it is to install the new keys
ufo@c199's password:

Number of key(s) added: 1

Now try logging into the machine, with:   "ssh 'ufo@c199'"
and check to make sure that only the key(s) you wanted were added.

  5. But login by ssh ufo@c199 still prompt password input .

I try to login remote centos on msys2(on Windows) by ssh , I found there are many same lines like 

ssh-rsa AAAAB3NzaC1yc2EAAAADAQABAAABAQCs7RTfvn83Rxdmvgfh+F4kUlM5FzIUb9rRHaqq11xKIW1gztn/+G4tr+OWl4o6GTW2Z361hIi
ugy8DPtMATN66nTTDUYO0sSvw2BrQfDY4iIENdLpkkHO8KQVGpQE+8tDkaZfD6EQLVtl0uvDE3D77tfcnBLODXgZPQsUSlssMi+pxDbSVjjKgrP
hM1G/L9OTrEHKWDhF+ZBgY1RuLl7ZEdoATbhJaK4FFb9hNn/2CSibVfLts8HJGYQXIQRX/RBzaDZp47sKZvq302ewkkVorNY+c9mmoze6mi8Ip2
zEQOMi6S9zM/yRiD0XZrbmzYfNkoXA03WTmMR/DynVvX2nV /c/Users/xxxx/.ssh/id_rsa

in centos's /home/ufo/.ssh/authorized_keys ,

I have changed .ssh user's folder permissions to 700 and authorized_keys file to 644 .

Same ssh key, ssh root@c199 promptless login , but ssh ufo@c199 prompt password input ..

UPDATE

ssh ufo@c199 -vv output:

....
debug1: Server host key: ecdsa-sha2-nistp256 SHA256:zmCg5vHhBAMd5P4ei82+KsVg072KXbC63C44P0w3zbU
debug1: Host 'c199' is known and matches the ECDSA host key.
debug1: Found key in /c/Users/xxxxx/.ssh/known_hosts:35
debug2: set_newkeys: mode 1
debug1: rekey after 134217728 blocks
debug1: SSH2_MSG_NEWKEYS sent
debug1: expecting SSH2_MSG_NEWKEYS
debug1: SSH2_MSG_NEWKEYS received
debug2: set_newkeys: mode 0
debug1: rekey after 134217728 blocks
debug2: key: /c/Users/xxxxx/.ssh/id_rsa (0x60006bec0), agent
debug2: key: /c/Users/xxxxx/.ssh/id_dsa (0x0)
debug2: key: /c/Users/xxxxx/.ssh/id_ecdsa (0x0)
debug2: key: /c/Users/xxxxx/.ssh/id_ed25519 (0x0)
debug2: service_accept: ssh-userauth
debug1: SSH2_MSG_SERVICE_ACCEPT received
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /c/Users/xxxxx/.ssh/id_rsa
debug2: we sent a publickey packet, wait for reply
debug1: Authentications that can continue: publickey,gssapi-keyex,gssapi-with-mic,password
debug1: Trying private key: /c/Users/xxxxx/.ssh/id_dsa
debug1: Trying private key: /c/Users/xxxxx/.ssh/id_ecdsa
debug1: Trying private key: /c/Users/xxxxx/.ssh/id_ed25519
debug2: we did not send a packet, disable method
debug1: Next authentication method: password

Best Answer

Thanks to https://unix.stackexchange.com/a/55481/106419, which told me how to debug ssh.

To enable ssh debug to see what happen

systemctl stop sshd
/usr/sbin/sshd -d -p 22

I found:

Authentication refused: bad ownership or modes for directory /home/ufo

All guys only told:

  • /home/ufo/.ssh ownership is correct 700
  • /home/ufo/.ssh/authorized_keys ownership is correct 600/644

But sshd still check the user home folder !!! No one mentioned this !

sudo chmod 700 /home/ufo solve this problem.

Summary:

You need ensure:

  • /home/ufo ownership is 700
  • /home/ufo/.ssh ownership is 700
  • /home/ufo/.ssh/authorized_keys ownership is 600

change ufo to you home folder name

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