SSH: Permission denied — causes and solutions

Summary

The error "Permission denied (publickey,password)" during SSH connection means the server rejected authentication. Check the password, keys, file permissions, and SSH server settings.

Applies to:
✔ VPS
✔ Dedicated servers
✔ Linux

Connect with debug output

ssh -v root@SERVER_IP

The output will show at which stage authentication failed.

Cause 1: wrong password

Make sure you're entering the correct password. Note:

• Characters are not displayed when typing the password
• Check keyboard layout and Caps Lock

If the password is lost, reset it via VNC/IPMI console:

passwd root

Cause 2: password authentication disabled

Via VNC/IPMI console, check SSH settings:

grep -E "PasswordAuthentication|PermitRootLogin" /etc/ssh/sshd_config

If PasswordAuthentication no, password login is disabled. To temporarily enable:

sed -i "s/PasswordAuthentication no/PasswordAuthentication yes/" /etc/ssh/sshd_config

systemctl restart sshd

Cause 3: wrong SSH key

If using a key, make sure the public part is added on the server:

cat ~/.ssh/authorized_keys

Check which key the client is offering:

ssh -v root@SERVER_IP 2>&1 | grep "Offering"

Cause 4: wrong file permissions

chmod 700 /root/.ssh

chmod 600 /root/.ssh/authorized_keys

chown -R root:root /root/.ssh

Cause 5: AllowUsers/AllowGroups directive

grep -E "AllowUsers|AllowGroups|DenyUsers" /etc/ssh/sshd_config

If AllowUsers is specified and root is not listed, add it:

AllowUsers root yourusername

systemctl restart sshd

Cause 6: PermitRootLogin disabled

grep PermitRootLogin /etc/ssh/sshd_config

If the value is no, change to yes or prohibit-password:

sed -i "s/PermitRootLogin no/PermitRootLogin yes/" /etc/ssh/sshd_config

systemctl restart sshd

Verification

ssh root@SERVER_IP

If the connection still fails after all checks, open a support ticket. Include:
- output of ssh -v root@IP
- contents of /etc/ssh/sshd_config (if accessible via VNC/IPMI)