Member Avatar for Tinnin

Hi All,

I'm trying to setup ssh key authentication on a git server and remove the password authentication. The server and any clients are all local at the moment. The clients are running Windows 7.

I've got the ssh key part set up but I'm having trouble preventing the password authentication if no keys are found on the client.

/etc/ssh/sshd_config:

# Package generated configuration file
# See the sshd_config(5) manpage for details

# What ports, IPs and protocols we listen for
Port 22
# Use these options to restrict which interfaces/protocols sshd will bind to
#ListenAddress ::
#ListenAddress 0.0.0.0
Protocol 2
# HostKeys for protocol version 2
HostKey /etc/ssh/ssh_host_rsa_key
HostKey /etc/ssh/ssh_host_dsa_key
HostKey /etc/ssh/ssh_host_ecdsa_key
HostKey /etc/ssh/ssh_host_ed25519_key
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes

# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 1024

# Logging
SyslogFacility AUTH
LogLevel INFO

# Authentication:
LoginGraceTime 120
PermitRootLogin without-password
StrictModes yes

RSAAuthentication yes
PubkeyAuthentication yes
#AuthorizedKeysFile     %h/.ssh/authorized_keys

# Don't read the user's ~/.rhosts and ~/.shosts files
IgnoreRhosts yes
# For this to work you will also need host keys in /etc/ssh_known_hosts
RhostsRSAAuthentication no
# similar for protocol version 2
HostbasedAuthentication no
# Uncomment if you don't trust ~/.ssh/known_hosts for RhostsRSAAuthentication
#IgnoreUserKnownHosts yes

# To enable empty passwords, change to yes (NOT RECOMMENDED)
PermitEmptyPasswords no

# Change to yes to enable challenge-response passwords (beware issues with
# some PAM modules and threads)
ChallengeResponseAuthentication no

# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication no

# Kerberos options
#KerberosAuthentication no
#KerberosGetAFSToken no
#KerberosOrLocalPasswd yes
#KerberosTicketCleanup yes

# GSSAPI options
#GSSAPIAuthentication no
#GSSAPICleanupCredentials yes

X11Forwarding yes
X11DisplayOffset 10
PrintMotd no
PrintLastLog yes
TCPKeepAlive yes
#UseLogin no

#MaxStartups 10:30:60
#Banner /etc/issue.net

# Allow client to pass locale environment variables
AcceptEnv LANG LC_*

Subsystem sftp /usr/lib/openssh/sftp-server

# Set this to 'yes' to enable PAM authentication, account processing,
# and session processing. If this is enabled, PAM authentication will
# be allowed through the ChallengeResponseAuthentication and
# PasswordAuthentication.  Depending on your PAM configuration,
# PAM authentication via ChallengeResponseAuthentication may bypass
# the setting of "PermitRootLogin without-password".
# If you just want the PAM account and session checks to run without
# PAM authentication, then enable this but set PasswordAuthentication
# and ChallengeResponseAuthentication to 'no'.
UsePAM yes

I've restarted the ssh server but I can still login from another local computer that doesn't have any keys.

What might I be doing wrong?

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  • Latest Post Latest Post by Tinnin

Dani AI

Generated

A short expert note tied to 's follow-up: the most common reason for an unchanged behaviour is simply that the PasswordAuthentication directive remained commented. After changing that setting the daemon must be reloaded — and care must be taken not to lock out remote access.

Useful verification and apply steps:

# syntax check for sshd config
sudo sshd -t

# show effective server configuration (prints post-Match results)
sudo sshd -T | grep -i passwordauthentication

# restart sshd (systemd or older init)
sudo systemctl restart sshd
# or
sudo service ssh restart

Other things that commonly cause password auth to still be allowed:

  • A later Match block or duplicate directive in the file can override the global setting; search the config for additional Match lines.
  • With UsePAM yes, PAM can permit authentication via keyboard‑interactive even when PasswordAuthentication is disabled; confirm ChallengeResponseAuthentication and any PAM rules do not re-enable passwords.
  • Client-side: ensure the SSH client actually offers a key (Windows clients may be using PuTTY/plink, Pageant, or Git-for-Windows OpenSSH — the private key/agent must be in use and key formats must match).
  • Server-side key acceptance and file permissions: the user’s home, .ssh directory and authorized_keys must be owned by the user and restricted (commonly 700 for .ssh, 600 for authorized_keys).

To see what is happening in real time, examine verbose client output and server logs:

# client: see which auth methods are tried
ssh -vvv user@host

# server: watch sshd logs
sudo journalctl -u sshd -f
# or
sudo tail -f /var/log/auth.log

Always keep a working session or console access when disabling password logins so recovery is possible if something is misconfigured. These checks expose why SSH falls back to passwords and prevent accidental lockouts.

Member Avatar for Tinnin

Bollocks! Just saw the commented out part. Easier to see when in colour :)

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