I'm looking for a way to disable SSH clients from accessing the password prompt as noted here.
I am unable to disable the password:
prompt for root login. I have change the sshd_config
file to read:
ChallengeResponseAuthentication no
PasswordAuthentication no
UsePAM no
and have also changed the permissions chmod 700 ~/.ssh
and chmod 600 ~/.ssh/authorized_keys
. What am I missing? Does this require I have a passphrase?
Verbose dump:
debug1: Authentications that can continue: publickey,password
debug1: Next authentication method: publickey
debug1: Offering RSA public key: /home/user/.ssh/id_rsa
debug1: Authentications that can continue: publickey,password
debug1: Trying private key: /home/user/.ssh/id_dsa
debug1: Trying private key: /home/user/.ssh/id_ecdsa
debug1: Next authentication method: password
# 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
#Privilege Separation is turned on for security
UsePrivilegeSeparation yes
# Lifetime and size of ephemeral version 1 server key
KeyRegenerationInterval 3600
ServerKeyBits 768
# Logging
SyslogFacility AUTH
LogLevel INFO
# Authentication:
LoginGraceTime 120
PermitRootLogin no
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 no
In file /etc/ssh/sshd_config
# Change to no to disable tunnelled clear text passwords
#PasswordAuthentication no
Uncomment the second line, and, if needed, change yes to no.
Then run
service ssh restart
I followed these steps (for Mac).
In /etc/ssh/sshd_config
change
#ChallengeResponseAuthentication yes
#PasswordAuthentication yes
to
ChallengeResponseAuthentication no
PasswordAuthentication no
Now generate the RSA key:
ssh-keygen -t rsa -P '' -f ~/.ssh/id_rsa
(For me an RSA key worked. A DSA key did not work.)
A private key will be generated in ~/.ssh/id_rsa
along with ~/.ssh/id_rsa.pub
(public key).
Now move to the .ssh folder: cd ~/.ssh
Enter rm -rf authorized_keys
(sometimes multiple keys lead to an error).
Enter vi authorized_keys
Enter :wq
to save this empty file
Enter cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
Restart the SSH:
sudo launchctl stop com.openssh.sshd
sudo launchctl start com.openssh.sshd
Here's a script to do this automatically
# Only allow key based logins
sed -n 'H;${x;s/\#PasswordAuthentication yes/PasswordAuthentication no/;p;}' /etc/ssh/sshd_config > tmp_sshd_config
cat tmp_sshd_config > /etc/ssh/sshd_config
rm tmp_sshd_config
The one-liner to disable SSH password authentication:
sed -i 's/PasswordAuthentication yes/PasswordAuthentication no/g' /etc/ssh/sshd_config && service ssh restart
Run
service ssh restart
instead of
/etc/init.d/ssh restart
This might work.
Source: Stackoverflow.com