ssh-permit-empty-passwords-no

This module ensures that PermitEmptyPasswords is set to no.

Maintainer

Nick Anderson

Module stats

Total Downloads: 356
Updated: Dec 23, 2021

Installation version

Version
Released on May 11, 2022

Tags

Installation

                    
cfbs add ssh-permit-empty-passwords-no
Description
Dependencies
Comments

Disallowing remote shell access to accounts that have an empty password reduces the probability of unauthorized access to the system.

If possible it is recommended to inhibit the use of passwords at all and instead realy on keys with

PasswordAuthentication no

but inhibiting login with empty passwords is an excellent fallback and good to have present in case a situation prevents the use of keys.

Examples

Add PermitEmptyPasswords yes to /etc/ssh/sshd_config.

$ grep ^PermitEmpty /etc/ssh/sshd_config
PermitEmptyPasswords yes
$ sudo cf-agent -KIb ssh_permit_empty_passwords_no
    info: Using command line specified bundlesequence
    info: Copied file '/etc/ssh/sshd_config' to '/etc/ssh/sshd_config.staged.cfnew' (mode '600')
    info: Removed old backup '/etc/ssh/sshd_config.staged.cfsaved'
    info: Backed up '/etc/ssh/sshd_config.staged' as '/etc/ssh/sshd_config.staged.cfsaved'
    info: Moved '/etc/ssh/sshd_config.staged.cfnew' to '/etc/ssh/sshd_config.staged'
    info: Updated '/etc/ssh/sshd_config.staged' from source '/etc/ssh/sshd_config' on 'localhost'
    info: Replaced pattern '^\s*(PermitEmptyPasswords\s+(?!no$).*|PermitEmptyPasswords)$' in '/etc/ssh/sshd_config.staged'
    info: replace_patterns promise '^\s*(PermitEmptyPasswords\s+(?!no$).*|PermitEmptyPasswords)$' repaired
    info: Edited file '/etc/ssh/sshd_config.staged'
    info: Copied file '/etc/ssh/sshd_config.staged' to '/etc/ssh/sshd_config.cfnew' (mode '640')
    info: Removed old backup '/etc/ssh/sshd_config.cfsaved'
    info: Backed up '/etc/ssh/sshd_config' as '/etc/ssh/sshd_config.cfsaved'
    info: Moved '/etc/ssh/sshd_config.cfnew' to '/etc/ssh/sshd_config'
    info: Updated '/etc/ssh/sshd_config' from source '/etc/ssh/sshd_config.staged' on 'localhost'
    info: Executing 'no timeout' ... '/bin/systemctl --no-ask-password --global --system -q restart sshd'
    info: Completed execution of '/bin/systemctl --no-ask-password --global --system -q restart sshd'
$ grep ^PermitEmpty /etc/ssh/sshd_config
PermitEmptyPasswords no

The reason that there is quite a bit of output is because it's a multi-step process:

  • Backup the config

  • Edit the config

  • Replace old config with new config

  • Restart SSH daemon

If you run cf-agent -KI again, there will be no output, no changes will be made, since the configuration is already correct.

How it works

This module ensures that PermitEmptyPasswords is set to no in /etc/ssh/sshd_config leveraging lib_sshd_config:global_key_values from the library-sshd-config module.

Dependencies

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