nethserver-openssh

OpenSSH is the premier connectivity tool for remote login with the SSH protocol. It encrypts all traffic to eliminate eavesdropping, connection hijacking, and other attacks. In addition, OpenSSH provides a large suite of secure tunneling capabilities, several authentication methods, and sophisticated configuration options.

The OpenSSH suite consists of the following tools:

  • Remote operations are done using ssh, scp, and sftp.
  • Key management with ssh-add, ssh-keysign, ssh-keyscan, and ssh-keygen.
  • The service side consists of sshd, sftp-server, and ssh-agent.

Properties

the props of the service to configure openssh:

sshd=service
   AllowGroups=group1,group2:sftp,group3
   LoginGraceTime=2m
   MaxAuthTries=6
   PasswordAuthentication=yes
   PermitRootLogin=yes
   Protocol=2
   SubsystemSftp=yes
   TCPPort=22
   UsePAM=yes
   access=green,red
   status=enabled

The prop AllowGroups is used by the service only if the property $sssd{'ShellOverrideStatus'} is enabled.

  • AllowGroups: a comma separated list of group allowed to connect to the sshd service, if the option :sftp is specified then the group is restricted to SFTP
  • SubsystemSftp: (yes|no) enable the sftp service
  • LoginGraceTime: The time after which the server disconnects if the user has not successfully logged in.
  • MaxAuthTries: Specifies the maximum number of authentication attempts permitted per connection. Once the number of failures reaches half this value, additional failures are logged.
  • PasswordAuthentication: (yes,no) Specifies whether password authentication is allowed.
  • PermitRootLogin: (yes,no) Specifies whether root can log in using ssh.
  • TCPPort: Use this TCP port to use sshd
  • UsePAM: (yes,no) Pam can be used to authentify user
  • access: Allow ssh connection to your firewall following different zones.
  • status: (enabled,disabled) Enable or disable the sshd service

Events

Two events takes care to expand and restart the service

nethserver-openssh-update (sshd is restarted) nethserver-openssh-save (sshd is reloaded)

One time password (2FA)

2FA is available only for password authentication. Authentication with public keys will not be affected by 2FA.

The Openssh server can be protected by a Two-factor authentication (2FA). It adds an extra layer of security required to access the new Server Manager. First, users will enter user name and password, then they will be required to provide a temporary verification code generated by an application running on their smartphone.

2FA is disabled by default. Each user can enable it by accessing the Two-factor authentication section under Settings page.