Topic

Configuring Secure Shell

Applicable to

Non Classified, Official, Protected, Secret, Top Secret

History

Priority

should

Dec 2021

The SSH daemon is configured to: • only listen on the required interfaces (ListenAddress xxx.xxx.xxx.xxx) • have a suitable login banner (Banner x) • have a login authentication timeout of no more than 60 seconds (LoginGraceTime 60) • disable host-based authentication (HostbasedAuthentication no) • disable rhosts-based authentication (IgnoreRhosts yes) • disable the ability to login directly as root (PermitRootLogin no) • disable empty passwords (PermitEmptyPasswords no) • disable connection forwarding (AllowTCPForwarding no) • disable gateway ports (GatewayPorts no) • disable X11 forwarding (X11Forwarding no).

Miscellaneous changes were made to rationale and security controls throughout the publication. This included:

• A review from the Using the Information Security Manual chapter through to the Guidelines for Media chapter.

• Security controls suitable for all audiences have been identified with the ‘All’ applicability marking while additional security controls suitable for just government audiences have been identified with the O, P, S and TS applicability markings.

• Security controls suitable for specific classifications have been amended to include their classification(s) in the wording of the security controls to reduce the reliance on applicability markings to confer suitability.

• Tables in security controls have been converted into prose to allow for inclusion in the SSP annex template and the XML list of security controls.

• The use of ‘official’ and ‘highly classified’ terminology has been replaced with specific classifications to remove ambiguity.

• Security controls relating to high assurance ICT equipment have had their applicability narrowed to ‘S, TS’ reflecting that they are intended for the protection of SECRET and TOP SECRET systems and data.

2015

The settings below should be implemented when using SSH.

2010

The table below outlines the settings that should be implemented when using SSH.

2008

The table below outlines the settings that should be implemented.