RHEL 9 SSH daemon must disable remote X connections for interactive users.
An XCCDF Rule
Description
When X11 forwarding is enabled, there may be additional exposure to the server and client displays if the sshd proxy display is configured to listen on the wildcard address. By default, sshd binds the forwarding server to the loopback address and sets the hostname part of the DISPLAY environment variable to localhost. This prevents remote hosts from connecting to the proxy display.
- ID
- SV-258007r1045073_rule
- Version
- RHEL-09-255155
- Severity
- Medium
- References
- Updated
Remediation Templates
A Manual Procedure
Configure the SSH daemon to not allow X11 forwarding.
Add the following line to "/etc/ssh/sshd_config" or to a file in "/etc/ssh/sshd_config.d", or uncomment the line and set the value to "no":
X11forwarding no