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The ESXi host Secure Shell (SSH) daemon must not permit tunnels.


Finding ID Version Rule ID IA Controls Severity
V-256393 ESXI-70-000025 SV-256393r885960_rule Medium
OpenSSH has the ability to create network tunnels (layer 2 and layer 3) over an SSH connection. This function can provide similar convenience to a virtual private network (VPN) with the similar risk of providing a path to circumvent firewalls and network Access Control Lists (ACLs).
VMware vSphere 7.0 ESXi Security Technical Implementation Guide 2023-06-21


Check Text ( C-60068r885958_chk )
From an ESXi shell, run the following command:

# /usr/lib/vmware/openssh/bin/sshd -T|grep permittunnel

Expected result:

permittunnel no

If the output does not match the expected result, this is a finding.
Fix Text (F-60011r885959_fix)
From an ESXi shell, add or correct the following line in "/etc/ssh/sshd_config":

PermitTunnel no