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

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-258764	SRG-OS-000480-VMM-002000	ESXI-80-000209	SV-258764r933353_rule	2023-10-11	1

Description
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).

ℹ️ Check
From an ESXi shell, run the following command: # esxcli system ssh server config list -k permittunnel or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $esxcli.system.ssh.server.config.list.invoke() \| Where-Object {$_.Key -eq 'permittunnel'} Example result: permittunnel no If "permittunnel" is not configured to "no", this is a finding.

ℹ️ Check

From an ESXi shell, run the following command: # esxcli system ssh server config list -k permittunnel or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $esxcli.system.ssh.server.config.list.invoke() | Where-Object {$_.Key -eq 'permittunnel'} Example result: permittunnel no If "permittunnel" is not configured to "no", this is a finding.

✔️ Fix
From an ESXi shell, run the following command: # esxcli system ssh server config set -k permittunnel -v no or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $arguments = $esxcli.system.ssh.server.config.set.CreateArgs() $arguments.keyword = 'permittunnel' $arguments.value = 'no' $esxcli.system.ssh.server.config.set.Invoke($arguments)

✔️ Fix

From an ESXi shell, run the following command: # esxcli system ssh server config set -k permittunnel -v no or From a PowerCLI command prompt while connected to the ESXi host, run the following commands: $esxcli = Get-EsxCli -v2 $arguments = $esxcli.system.ssh.server.config.set.CreateArgs() $arguments.keyword = 'permittunnel' $arguments.value = 'no' $esxcli.system.ssh.server.config.set.Invoke($arguments)