Ensure SSH Protocol is set to 2

MediumLevel 1Automatedlinux

Description

SSH supports two different and incompatible protocols: SSH1 and SSH2. SSH1 was the original protocol and was subject to security issues. SSH2 is more advanced and secure.

How it is checked

Audit method: Shell command

shell

alt0() { command -v grep >/dev/null 2>&1 || { echo "step1: grep not installed"; return 1; }; command -v sshd >/dev/null 2>&1 || { echo "step1: sshd not installed"; return 1; }; o=$(bash -c 'sshd -T | grep protocol' 2>&1); printf '%s\n' "$o" | tr -s ' \t' '  ' | sed 's/^ //;s/ $//' | grep -Fxq -- 'Protocol 2' || { echo step1: missing 'Protocol 2'; return 1; }; }; if alt0; then echo compliant; fi

Expected output: compliant

How it is fixed

Fix method: Guidance or infrastructure patch

Edit the /etc/ssh/sshd_config file to set the parameter as follows: Protocol 2 Restart sshd : systemctl restart sshd

Properties

Operating systems: alinux-2
Tags: cis-convertedlinux
Reference: CIS Aliyun Linux 2 Benchmark v1.0.0 ARCHIVE - 5.2.2

Check this host

Run this on a machine you are allowed to audit. The scan is read-only.

shell

tmaegis scan --target linux