# Cis Ubuntu1604 V200 5 3 23

> Ensure SSH MaxSessions is limited

- Skill: `cyberstrikeus/cis-ubuntu1604-v200-5-3-23` (Agent Skill)
- Install (CLI): `npx skillmds@latest add cyberstrikeus/cis-ubuntu1604-v200-5-3-23`
- Raw SKILL.md: https://api.skillmd.com/api/skills/cyberstrikeus/cis-ubuntu1604-v200-5-3-23/raw
- Safety review: PASS (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: cyberstrikeus (https://skillmd.com/u/cyberstrikeus)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/cyberstrikeus/cis-ubuntu1604-v200-5-3-23

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# CIS Ubuntu Linux 16.04 LTS Benchmark v2.0.0 - Control 5.3.23

## Description

The `MaxSessions` parameter Specifies the maximum number of open sessions permitted per network connection.

## Rationale

To protect a system from denial of service due to a large number of concurrent sessions, use the rate limiting function of MaxSessions to protect availability of sshd logins and prevent overwhelming the daemon.

## Audit Procedure

### Command Line

Run the following command and verify that output `MaxSessions` is `10` or less:

```bash
sshd -T -C user=root -C host="$(hostname)" -C addr="$(grep $(hostname) /etc/hosts | awk '{print $1}')" | grep -i maxsessions
```

### Expected Result

```
maxsessions 10
```

Run the following command and verify the output:

```bash
grep -Ei '^\s*MaxSessions\s+(1[1-9]|[2-9][0-9]|[1-9][0-9][0-9]+)' /etc/ssh/sshd_config
```

Nothing should be returned.

## Remediation

### Command Line

Edit the `/etc/ssh/sshd_config` file to set the parameter as follows:

```
MaxSessions 10
```

## Default Value

MaxSessions 10

## References

1. SSHD_CONFIG(5)

## CIS Controls

Version 7

5.1 Establish Secure Configurations - Maintain documented, standard security configuration standards for all authorized operating systems and software.

## Profile Applicability

- Level 1 - Server
- Level 1 - Workstation

## Assessment Status

Automated