Port

Port Forwarding Windows

To do that you need to run command prompt as administrator.

Add port forwarding rule.

netsh.exe interface portproxy add v4tov4 listenport=8080 listenaddress=192.168.1.10 connectport=8080 connectaddress=172.16.10.10

Show port forwarding rules.

netsh.exe interface portproxy show all

Delete port forwarding rule.

netsh.exe interface portproxy delete v4tov4 listenport=8080 listenaddress=192.168.1.10

Port Forwarding SSH

ssh -nNT -L 5858:localhost:5757 remotehost

Now request to localhost:5858 will be forwarded to localhost:5757 of the remote machine.

Use -R instead of -L to reverse the direction of the tunnel.

In remote host, request to localhost:5858 will be forwarded to localhost:5757 of the local machine.

Enable 1-1023 ports

1-65535 avaliable ports and in range 1-1023 are the privileged ones.

Give permisstion to run below 1024 port number.

Method 1 - sysctl disable

Directly disable to protect port 1024 below.

sudo sysctl -w net.ipv4.ip_unprivileged_port_start=0

Method 2 - setcap

Setcap to allow port 1024 below to specific program.

sudo setcap 'cap_net_bind_service=+ep' /path/to/program

Method 3 - authbind

First install authbind tool and give permission to ports.

sudo touch /etc/authbind/byport/443
sudo chmod 500 /etc/authbind/byport/443
sudo chown $USER /etc/authbind/byport/443

After that run with authbind, --deep means effect other dependecy program.

authbind --deep myprogram