In the age of digital communication, a router plays quite a significant role. With the ever-increasing need for a digital network, these routing devices are upgraded every other day. For real, a diverse range of routers is specifically architectured to cater to targeted user demands.
But what is prevalent among these is IPtables for a Linux model. This tool helps a router with rule configuration. IPtables Port Forwarding can easily be used to increase your network’s connectivity.
But wait, You have never heard about it before? Don’t worry. This guide will walk you through all you need to know to understand Port Forwarding using IPtables. But first –
What is an IP table?
The Linux kernel’s framework, Netfilter, is responsible for network-related operations. The framework is fundamental for network operations, from network address translation to packet filtering to port translation and more. It essentially divides what goes in and out.
Netfilter offers the essential infrastructure for IP tables. Thus the IPtables utility is a tool that provides an interface for the Netfilter framework. Thus the Netfilter, with the help of IPtables, provides a mechanism to configure packet filtration rules.
How do IPtables work, and why should you use it
Considering a data packet, IPtables provide a broader perspective. The utility functions by comparing traffic against defined rules. There is so much the IPtables utility has to offer. IPtables allow more flexibility to be introduced regarding network operations. Thus you are not restricted to mere rejection and acceptance of data packets.
Further, it also acts as a perfect interface and an efficient tool kit to complete your networking tasks. With the help of IPtables, an administrator can easily filter out traffic for their network.
What does NAT have to do with Port Forwarding
NAT stands for network address translation, which is essential for Port Forwarding and networks in general. It maps from local addresses to public ones and thus sits between the network that connects your LAN to the world beyond. Port Forwarding is essentially an application of NAT.
What is Port Forwarding?
In simple words, Port Forwarding is a technique using which you can easily allow external sources to access a device on your LAN. The idea is also known as Port Mapping.
At its core, the concept is that services are mapped to specific ports. These ports, once forwarded, can provide an easy way for data to be channeled into the network without getting blocked. Hence, Port Forwarding allows a user to create a freeway for transferring data by modifying the destination of a relevant packet.
Why is Port Forwarding even necessary?
Well, it most certainly is. All routers offer firewall utility that protects a system against any malicious threat. It does the job by monitoring and blocking traffic whenever it is deemed inappropriate. Often it so happens when data packets arrive from sources that are unknown to the router or network.
Thus the firewall is responsible for tracking who is allowed to communicate with external servers and services and those who aren’t. So to prevent specific access requests from getting blocked by the firewall, you need to utilize IPtables Port Forwarding.
Steps for Port Forwarding using IPtables
If the destination and source are part of different subnets: First, you will have to enable IP Forwarding using the following commands:
- sysctl net.ipv4.conf.eth0.forwarding=1
- sysctl net.ipv6.conf.eth0.forwarding=1
Now for IPtables Port Forwarding, you need to define rules for IPtables for a particular TCP port. You can write the destination IP address for the data packet using the command:
- iptables -A PREROUTING -t nat -p tcp -i ppp0 –dport 8001 -j DNAT –to-destination 192.168.1.200:8080
Similarly, the source IP address of the gateway can be written with the following command:
- iptables -A POSTROUTING -t nat -p TCP -d 192.168.1.200 –dport 8080 -j MASQUERADE
You can direct traffic towards the destination address using:
- iptables -A FORWARD -p TCP -d 192.168.1.200 –dport 8080 -m state –state NEW,ESTABLISHED,R
To send requests to the same network: However, if Port Forwarding IPtables are configured to send requests to the same network, the scenario is slightly different.
- iptables -t nat -A PREROUTING -p tcp –dport 80 -j DNAT –to-destination 192.168.1.200:8080
But is Port Forwarding even safe?
The answer depends upon the state of your system’s security. Port Forwarding will be a big no if you do not have proper security mechanisms and software running in your system. This means your network can easily be intercepted. That is because Port Forwarding generally opens up holes in a router’s firewall. That can not be well paired with an already insecure system.
Hence, to avoid a malicious attack, you need to make sure you have proper security set up for your network. A reliable VPN service can do the job for you. With a VPN, you can hide your identity and encrypt your channel. These measures ensure that your system and network’s security isn’t compromised.
Want to learn more about Port Forwarding? Check out our blog for various games and routers.
