Getting to Know Firewall for Network Security

A firewall is an application on a computer system that is used to protect your computer from various attacks from irresponsible parties. A firewall is a way to ensure that personal information or data connection to the internet cannot be accessed by unauthorized parties. If there is attempted access by an unrelated party a firewall will be blocked.

Features in Firewall

Packet filtering

This filtering package is applied by filtering all IP packets going to, passing through or going to that packet. At this stage, the package will be arranged whether it will be forwarded or blocked. This filtering is used to filter packets sent in both directions and the filtering rules are based on the headers on the packet including the sender's IP and destination IP, the protocol used and the port used.

Circuit Level gateway

This firewall works at the transport layer of the TCP / IP model. This firewall monitors TCP handshaking. This Firewall feature can also hide the IP host so that external users cannot see the IP host but the IP of the firewall visible to external users.

Application Level gateway

This firewall feature is often referred to as a proxy firewall, this firewall does not allow packets that come through the firewall directly but applications on the computer running the firewall will continue the request to the services available on the private network. this type of firewall requires prior authentication to enter the network. In addition, this feature also implements auditing and logging as part of the security policy implemented. This type of feature is often implemented on SMTP proxies.

NAT gateway

This feature automatically provides protection against systems that are behind a firewall because NAT Firewall only allows connections that come from computers that are behind a firewall. The purpose of NAT is to multiplex traffic from an internal network and then deliver it to a wider network (MAN, WAN or the Internet) as if the packet came from an IP address or multiple IP addresses.

How Firewall Works

Basically, a firewall is the front line of defense on a computer network to overcome various attacks from outside. The way firewalls work is started by closing ports that are not used because generally, hackers will find loopholes on a network through ports that are left open. The firewall system works by analyzing all data packets that pass through your network, if the packet matches the criteria it will be continued, if there is a suspicious packet it will immediately be blocked. This firewall filtering system is called IDS / IPS. What are IPS and IDS? Will be discussed in the next article. If we analogize easily the firewall is like a security guard in your home that makes sure everything that enters your house has an interest in accordance with the criteria.

Firewall type

Generally, there are 2 types of firewalls based on the location where the firewall works, namely personal firewall and network firewall.

Personal Firewall

A personal firewall is a firewall designed to protect your computer when you are connected to the internet. There are several features on this personal firewall such as protection against viruses, anti-spam, anti-malware, and anti-spyware. Examples of this type of firewall are Linux-based system iptables and Windows Firewall with Advanced Security (WFAS) on Windows-based systems.

Network Firewall

Network Firewall is a firewall that is designed to protect your entire computer network from various attacks, usually, this type of firewall is used by companies. There are 2 forms in this firewall, namely a dedicated device and a device installed on a server. This network firewall also has features that are owned by a personal firewall coupled with several other features, namely circuit-level gateway, application-level gateway, and NAT gateway. Network firewalls generally use routing technology to determine which packets will be allowed or rejected. Examples of this network firewall are Cisco ASA, Checkpoint Firewall, Palo Alto Firewall, etc.