Server firewall software can be filtering, gateway, or proxy. Filtering uses rules to allow/block access. Gateway types are application-level or circuit-level. Proxies hide IP addresses and use NAT. Antivirus may or may not be included. Different types have different requirements and can be installed on servers or switches.
The types of server firewall software can be divided into three groups: filtering, gateway and proxy software. A firewall can include some or all of these functions. Different types of server firewall software have different requirements in terms of processor speed and memory usage. Because of this, some software is installed directly on the server, and other applications can be installed on a switch or server that acts as a firewall for the network.
Server firewall software filtering works based on administrator-created rules that allow or block access. The filter checks whether or not information has been requested and the contents of packets to see what commands or information they contain. It can also be configured to filter data from specific sources.
When used by itself, a packet filter is not foolproof. It is susceptible to attacks where a proxy may have spoofed the source Internet Protocol (IP) address of the data. Network transmissions from a fake or spoofed IP could allow entry into the network. It can also allow content that is not specifically prohibited by the administrator.
The types of server firewall software gateways are generally divided into application-level and circuit-level classifications. Application Gateway is used where specific types of traffic are monitored. Servers that handle file transfer protocol (FTP) or telephone network applications can use this method. The software can meet the security criteria because the source and type of the data is known.
The circuit-level gateway software works by confirming the destination or source of the data. Monitors the Transmission Control Protocol (TCP) portion of the initial data packets in a session to see if the transfer is authorized. However, it will not check or filter all packets. It is a relatively straightforward and simple approach and allows for minimal use of resources.
The proxy server will intercept all communication entering and leaving a network. It works by hiding or translating the user’s IP address. By changing the IP address of the protected machine, you can protect that machine from external monitoring or attacks. Data packets requested by the device can be allowed while unsolicited packets can be blocked.
Proxies use network address translation (NAT), a protocol in which devices on the user side of the proxy firewall are assigned an IP address starting with 192.168. The server itself may have an externally accessible address if not protected by another server. This anonymity protects your machine from hackers looking for exploitable IP addresses.
Server firewall software may or may not include antivirus definition or operation. Some antivirus security packages may offer firewall protection through filters, but firewall protection is also available on most operating systems and routers.
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