What Roles Do Firewalls & Proxy Servers Play in Network Security?by Micah McDunnigan
Network security involves addressing threats both from outside the network and from within. This involves keeping hackers from probing or attacking a network over the Internet, and keeping infected computers from using their position on the network to let threats bypass external security. Firewalls and proxy servers play a number of roles in limiting access and refusing connections that could compromise network security.
Firewalls for External Defense
Firewalls are devices that take data requests and evaluate them against a specific set of rules. Depending on if the request violates one of the rules a network administrator has programmed into the firewall, the device will either allow a request to proceed or reject the request. The right set of rules can keep hackers from scouting or attacking your network infrastructure by rejecting their incoming connections before they ever reach your router.
Firewalls for Internal Security Threats
Firewalls can work to protect networks even if threats have initially made their way onto the network. Firewalls apply their rules to incoming and outgoing traffic. This allows them to stop viruses that have already infected computers on the network from sending data off the network. This could be data such as the network's structure or authentication data from key loggers that malware is trying to send back to the hacker that deployed the malware. By blocking such outgoing transmissions, firewalls can keep malware that managed to infect computers on the network from passing sensitive information back to hackers.
Reverse Proxy Servers
Proxy servers play a role in protecting networks from public-facing threats. Reverse proxy servers are configured to accept incoming requests for data, establish the legitimacy of the request, then retrieve any legitimate requests from the servers behind them. After retrieving the data, the proxy forwards the data to the machine that initiated the request. By placing a level of protection between the public and servers, reverse proxies keep hackers from trying to use public-facing Web interfaces to try gain unauthorized access to the servers the proxies protect.
Forward Proxy Servers
Proxy servers configured as forward proxies can work with firewalls to add an extra level of protection against threats from within a network. Positioned between the machines on a network and a firewall, a forward proxy can add an extra level of scrutiny to outgoing data requests. The forward proxy can reject any suspicious or dangerous requests before forwarding them to the firewall, decreasing the likelihood that the network will allow any connections that could compromise the network's security.
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