tailieunhanh - Linksys Broadband Routers/Firewalls

Linksys makes a number of broadband routers (with basic firewall functionality) and broadband firewalls | Linksys Broadband Routers Firewalls Linksys makes a number of broadband routers with basic firewall functionality and broadband firewalls with advanced firewall functionality for both wired and wireless networks. Most of the wired products begin with a model number of BEF most of the wireless products begin with a model number of WRT. The Linksys broadband routers firewalls are designed with the home user in mind and therefore are designed with simplicity of implementation in mind. All function as NAT routers and some models and versions also provide stateful packet inspection in addition to NAT unfortunately Linksys does not do a good job of specifying which models and versions of firmware have this functionality. This difficulty is compounded by the fact that SPI was removed from some versions of firmware so literally the same hardware with different versions of firmware may or may not support SPI. This chapter examines the Linksys BEFSR41v4 EtherFast Cable DSL Router with 4-Port Switch. The BEFSR41v4 is designed primarily for the home and small office user and as a result has a relatively basic and simple-to-implement feature set. For ease of review the features have been categorized as follows for the discussion that follows Security and filtering features Routing features Management and administration features Miscellaneous features Security and Filtering Features The BEFSR41v4 is a basic NAT router with firewall functionality that can perform basic port filtering to allow traffic both coming into and going out of the protected network to be filtered. Unlike many firewalls that take a block all permit only minimalist approach to filtering outbound traffic the Linksys is just the opposite instead taking the approach of permit all outbound block only. The idea is that it is easier to block a couple of ports or IP addresses than it is to identify the ports or IP addresses that should be permitted. Inbound traffic still adheres to the minimalist filtering policy .