tailieunhanh - Firewalls Packet Filtering

Sits between two networks Used to protect one from the other Places a bottleneck between the networks All communications must pass through the bottleneck – this gives us a single point of Filtering Rejects TCP/IP packets from unauthorized hosts and/or connection attempts bt unauthorized hosts Network Address Translation (NAT) Translates the addresses of internal hosts so as to hide them from the outside world Also known as IP masquerading Proxy Services Makes high level application level connections to external hosts on behalf of internal hosts to completely break the network connection between internal and external hosts . | Firewalls CS-455 Dick Steflik Firewalls Sits between two networks Used to protect one from the other Places a bottleneck between the networks All communications must pass through the bottleneck – this gives us a single point of control Protection Methods Packet Filtering Rejects TCP/IP packets from unauthorized hosts and/or connection attempts bt unauthorized hosts Network Address Translation (NAT) Translates the addresses of internal hosts so as to hide them from the outside world Also known as IP masquerading Proxy Services Makes high level application level connections to external hosts on behalf of internal hosts to completely break the network connection between internal and external hosts Other common Firewall Services Encrypted Authentication Allows users on the external network to authenticate to the Firewall to gain access to the private network Virtual Private Networking Establishes a secure connection between two private networks over a public network This allows the use of the Internet as a connection medium rather than the use of an expensive leased line Additional services sometimes provided Virus Scanning Searches incoming data streams for virus signatures so theey may be blocked Done by subscription to stay current McAfee / Norton Content Filtering Allows the blocking of internal users from certain types of content. Usually an add-on to a proxy server Usually a separate subscription service as it is too hard and time consuming to keep current Packet Filters Compare network and transport protocols to a database of rules and then forward only the packets that meet the criteria of the rules Implemented in routers and sometimes in the TCP/IP stacks of workstation machines in a router a filter prevents suspicious packets from reaching your network in a TCP/IP stack it prevents that specific machine from responding to suspicious traffic should only be used in addition to a filtered router not instead of a filtered router Limitations of Packet Filters IP . | Firewalls CS-455 Dick Steflik Firewalls Sits between two networks Used to protect one from the other Places a bottleneck between the networks All communications must pass through the bottleneck – this gives us a single point of control Protection Methods Packet Filtering Rejects TCP/IP packets from unauthorized hosts and/or connection attempts bt unauthorized hosts Network Address Translation (NAT) Translates the addresses of internal hosts so as to hide them from the outside world Also known as IP masquerading Proxy Services Makes high level application level connections to external hosts on behalf of internal hosts to completely break the network connection between internal and external hosts Other common Firewall Services Encrypted Authentication Allows users on the external network to authenticate to the Firewall to gain access to the private network Virtual Private Networking Establishes a secure connection between two private networks over a public network This allows the use of