Network security administrators sometimes need to be able to abort TCP/IP connections routed over their firewalls on demand. This would allow them to terminate connections such as SSH tunnels or VPNs left in place by employees over night, abort hacker attacks . . . . Network security administrators sometimes need to be able to abort TCP/IP connections routed over their firewalls on demand. This would allow them to terminate connections such as SSH tunnels or VPNs left in place by employees over night, abort hacker attacks when they are detected, stop high bandwidth consuming downloads - etc. There are many potential applications. This article describes how a Linux IPTables based firewall/router can be used to send the right combination of TCP/IP packets to both ends of a connection to cause them to abort the conversation. It describes the steps required to perform this task, and introduces a new open-source utility called "cutter" that automates the process. The use of linux systems as IP network firewalls and routers is becoming increasingly popular. The cheapness of the software and hardware combine with the flexibility and reliability of Linux's networking support to make such a solution highly attractive. It is often possible to deliver routing and fire walling facilities at a fraction of the cost associated with systems provided by industrial heavy-weights such as Cisco, Nortel and others. The link for this article located at ChrisLowth is no longer available. . Sysadmins can now manage TCP/IP sessions on Linux gateways with the new release of Cutter 1.02, enhancing their oversight capabilities.. TCP/IP Management, Firewall Control, Open Source Tools, Network Protection. . Anthony Pell
What is IPFilter? Very simply, a package for permitting (or passing) and denying IP packets based on a range of criteria. It can also provide Network Address Translation (NAT) services, if desired. The IPFilter web site has more details. . . .. What is IPFilter? Very simply, a package for permitting (or passing) and denying IP packets based on a range of criteria. It can also provide Network Address Translation (NAT) services, if desired. The IPFilter web site has more details. The available rules range from quite simple -- for example, deny all traffic on any interface; to relatively complex -- pass and log all ICMP traffic of type ICMP-QUERY from the 199.232.41.24/29 subnet on interface fxp0. Each rule is one-way only, meaning you can block inbound HTTP requests without disrupting outbound requests. When bridging two cards together, OpenBSD's bridge device only checks incoming filter rules. Bidirectional rules are easily created by setting the inbound rules on the other NIC. The link for this article located at Read this full article is no longer available. . What is IPFilter? Very simply, a package for permitting (or passing) and denying IP packets based on. ipfilter, simply, package, permitting, passing), denying, packets, based. . Anthony Pell
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