6/15/2023 0 Comments Iptables![]() Packets enter this chain just before handing them off to the hardware.Įach rule in a chain contains the specification of which packets it matches. Packets sent from the machine itself will be visiting this chain. ![]() Local delivery is controlled by the “local-delivery” routing table: ip route show table local.) FORWARDĪll packets that have been routed and were not for local delivery will traverse this chain. (N.B.: It does not have anything to do with processes having a socket open. Packets will enter this chain before a routing decision is made. These chains have no policy if a packet reaches the end of the chain it is returned to the chain which called it. The system administrator can create as many other chains as desired. Predefined chains have a policy, for example DROP, which is applied to the packet if it reaches the end of the chain. There are five predefined chains (mapping to the five available Netfilter hooks), though a table may not have all chains. ![]() The origin of the packet determines which chain it traverses initially. Packets start at a given box and will flow along a certain path, depending on the circumstances. the point that was jumped from is remembered.) Every network packet arriving at or leaving from the computer traverses at least one chain. ![]() A rule in a chain can cause a goto or jump to another chain, and this can be repeated to whatever level of nesting is desired. Packets are processed by sequentially traversing the rules in chains. Each table is associated with a different kind of packet processing. Xtables allows the system administrator to define tables containing chains of rules for the treatment of packets. ![]()
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