2015年1月29日 · I am trying to understand how this system works and I have problems to understand the difference between using NAT PREROUTING or filter FORWARD. From what I understand, the PREROUTE can send the packet to another server, avoiding the filter. If NAT can handle this via PREROUTE, what is the purpose of having a FORWARD rule in the filter?

2011年6月20日 · Hello people. I'm learning about IPTables, but I don't fully understand the chains of the NAT table (PREROUTING, POSTROUTING and OUTPUT). I'm

2016年4月30日 · For example, on my server, incoming ports that are to be forwarded (NATed) are all defined in the PREROUTING chain as DNAT, and all packets that come from the NATed interfaces, go through the POSTROUTING chain as SNAT, and consequently (in this case), go through the filter FORWARD chain.

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The filter table is best place to drop packets, agreed. But, out of the box, Docker bypasses INPUT filter rules with PREROUTING to its own FORWARD rules making Docker containers world-accessible.

2015年3月13日 · I know linux has 3 built-in tables and each of them has its own chains as follow: FILTER: PREROUTING, FORWARD, POSTROUTING NAT: PREROUTING, INPUT, OUTPUT, POSTROUTING MANGLE: PREROUTING, INPUT, FORWARD, OUTPUT, POSTROUTING But I can't understand how they are traversed, in which order, if there is. For example, how are they traversed when:

2019年11月21日 · I am trying to send a UDP on a packet to two different external/remote IPs using iptables. Currently I am running a command that looks like this: iptables -t nat -A PREROUTING -i eth0 -p udp --dp...

2020年5月31日 · I am trying to do dnat using iptables like below iptables -t nat -A PREROUTING -i eth0 -p tcp --dport 9000 -j DNAT --to-destination 10.0.0.1:9000 Is it possible to mention output interface also using iptables or routing table is the only way?

2015年11月15日 · iptables --table raw --append PREROUTING --in-interface lo --jump ACCEPT the packets are handled sooner, without the need to go though conntrack+mangle+nat+routing.

iptables -t nat -A PREROUTING -p tcp --dport port -j DNAT --to-destination server B:80 However, this simple rule does not work. We must add the following rule: iptables -t nat -A POSTROUTING -j MASQUERADE Why so? Why do we need to add a POSTROUTING rule? After the PREROUTING, the packet must go automatically to server B right?