2015年1月29日 · PREROUTING: This chain is used to make any routing related decisions before (PRE) sending any packets. Always remember that in PREROUTING/POSTROUTING i.e. NAT table the ACCEPT/DROP/REJECT etc targets of the default FILTER table will not work. The NAT table is only used for taking routing decisions.

2011年6月20日 · PREROUTING (for altering packets as soon as they come in), OUTPUT (for altering locally-generated packets before rout‐ ing), and POSTROUTING (for altering packets as they are about to go out). mangle: This table is used for specialized packet alteration. Until kernel 2.4.17 it had two built-in chains: PREROUTING (for

2016年4月30日 · As the chain names suggest, PREROUTING is done at first when a packet is received and is thus routed based on where it is going (destination). After all other routing rules have been applied, the POSTROUTING chain will determine where it goes based on where it came from (source).

2014年3月28日 · The only instance where NAT affects routing, is when destination NAT is performed in the PREROUTING chain of the "nat" table. Destination NAT affects the destination address, which in turn affects (or at least may affect) how the packet should be routed.

iptables -t nat -N DOCKER-BLOCK iptables -t nat -I PREROUTING -m addrtype --dst-type LOCAL -j RETURN iptables -t nat -I PREROUTING -m addrtype --dst-type LOCAL -j DOCKER-BLOCK That's it! The packet will jump to the DOCKER-BLOCK chain, and if that chain is empty, it'll go out the chain and continue on PREROUTING jumping to RETURN and it'll be ...

2015年11月15日 · It provides the following built-in chains: - PREROUTING (for packets arriving via any network interface) - OUTPUT (for packets generated by local processes) Analysis : So, the RAW table is before conntrack and it was designed with the objective to be used to set the NOTRACK mark on packets that you do not wish to track in netfilter.

2015年3月13日 · 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: I send a packet to a pc in my same local network

2017年11月3日 · @ x-yuri I was also confused about output NAT but finally I got the answer. Prerouting & Postrouting NAT are both for external NAT when some packets are coming to your interface or going out of it and you wanna NAT the address. But OUTPUT NAT is for your local network NAT, I mean when the packets are starting from your application.

2016年12月3日 · I am working on Linux Mint 18.1 and GNU/Linux Debian 9 Stretch (testing). I have only IPv4 available. I would like to increase security on my network, I read this: Block Well-Known TCP Attacks.

2022年9月6日 · I was trying to debug iptables rules of calico and found an weird problem: some packets are lost after nat:PREROUTING. I have three pods on three different nodes, say: edge1/net-tool-edge1: 10.22.4...