Netfilter can by default not track replies to multicast(/broadcast for IPv4) messages. Thus they are, unless they are explicitely allowed through a stateless rule, not matched by a rule using the conntrack match module. To work around this limitation, I developed a equivalent workaround using ipset and iptables. Theoretically the same can be done with …
Category Archives: Netfilter
Getting IRC help: what information do I need to provide?
The necessary information to enable others to help you will of course vary with the problem for which you are seeking help. But here are some minimum guidelines, for users of the #netfilter channel on freenode.net IRC. First off, it’s always a good idea to put a summary of the problem and goal in your …
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A quick run down on iptables rules
What is it? iptables is a cli frontend to netfilter, the Linux kernel firewall/nat implementation for OSI layer 3 and 4.
iptables best practices
Don’t use iptables to apply your rules one at a time, use iptables-restore to apply a whole ruleset in one action. Set your INPUT and FORWARD policy to DROP. Don’t set your OUTPUT policy to DROP unless you really know what you’re doing. If you’re going to implement a blacklist or whitelist, you should look …
Summary page of the Netfilter related resources
Please note that we moved from Freenode to libera.chat because Freenode was taken over by Andrew Lee Summary page of the Netfilter related resources iptables 101 and FAQ to get started quickly iptables tutorial from frozentux flowgraph of the packets in netfilter as svg Managing large lists of IPs,subnets, protocols or ports in iptables using ipset …
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