53aa78eada0ff51cdff536156444c4ad846cba56
howto/networksettings.md
| ... | ... | @@ -32,4 +32,13 @@ Check that ALL your vpn interfaces allow ip forwarding for ipv6/ipv4. |
| 32 | 32 | $ sysctl -a | grep forwarding |
| 33 | 33 | ``` |
| 34 | 34 | |
| 35 | +### Note on firewalls, conntrack and asymmetric routing |
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| 36 | + |
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| 37 | +Do not configure iptables/nftables to drop packets with invalid conntrack state in forward chain. |
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| 38 | + |
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| 39 | +In some cases your router will not see traffic from both sides e.g. requests are sent via different path not including your networks |
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| 40 | +but responses are fowarded via your network. This will prevent conntrack from assigning any meaningful state information to these packets |
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| 41 | +and your firewall will drop it if it is configured to drop packets with invalid state. |
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| 42 | + |
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| 43 | + |
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| 35 | 44 | Happy Routing! |
| ... | ... | \ No newline at end of file |