The following rules are provisioned by weave-npc:
-A WEAVE-NPC-EGRESS -m state --state RELATED,ESTABLISHED -j RETURN
-A WEAVE-NPC-EGRESS -m set ! --match-set weave-local-pods src -j RETURN
-A WEAVE-NPC-EGRESS -d 224.0.0.0/4 -j RETURN
-A WEAVE-NPC-EGRESS -m state --state NEW -j WEAVE-NPC-EGRESS-DEFAULT
-A WEAVE-NPC-EGRESS -m state --state NEW -m mark ! --mark 0x40000/0x40000 -j WEAVE-NPC-EGRESS-CUSTOM
-A WEAVE-NPC-EGRESS -m state --state NEW -m mark ! --mark 0x40000/0x40000 -j NFLOG --nflog-group 86
-A WEAVE-NPC-EGRESS -m mark ! --mark 0x40000/0x40000 -j DROP
-A WEAVE-NPC-EGRESS-CUSTOM <rulespec> -j MARK --set-xmark 0x40000/0x40000
-A WEAVE-NPC-EGRESS-CUSTOM <rulespec> -j RETURN
-A WEAVE-NPC-EGRESS-DEFAULT <rulespec> -j MARK --set-xmark 0x40000/0x40000
-A WEAVE-NPC-EGRESS-DEFAULT <rulespec> -j RETURN
For each rule we create two (mark and return). We cannot just accept
a packet if it matches any rule, as a packet might need to traverse
the ingress npc as well which happens later in the chain (in some cases
we cannot detect whether packet is ingress or egress, so we need to
check both chains).
Bryan Boreham