Date: Fri, 10 Jul 2015 00:19:46 +0000 From: bugzilla-noreply@freebsd.org To: freebsd-doc@FreeBSD.org Subject: [Bug 201448] [IPFW] keep-state and in-kernel NAT exposes local ip on external interface Message-ID: <bug-201448-9@https.bugs.freebsd.org/bugzilla/>
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https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=201448 Bug ID: 201448 Summary: [IPFW] keep-state and in-kernel NAT exposes local ip on external interface Product: Documentation Version: Latest Hardware: amd64 OS: Any Status: New Severity: Affects Only Me Priority: --- Component: Documentation Assignee: freebsd-doc@FreeBSD.org Reporter: g_amanakis@yahoo.com According to the example of the handbook regarding NAT (https://www.freebsd.org/doc/handbook/firewalls-ipfw.html), the inbound NAT rule should be placed first (below 0400) followed by the outbound NAT rule (below 24000) -------8<-------- ipfw nat 123 config ip xxx.xxx.xxx.xxx same_ports reset 00100 reass ip from any to any in 00200 allow ip from any to any via lo0 00300 allow ip from any to any via em1 00400 nat 123 ip from any to any in recv em0 00500 check-state 00600 skipto 24000 ip from any to me dst-port 80,443,22,500,4500,1194,993,8112 in recv em0 keep-state 00700 skipto 24000 ip from any to any out xmit em0 keep-state 00800 deny log ip from any to any 24000 nat 123 ip from any to any out xmit em0 24100 allow ip from any to any -------8<-------- However this allows some packets to escape NAT (why?) and IPs on the LAN (behind NAT) are exposed on the external interface (where NAT is performed). When one places the NAT rules with the opposite order (i.e. outbound rule first and then the inbound rule) the problem disappears. -------8<-------- ipfw nat 123 config ip xxx.xxx.xxx.xxx same_ports reset 00100 reass ip from any to any in 00200 allow ip from any to any via lo0 00300 allow ip from any to any via em1 00400 nat 123 ip from any to any out xmit em0 00500 check-state 00600 skipto 24000 ip from any to me dst-port 80,443,22,500,4500,1194,993,8112 in recv em0 keep-state 00700 skipto 24000 ip from any to any out xmit em0 keep-state 00800 deny log ip from any to any 24000 nat 123 ip from any to any in recv em0 24100 allow ip from any to any -------8<-------- See https://forums.freebsd.org/threads/ipfw-keep-state-and-in-kernel-nat-exposes-local-ip-on-external-interface.52134/ -- You are receiving this mail because: You are the assignee for the bug.
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