Date: Sun, 11 May 2014 11:14:37 GMT From: Andriy Mayevskyy <major12@gmail.com> To: freebsd-gnats-submit@FreeBSD.org Subject: kern/189655: [ipfw] ipfw does not pass same_ports option to kernel nat (libalias) Message-ID: <201405111114.s4BBEbnk093936@cgiserv.freebsd.org> Resent-Message-ID: <201405111120.s4BBK0eH033772@freefall.freebsd.org>
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>Number: 189655 >Category: kern >Synopsis: [ipfw] ipfw does not pass same_ports option to kernel nat (libalias) >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Sun May 11 11:20:00 UTC 2014 >Closed-Date: >Last-Modified: >Originator: Andriy Mayevskyy >Release: 9.2-RELEASE >Organization: >Environment: FreeBSD natbox 9.2-RELEASE FreeBSD 9.2-RELEASE #0: Mon Apr 21 17:32:51 EEST 2014 root@natbox:/usr/obj/usr/src/sys/TEST i386 >Description: ipfw command is used to configure kernel nat. ipfw option 'same_ports' seems to be ignored while configuration and kernel nat (libalias) always behaves like this option was enabled. E.g. If we send packet from 10.0.0.5 port 200 with same_ports packed should be aliased (if possible) to <alias_addr>:200 and w/o same_ports to <alias_addr>:<random_port> Currently packets are aliased to port 200 in both cases ipfw nat 1 config if em1 same_ports and ipfw nat 1 config if em1 >How-To-Repeat: Test kernel is: ------------- ident TEST options IPFIREWALL options IPFIREWALL_DEFAULT_TO_ACCEPT options IPDIVERT options LIBALIAS options IPFIREWALL_NAT include GENERIC ------------- ipfw is configured in next way: ipfw nat 1 config if em1 ipfw add 100 nat 1 ip from any to any via em1 Network layout is client --(em0) natbox (em1)-- internet At client I use python script to bind to port 200 and send packets to internet. At natbox I can check packets with tcpdump -n -i em1 >Fix: I suppose that there is a bug in sys/netpfil/ipfw/ip_fw_nat.c LibAliasSetMode has next prototype /* Change mode for some operations */ unsigned int LibAliasSetMode( struct libalias *la, unsigned int flags, /* Which state to bring flags to */ unsigned int mask /* Mask of which flags to affect (use 0 to * do a probe for flag values) */ ) and it is called in wrong way LibAliasSetMode(ptr->lib, cfg->mode, cfg->mode); This code will set only the bits that are 1 (ones). But we need to clear bit that is responsible for SAME_PORTS so this bit value should be 0 in mode and 1 in mask. So since same_ports are enable by default in libalias and ipfw fails to change it we have described incorrect behavior. >Release-Note: >Audit-Trail: >Unformatted:
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