NAT (ipfw/natd) broken in latest -CURRENT

[Joe Marcus Clarke]

On Thu, 2008-12-18 at 12:53 -0800, Li, Qing wrote:
> Hi Joe,
> 
> I have been trying to recreate your problem but my setup seem to
> work. I then noticed in your original netstat output the p2p
> host route installed by the tunnel interface has the "G" flag
> set. This will certainly cause a routing problem because that
> route is not an indirect route. I modified the kernel code to simulate
> this condition and I do see the error on output, which is expected.
> 
> I assume this problem is consistently reproducible in your setup ?

Absolutely.  Every time I setup the p2p tunnel with the non-proxy ARP
address range.  Traffic flows outbound, but never inbound.  Your
analysis sounds correct.  The kernel doesn't know the interface on which
to encapsulate the return traffic.

Joe

> 
> -- Qing
> 
> 
> > -----Original Message-----
> > From: owner-freebsd-current at freebsd.org [mailto:owner-freebsd-
> > current at freebsd.org] On Behalf Of Joe Marcus Clarke
> > Sent: Tuesday, December 16, 2008 5:20 PM
> > To: current
> > Subject: NAT (ipfw/natd) broken in latest -CURRENT
> > 
> > I just upgraded my i386 -CURRENT box from November 14 to today, and
> now
> > my SSH-over-PPP VPN tunnel no longer works.  I did some packet
> captures,
> > and it appears that NAT is no longer working.  If I send a telnet
> > packet
> > from my client side over the PPP tunnel, I see the SYN go out on the
> > server side network properly translated.  The destination host ACKs
> > correctly, but the ACK never goes back across the tunnel.  It's as if
> > natd is no longer translating the packet on the inbound path.  Besides
> > the upgrade, nothing has changed in my environment.
> > 
> > My ipfw show looks like:
> > 
> > 00050 22974 4677637 divert 8668 ip4 from any to any via em0
> > 00100   194   20696 allow ip from any to any via lo0
> > 00200     0       0 deny ip from any to 127.0.0.0/8
> > 00300     0       0 deny ip from 127.0.0.0/8 to any
> > 65000 24714 4934785 allow ip from any to any
> > 65535     5     396 deny ip from any to any
> > 
> > I am running natd as:
> > 
> > /sbin/natd -s -m -skinny_port 2000 -n em0
> > 
> > The ifconfig for my tunnel interface is:
> > 
> > tun0: flags=8051<UP,POINTOPOINT,RUNNING,MULTICAST> metric 0 mtu 1300
> > 	inet 10.1.1.1 --> 10.1.1.76 netmask 0xffffff00
> > 	inet6 fe80::211:11ff:fe10:461e%tun0 prefixlen 64 scopeid 0x5
> > 	Opened by PID 8018
> > 
> > My netstat on the server side looks like:
> > 
> > Internet:
> > Destination        Gateway            Flags    Refs      Use  Netif
> > Expire
> > default            172.18.254.1       UGS         0    46685    em0
> > 10.1.1.76          link#5             UGH         0     1735   tun0
> > 127.0.0.1          link#3             UH          0     1171    lo0
> > 172.18.254.0/24    link#1             U           0        0    em0
> > 172.18.254.237/32  link#1             U           0        8    em0
> > 
> > The server's uname is:
> > 
> > FreeBSD jclarke-pc.cisco.com 8.0-CURRENT FreeBSD 8.0-CURRENT #130: Tue
> > Dec 16 15:42:09 EST 2008
> > marcus at jclarke-pc.cisco.com:/usr/obj/usr/src/sys/JCLARKE-PC  i386
> > 
> > The previous, working uname was:
> > 
> > FreeBSD 8.0-CURRENT #129: Fri Nov 14 13:51:50 EST 2008
> >     marcus at jclarke-pc.cisco.com:/usr/obj/usr/src/sys/JCLARKE-PC
> > 
> > Joe
> > 
> > --
> > Joe Marcus Clarke
> > FreeBSD GNOME Team      ::      gnome at FreeBSD.org
> > FreeNode / #freebsd-gnome
> > http://www.FreeBSD.org/gnome
> 
-- 
Joe Marcus Clarke
FreeBSD GNOME Team      ::      gnome at FreeBSD.org
FreeNode / #freebsd-gnome
http://www.FreeBSD.org/gnome
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 195 bytes
Desc: This is a digitally signed message part
Url : http://lists.freebsd.org/pipermail/freebsd-current/attachments/20081218/cefed87d/attachment.pgp