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Date: Sun, 26 Sep 2004 07:42:06 -0700 (PDT)
From: Shu Bin Zhu <shubinzhu@yahoo.com>
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Subject: Running NAT and can't Ping
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I have a strange problem.  Here is my setup.
 
 
ISP 1                    ISP 2
  |                            |
Router 1                Router 2
192.168.0.1           Internet Address A
  |                            |
  |                            |
  ----------------------  Switch --------------------       
  |                            |                        |
FreeBSD1         FreeBSD2               Windows 2000
192.168.0.254   192.168.0.2             192.168.0.253
                        Internet Address B
                        (NAT)
 
The problem is if NAT on FreeBSD2 is not running, all the machines can ping each other.
 
If FreeBSD2 runs NAT, ping still works, except FreeBSD2 can't ping Router1 (192.168.0.1) and FreeBSD1 (192.168.0.254). FreeBSD2 can ping to the interent fine.
 
The Windows 2000 machines gets it's IP from DHCP running on FreeBSD2.  For a day, FreeBSD can't ping Windows 2000 either.  But now it is able to.
 
The NAT configuration on FreeBSD2 is :
 
/sbin/natd -u -a (xxx.xxx.xxx.xxx Internet Address B)
/sbin/ipfw -f flush
/sbin/ipfw add divert natd all from any to any via (xxx.xxx.xxx.xxx Internet Address B)
/sbin/ipfw add pass all from any to any

The unusual setup is the FreeBSD2 only has one ethernet card, and is doing IP aliasing.
 
I have another setup with 2 FreeBSD boxes, and one or both of them are doing NAT, and doesn't have this 'one way' ping problem.
 
Thanks in advance.
 
Shu 
 
 
 
 
 

		
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