[GnomeMeeting-list] NAT Problem over VPN

[Randall Smith <randall tnr cc>]

I'm trying to use GM over an SSH-PPP VPN.  The configuration is as follows.

                                                   PC3(Win2K - NM)
PC1(Debian - GM) <-VPN-> PC2(Debian) <--> LAN <-->
                                                   PC4(RHL72 - GM)
PC1:
    eth0:  192.168.1.8
    ppp0:  192.168.3.2
    route add -net 10.7.0.0 netmask 255.255.0.0 dev ppp0
    GM 1.02
    GM Settings: Enable IP Translation checked.
    Public IP of NAT/PAT router:  10.7.74.145 (Not really public?)
    Enable Video Transmission
    Enable Video Reception

PC2:
    eth0:  10.7.74.145
    ppp0:  192.168.3.1
    iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE

PC3:
    eth0:  10.7.74.132
    NM 3.01
    instcodec.exe installed
    NM Settings: Automatically Receive Video at the
    Start of Each Call

PC4
    eth0:  10.7.74.141
    GM Settings:


1. PC1 can ping PC3 and make TCP connections such as ssh.
2. PC3 CANNOT connect to PC1 because I don't know how to alter the 
routing tables on Win2K and wouldn't be suprised if I couldn't.

PC1(GM) calls PC3(NM).  PC3 answers and the call is connected.  Video 
does NOT show on PC3 (I don't know about audio), but video option in 
toolbar ungrays.  No video or audio on PC1.  Ethreal shows that TCP 
traffic is OK and UDP from PC1 -> PC3 is OK, but UDP from PC3 -> PC1 is 
sent to 192.168.3.2 which PC3 CANNOT RESOLVE!  PC3 should send its UDP 
packets through 10.7.74.145, but it appears that that NAT option in GM 
is not working (probably b/c its not a public IP).  So how can I make 
this work.  Also, why does PC3 not show video from PC1 when I can see 
the UDP traffic arriving?

PC1 calls PC4.  PC4 answers.  PC4 shows video.  PC4 has no video or 
sound card (just used to test) and sends no udp packets out.

If you can figure this out and you live in New Orleans, I'll buy you 
lunch :)

Randall