Re: NT and Cornell V1.0 TCP problem

Ian (virus@mad.scientist.com)
Fri, 08 May 1998 23:16:53 -0600


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Your guess was right to assume that I am not an alpha tester for
this new version. I just wasn't aware that non-testers couldn't ask
non-documented questions on a CU list :-) Yes, I have used CU before
(about 1.5 years now). These errors also occured on Cornell version
0.92b2 as well as WP version 3.1.1.xxxxx. WP's are mighty buggier
than Cornell's alpha releases if you ask me...

I am well aware that I have two IP addresses when I dial up to the
Internet. Yes this probably does confuse some software. I just
thought that I might post my question just in case anyone else was
experiencing this problem. I think I have found a fix which is now
working well for me.

It was most definately a "binding order problem". CU was just
grabbing the first IP and adapter it saw in the binding order list.
Since a NIC in Windows NT can have up to 25 IP addresses assigned
per card, there has to be a binding order to these IPs. Five
addresses per card may be configured using Control Panel; however,
more may be added in the Registry. For details, see the IPAddress
registry parameter in online Registry Help. NetBT (NetBIOS over TCP/IP
per RFC 1001/1002) binds to only one IP address per interface card.
When a NetBIOS name registration is sent, it contains the first IP
address in the list of addresses assigned to the NIC. This was the IP
that CU was attaching to. (MS KBASE Q165180, NT Server 4.0 Resource
Kit: Networking Guide)
If you have more than one adapter like a WAN Wrapper (AKA "Dial-up
adapter" in Windows 95) and an ethernet LAN card, there *must* be a
order to which these adapters are bound to their assigned IP
addresses. All I did was change the order in which these *adapters*
were bound. The reason it didn't work the first time was because I
was re-ordering the protocols instead of the adapters. I neglected to
select the "all adapters" pulldown menu located in the upper right of
the control panel network binding window. So, I moved the WAN Wrapper
to the top of the binding order list which seemed to solve the
problem.

I also thought that it might have been the routing table as well. The
routing table gave me a clue that the binding order might be the
problem. When I ran "route print" the ethernet adapter's routing
table showed up first with the WAN Wrapper following.
Since I am running a non-routable IP as defined in RFC 791, turning
on IP routing didn't work. The thing I think is strange (but cool) is
how I am getting the reflector's conference list when CU uses 10.0.0.4
as an IP. This only happens with Cornell's version 0.96a17.

At 11:46 AM 5/9/98 +0800, you wrote:
>i would guess that you are not one of the alpha testers of this new
version.
>have you also used cu-seeme before ? what version ? did you encounter
this
>same problem ?
>
>the problem is the fact that once you dial-in to your ISP, your
machine
>effectively now has two IP addresses --- the one for your LAN and the
one
>assigned to you by your ISP. this confuses cu and probably a lot of
other
>software
>
>i don't believe there is anything like an "IP binding order" --- your
lan
>adapter card needs an ip and your dial-up networking adapter needs an
ip ---
>it's as simple as that. an adapter card can only have one ip address
>associated with it so there isn't any 'binding order'
>
>
>i don't have a lan card with a second ip address installed in my
system but
>i think the problem is in the way the ip routing table gets messed up
after
>you dial-in to your isp. try comparing the output of the 'route
print'
>command before and after you dial-in to your isp. you will probably
need to
>run some batch file after dialing-in to correct the routing table.
you will
>probably need to set it in such a way that ip addresses that belong
to your
>lan network (10.x.x.x) gets routed to your lan network card and
everything
>else gets routed to the ip address assigned by your isp.
unfortunately,
>windows help entry for the 'route' command doesn't give you much info
on how
>to use the utility.
>
>you might also need to turn on 'enable ip forwarding' in the tcp/ip
>settings.
>
>what happens if tcp/ip uses your lan ip address when it sends a
packet out
>to the internet ? well, since the lan ip address is not defined in
any DNS
>or router on the internet, there doesn't seem to be a way for the
return
>packets to find their way back.
>
>
>you might be better of asking yourself the question: "do i really,
really
>need to be connected to tha lan at the same time that i want to
connect to
>the internet ?"
>
>if your answer is no then make two hardware configurations and in one
>configuration, enable the lan adapter and in the other one, disable
it. so
>when you want to connect to the internet, reboot and select the
>configuration with the lan adapter card disabled, this way your lan
ip
>address will not be defined.
>
>

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