[pptp-server] New to PoPToP, routing issues..?

Wed Aug 22 17:17:30 CDT 2001

ERROR.

"All this does is broadcasts the pptp clients IP address against the pptp
servers LAN address"

Sorry that was meant to say :

"All this does is broadcasts the pptp clients IP address against the pptp
servers MAC address"

thanks,
George Vieira
Network Engineer
Citadel Computer Systems P/L
PH +(61)2 9955 2644
FX +(61)2 9955 2659

-----Original Message-----
From: George Vieira 
Sent: Thursday, August 23, 2001 7:56 AM
To: 'eking at tangram.com'; 'Cowles, Steve'; pptp-server at lists.schulte.org
Subject: RE: [pptp-server] New to PoPToP, routing issues..?

Using proxyarp is so the PPTP server accepts packets on behalf of the pptp
client. When a LAN machine pings the pptp client's IP, the pptp server will
relay the ping across, without proxyarp the pptp server ignores the packets
destined to the pptp client.
THIS MUST BE ON THE SAME SUBNET.. proxyarp helps make the pptp client truely
appear to be on the LAN but isn't physically.

All this does is broadcasts the pptp clients IP address against the pptp
servers LAN address. All the local workstations will have an ARP table
saying that to reach the pptp clients IP, send packets to this MAC address
(which really is the pptp server).

Simple solution for you problem, use an IP on the same subnet as your LAN
network...

thanks,
George Vieira
Network Engineer
Citadel Computer Systems P/L
PH +(61)2 9955 2644
FX +(61)2 9955 2659

-----Original Message-----
From: Ed King [mailto:eking at tangram.com]
Sent: Thursday, August 23, 2001 12:28 AM
To: George Vieira; 'Cowles, Steve'; pptp-server at lists.schulte.org
Subject: RE: [pptp-server] New to PoPToP, routing issues..?

So, let me get this straight, on the proxyarp issue, we use 172.16 addresses
on our LAN and use the 192.168 addresses for the PPTP clients and I see the
"can't find ehternet device for proxy arp". What does this message signify?
I am starting to work on getting Network Browsing to work on the clients and
have just started looking at this issue, will this affect Network Browsing?

-----Original Message-----
From: pptp-server-admin at lists.schulte.org
[mailto:pptp-server-admin at lists.schulte.org]On Behalf Of George Vieira
Sent: Tuesday, August 21, 2001 18:38
To: 'Cowles, Steve'; pptp-server at lists.schulte.org
Subject: RE: [pptp-server] New to PoPToP, routing issues..?

You do have a point about the 10 Class A subnet and it's mask but you can't
use proxyarp if the LAN IP is different to the PPTP IP addresses... it'll
say "Can't find ethernet device for proxy arp".

The first 10.19.23.0 is specifying the gateway and the other is just a
network route for it. Some machines do this and others don't it's quite
weird...

thanks,
George Vieira
Network Engineer
Citadel Computer Systems P/L
PH +(61)2 9955 2644
FX +(61)2 9955 2659

-----Original Message-----
From: Cowles, Steve [mailto:Steve at SteveCowles.com]
Sent: Wednesday, August 22, 2001 8:26 AM
To: pptp-server at lists.schulte.org
Subject: RE: [pptp-server] New to PoPToP, routing issues..?

> -----Original Message-----
> From: Chris Storer [mailto:cstorer at infinitisystems.com]
> Sent: Tuesday, August 21, 2001 10:51 AM
> To: Josh Howlett
> Cc: pptp-server at lists.schulte.org
> Subject: RE: [pptp-server] New to PoPToP, routing issues..?
>
>
> Ok.  Just fired up a client, authenticated just fine.  Client received
> 10.19.33.202, with a netmask of 255.0.0.0 - is that strange??

Microsoft assigns the pptp netmask based on the class of network. In your
case the 10.0.0.0 network address is considered a class A which would have a
netmask of 255.0.0.0.

>
> Anyway...Here is from ifconfig for ppp0:
>
> ppp0      Link encap:Point-to-Point Protocol
>           inet addr:10.19.33.200  P-t-P:10.19.33.202
> Mask:255.255.255.255
>           UP POINTOPOINT RUNNING NOARP MULTICAST  MTU:1490  Metric:1
>           RX packets:84 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:31 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:3
>

Looks good...

> Here is routing table:
>
> Kernel IP routing table
> Destination     Gateway         Genmask         Flags Metric
> Ref    Use
> Iface
> 10.19.33.202    *               255.255.255.255 UH    0
> 0        0 ppp0
> 10.19.33.0      *               255.255.255.0   U     0
> 0        0 eth1
> 10.19.23.0      10.19.23.22     255.255.255.0   UG    0
> 0        0 eth0
> 10.19.23.0      *               255.255.255.0   U     0
> 0        0 eth0
> 127.0.0.0       *               255.0.0.0       U     0
> 0        0 lo
> default         10.19.23.1      0.0.0.0         UG    0
> 0        0 eth0
>

Looks OK!! The dual 10.19.23.0 is a little confusing though.

> Here is arp table:
>
> ? (10.19.23.7) at 00:D0:B7:69:2A:81 [ether] on eth0
> ? (10.19.23.1) at 00:02:17:60:D6:4C [ether] on eth0
> ? (10.19.33.202) at * PERM PUP on eth1
>

In your /var/log/messages file... do you see a statement that says something
like "found eth1 for proxy arp" after the local/remote ip assignment???
Without eth1 acting as a proxy arp for your PPTP client, the clients/servers
on your LAN will not be able to communicate with your PPTP client. Just the
PPTP server itself. Also is ip_forwarding enabled?

Steve Cowles

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