Re: [Openvpn-users] OpenVPN and Proxy-ARP

[Joern K. <sou...@sm...>]

On Wed, 12 Oct 2005, /dev/rob0 wrote:

Hallo,

[long essay about linux ARP-Handling]
Well I also never noticed this arp-problem with Linux, but in Windows
it is a "feature" or innovation ;-). You first have to enable proxy
arp, before Windows use it, here a few Windows Screenshots:

(I "killed" the Screenshots, they are too long filled up with no
information at all, so please just trust me:)

Directly after my VPN-Client(192.6.1.229) has connected to the
VPN-Server(192.6.1.230, LAN-IP:192.6.1.10)

VPN-Client: "ping 192.6.1.18" <- An IP on the LAN-Interface
---Not working!
VPN-Server: ("fwparp 192.6.1.229 192.6.1.10") Turn on Proxy-ARP
VPN-Client: "ping 192.6.1.18" <- An IP on the LAN-Interface
---Working

So, believe me: You have to enabled something, it isn't working like
on linux.

LAN-MAC-Address of VPN-Server: 00-13-D4-64-14-32
VPN-Client-MAC-Address:        00-FF-33-6F-FD-AE


Now I disabled Proxy-ARP again and tried your solution.
New connect to the VPN-Server:
VPN-Server:arp -s 192.6.1.229 00-13-D4-64-14-32
--Not working
VPN-Server:arp -d 192.6.1.229
VPN-Server:arp -s 192.6.1.229 00-FF-33-6F-FD-AE
--Not working
VPN-Server:arp -d 192.6.1.229

(I looked it up Windows added this arp Entrys on the LAN-Interface.)

An ARP-Table is for the PC itself, only linux is
automaticaly distributing its local ARP-Table and so does
proxy-arping. In Windows you have to enable it, so please don't look
in Linux-Manuals something up that isn't working with Windows.

... As you have noticed I don't like manuals maybe because I have no
Windows-Manuals, maybe because I just trust my eyes...

If you like to: Take a Windows PC and test it all of what I have send
you in this mails. But the point ist proxy-arp in Linux is an
automatic feature and in Windows it ist nearly not existing.

> Bottom line here: each of us thinks the other is misunderstanding ARP
> and proxy ARP. NBD. Perhaps one or both of us will come away from this
> with greater understanding. I think I did/will/am. :) "man 7 arp" has
> some interesting parts pertaining to this.
Do you now know the difference between a local ARP-Table and the
special linux feature of "knowing" when to use proxy-arp automaticaly
out of his arp-table and that this is a linux-feature not implemented
in Windows?

I whould love it if I am wrong. And if you find an easier way of
solving this arp-proxy problem for me. But I have no solution.

Ciao, Joern.