o ye of little faith...
On Wed, 21 Jun 2000, kevin lyda wrote:
> i am of the opinion that no packet can come in on the public interface
> and either get received by the private address or go out on the private
> network. paul disagrees.
[paulj at rossi paulj]$ telnet gateway-private
Connected to gateway-private.itg.ie.
Escape character is '^]'.
Last login: Wed Jun 21 14:40:50 from xxxx
[mylogin at gateway]$
logout and look at arp cache on my laptop:
[paulj at rossi paulj]$ arp
Address HWtype HWaddress Flags Mask Iface
gateway ether 00:08:C7:F3:2A:47 C eth0
gateway-private ether 00:08:C7:F3:2A:47 C eth0
hey look... the public interface on our server is claiming to be both
gateway and gateway-private!!! (if you believe ifconfig then
gateway-private should at least have a different MAC addr).
Moral of the story:
there is no connection between IP addresses and interfaces in
linux (2.2+). Absolutely none......
if you think there is then you have been sucked in by ifconfig. (use 'ip'
instead for a view more consistent with how linux actually works). All the
IP's that are local to a linux box are accessible from /any/ interface.
(unless you setup INPUT rules with ipchains to prune out packets according
IP's are not bound to interfaces in any way....
also, in this setup, packets would go across from public to private (if
ip_forward was enabled). I can't demonstrate with telnet because the
routing means there will be no replies going back - but that doesn't
matter too much for UDP app's.
> which is it?
kev, you know i'm right.. :)
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