Re: IP Forwarding to Windows machine
Bob Proulx a écrit :
> Mike McClain wrote:
>> ______________ ________________
>> | Debian | LAN | Windows 2000 |
>> --------Inet----| Linux |-----------------| S40 |
>> (ppp) | 192.168.1.2 | cross-over | 192.168.1.3 |
>> |_____________| |_______________|
>
> It isn't 100% clear so I will ask. What IP address is the Debian box
> getting on the ppp connection? You only list one IP address for it
> but of course it must have another one for the upstream connection.
Not necessarily. The PPP interface may have the same address as the
Ethernet interface, or even be left unnumbered (without an address) and
use the address of the other interface.
Example here of same address on eth0 (to LAN) and ppp0 (to ISP) :
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast
state UNKNOWN qlen 1000
inet6 2001:7a8:6d23:1::1/64 scope global
valid_lft forever preferred_lft forever
15: ppp0: <POINTOPOINT,MULTICAST,NOARP,UP,LOWER_UP> mtu 1460 qdisc
pfifo_fast state UNKNOWN qlen 3
link/ppp
inet6 2001:7a8:6d23:1::1/128 scope global
I used to leave ppp0 unnumbered and it happily used the address of eth0,
until I added a 6to4 tunnel interface and ppp0 started to use the local
tunnel address instead, which I didn't want.
> And you left that one out leaving us guessing about it.
Anyway, it does not matter so much. If ping to the outside works, then
IP connectivity, addressing and routing are correct.
> Hopefully it isn't getting another 192.168.1.x IP address there from
> its upstream. If so then that would create routing problems for it.
> It would have the 192.168.1 subnet on both ports and that would cause
> it problems.
Not necessarily.
> For simple operation a router needs different IP subnets
> on the different ethernet ports.
A PPP link is not an Ethernet link. It does not have a subnet. At most
just a pair of arbitrary addresses at each end.
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