how to "join" LAN with plip link?

Hello. I have successfully connected two computers through plip0 (don't
know if current speed of 3kB/s is reasonable). The 'server' has a parallel
port and is connected to LAN, the 'client' have a parallel port and is
not connected to LAN, I guess this is typical. Now how can I make
this 'client' join the LAN?

For client to access LAN I need to set up nat on the 'server', this is
rather straigthforward. However for the client to 'join' the LAN it needs
to have a unique IP address on the lan and is accessible by other hosts on
the LAN through this IP address.

One method is used by Windows 2000: when a 'client' 'dial' to the 'server'
(no dialing actually happened, Windows 2000 calls it a dialup connection
anyway), this client is given an IP address that the 'server' requested
for the client from the DHCP server. Let's say server IP address is
192.168.1.12 and client IP address is 192.168.1.13. To the client, there
is only one parallelport dialup connection, local side is 192.168.1.13,
server side is 192.168.1.12, no ARP or other ethernet technology is
involved. To other hosts on the LAN, 192.168.1.13 is a real
host existing in the LAN, it has its mac address which is the same MAC
address of 192.168.1.12. Other hosts on the LAN think 'server' has two IP
addresses. So the server automatically forward any traffic to
192.168.1.13 to its client. The whole process is transparent, we don't
know how internally Windows 2000 did the job.

Can this method be used on Linux through alternative configuration? I mean
can we configure a Linux host to act almost the same way as described
above?

Maybe for Linux there is an alternative method: 0) we configure 'server'
to run NAT, 1) 'server' request two IP addresses, 192.168.1.12 for its own
use and 192.168.1.13 is set as the out-going interface of NAT; 2) we set
plip link of server to be 10.0.0.1, plip link of client to be 10.0.0.2; 3)
we set NAT default host (sometimes called DMZ) to be 10.0.0.2. The result
is similar as Windows 2000: if someone access 192.168.1.13 from LAN,
traffic is forwarded to 10.0.0.2 which is the 'client'.

I can also think of the 3rd method: set up VPN server on the 'server',
client dial in to server after plip link is created, then the 'server' can
grant a LAN ip address to client as VPN usually do. I guess this solution
is too complicated.

So what would you suggest / recommend? I know this issue is perhaps not
worth solving because we do have NIC everywhere, I am purely interested to
find out a solution.

On 25 Dec 2006, in the Usenet newsgroup comp.os.linux.networking, in article
<(E-Mail Removed)>, Zhang Weiwu wrote:

>Hello. I have successfully connected two computers through plip0 (don't
>know if current speed of 3kB/s is reasonable).

-rw-rw-r-- 1 gferg ldp 46049 Apr 26 2001 PLIP

That's a mini-howto, and section 1 states:

The speed achieved depends completely on your hardware (CPU and
parallel port) and system load, in general it may be from 5 Kb/sec up
to even 40 Kb/sec.

but you may also want to have a look at the "Linux Network Administrator's
Guide" (nag2 at any LDP mirror, or http://tldp.org/guides.html). It has a
whole chapter on PLIP.

>The 'server' has a parallel port and is connected to LAN, the 'client'
>have a parallel port and is not connected to LAN, I guess this is typical.
>Now how can I make this 'client' join the LAN?

The nag2 should help. Either you need to configure the "server" as a router,
and have all systems know to send packets to the router as a gateway to the
LAN (or client), or you need to configure the server to do 'proxy-ARP'. In
the first method, the 'client' and LAN hosts would be on different networks
(such as 192.168.1.0/24 for the LAN, and 192.168.2.0/24 for the client),
while the proxy-ARP method would require client and LAN to be on the same
network range. See also

-rw-rw-r-- 1 gferg ldp 19372 Aug 28 2000 Proxy-ARP-Subnet

another mini-howto.

>For client to access LAN I need to set up nat on the 'server',

Not really - proxy-ARP is much simpler.

>Can this method be used on Linux through alternative configuration? I mean
>can we configure a Linux host to act almost the same way as described
>above?

You're making it much more complicated than necessary, but in essence you
are talking of proxy-ARP. Please remember that a "young" as Linux is, it
was doing IP networking long before microsoft invented computers, or what
ever they claim to have done. IP actually goes back to 1981, when microsoft
was yet to discover the concept of 'directories' in MS-DOS 1.1.

>So what would you suggest / recommend? I know this issue is perhaps not
>worth solving because we do have NIC everywhere, I am purely interested to
>find out a solution.

PLIP is obviously not going to be as fast as Ethernet, but this is an
alternative that will work. I don't bother using DHCP, because my
systems remain on the same network all of the time, and it's easy to
use a static setup.

Old guy