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Summary: Connecting a LAN to the Internet Through Dial-Up PPP
Summary: Connecting a LAN to the Internet Through Dial-Up PPP
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The original question was sent to two mailing lists:
linux-il@linux.org.il
solaris-x86@webpro.eis.com
I got many questions; If you were the sender of one of them and your
name
isn't mentioned below, please excuse me...
> Hi!
>
> I don't know if this is the correct place for this question, but I am sure
> that someone here will know the answer.
>
> I have a Solaris (on a notebook) connected to the Internet through a PPP
> dial-up modem. It has a dynamic IP that is given temporarily by the ISP.
> I have another machine with Win'95, connected to the Solaris by Ethernet
> (cross 10BaseT). I want the Win to access the Internet:
> _____ _______ _________ _______
> | | | | | | cross | |
> | ISP |----(phone-line)----| modem |----| Solaris |----X----| Win95 |
> |_____| |_______| |_________| 10BaseT |_______|
BTW, I know I can add a computer to be a router or something similar,
but it is not my intention, so thanks to the people who advised to
use additional machine with OS/2 and/or Linux and/or Novell etc., but
I'm not sure that these solutions are for me. When I'll have a direct
connection, it will be done through Linux router/firewall, but now I
want my Solaris notebook to be the "PPP-gateway".
> Now comes a bunch of questions:
>
> 1. What IPs should I give the machines? 10.*? None?
Yes, 10.* (e.g. 10.0.2.?) is OK, and so 192.168.10.?, although almost
any other IP is OK (Ariel Nowersztern <reln@cs.huji.ac.il>, Alex
Shnitman
<alexsh@usa.net>, Ira Abramov <ira@scso.com>, Reginald Carey
<rbcarey@jgvandyke.com> ). It is recommended to use "1" or "254" for the
gateway, but there is no real reason. I use 10.0.2.254 for the Solaris,
10.0.2.2 for the Win95, and 10.0.2.3 for the Linux. My netmask is
255.255.255.0, so any IP suffix in the range 1-254 is OK.
> 2. What network components should be installed on the Win?
It is simpler than it seemed before... Just installing both interfaces
(TCP/IP+Ethernet LAN, and PPP Dial-Up) the same way as installing them
separately (PPP because this machine sometimes access the dial-up
directly). When trying to access the Internet, the dialog box of the
dial-up is popped up automatically, and if you want to access the net
through the gateway, just cancel it!
Of course, the driver of the Ethernet card must be installed, and
TCP/IP,
and the private IP of the machine, and the IP of the DNS, and the IP of
the gateway (which is the Solaris in this specific case). When
configuring
the dial-up, don't give a private IP, but tell the system to take its
IP from the ISP.
(Thanks to Ariel Nowersztern <reln@cs.huji.ac.il>, Ira Abramov
<ira@scso.com>, Alex Shnitman <alexsh@usa.net> ).
> 3. Should an address translation be installed on the Solaris? How?
Thanks to all the people who mentioned IP masquarading, unfortunately
Solaris does not support it. I found somewhere at my home an old
package from SunSoft that I got in a promo, called "Internet Gateway for
Solaris", which does the work. In addition, there is an excellent public
domain solution, called "IP filter" (
http://www.cyber.com.au/users/darrenr/ )
(thanks to Jefferson Ogata <ogata@pmpro.com> ). Jefferson and Viktorie
Navratilova <vnavrat@orion.it.luc.edu> mentioned another public domain
solution, "SLiRP". Of course, there are many expensive products, such
as most of the firewalls, that do the work.
> 4. Can Proxy (on the Solaris) solve my problem? Will it allow programs
> to contact external servers (e.g. Java applets that communicate with
> external servers)?
As you all answered, the normal protocols (HTTP etc.) are solved by a
proxy (I don't remember why I asked this question, after all, the answer
is so obvious...).
Regarding to the Java applets: as I was afraid, they use their own
protocols and their own ports, so nothing can be done using a simple
proxy (of course, address translation is a different story). Someone
asked about an example: the Hebrew chat (supported by my Hebrew Netscape
for UNIX!) of http://www.walla.co.il/online/chat/ uses port 4444.
An interesting point: My Internet Explorer (under Win95) can access the
Internet through my Apache proxy (under Solaris), but can not access the
Apache itself (even without a proxy), although Netscape (under Solaris)
can access it. I'm really not an Apache novice... Very strange...
> 5. Let's assume that everything was solved. Can I still tell the Win to
> call the ISP explicitly (for example, when the notebook is not there)?
> How? Automatically (by recognizing that the Solaris/gateway is not
> there) or manually?
As I already said (answer for question #2), it is simpler than it seemed
before. Look at that answer again. The point is that Win95 allows you
dynamically to decide if you want to dial your ISP (by selecting
"Connect"
in the dial-up dialog box) or to access the Internet through your
gateway
(by selecting "Cancel").
Regarding to the proxy settings: although a script can be written for
turning it on/off (thanks Ira), the simplest solution is to set it
manually each time you change the method.
Reginald Carey <rbcarey@jgvandyke.com> tells that he has a static IP
from his ISP. I agree that this is the best case; unfortunately, my
main ISP ( http://www.netvision.net.il ) wants $250 per month (!!!)
for a static IP (they call it "Multi-Call PPP"). This price can buy
a frame-relay connection in some ISPs, including all the needed static
IPs...
Thanks again to all the people that their answers helped to produce this
summary!
Eli Marmor
El-Mar Software Ltd.
marmor@elmar.co.il