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Re: TO the holier-than-thou guru



On Thu, 6 Mar 1997 tomk@westgac3.dragon.com wrote:

> I'm happy that we have "experts" on this list to help us out of our
> ignorance. I've looked at the documentation of a Cisco and agree that
> configuring it runs a close second to my least favorite activity
> (going to the dentist).

configuring ciscos is fairly easy, i've found. took me a few hours the
first time i had to set one up, now it only takes me about an half an
hour. cisco's aren't particularly difficult: IP is difficult until you
get to know it (like unix is difficult until you get to know it and then
it makes perfect sense :-)

what's near the top of my list of least favourite activities is debugging
broken Win3 systems with conflicting DLLs (e.g. trumpet & chameleon
winsock installed on the same system) without having the option of taking
the easy way out (blowing the whole system away and starting from
scratch).   With Win you're hunting in the dark - it's usually impossible
to get at the information you need to find out what's going wrong...at
least with unix there are log files.

> > Remember, unless one has a dedicated link, your IP address will be
> > provided by the ISP following a successful login (most ISP recycle
> > IP addresses). You must specify "noipdefault" and "defaultroute
> > in /etc/ppp/options. If you set a DEFAULT GATEWAY and ROUTE in
> > /etc/init.d/network, unset it.
>
> Good info, thanks! Now let me ask a specific question, my ISP not only
> dynamically allocates the IP address for it's users, but dynamically
> allocates the server IP (several PPP servers on a rotating incoming
> line). Question: how do you configure PPP to handle this situation?

this is a fairly common situation - many isps have multiple dialin boxes.

The trick is that there is no trick...you don't do anything special. You
use the 'noipdefault' option as mentioned above and refrain from listing
*any* IP addresses in /etc/ppp/options or on the pppd command line.
You let the remote server tell you both *your* IP address and *its* IP
address.

if you really wanted to, you could use the ipcp-accept-local and
ipcp-accept-remote options but they arent needed unless you've decided
to ignore what was said above about not listing *any* IP addresses in the
options file or on the command line.

from the pppd man page:

       ipcp-accept-local
              With this option, pppd will accept the peer's  idea
              of  our  local  IP  address,  even  if the local IP
              address was specified in an option.

       ipcp-accept-remote
              With this option, pppd will accept the peer's  idea
              of  its  (remote) IP address, even if the remote IP
              address was specified in an option.

        .
        .
        .

       noipdefault
              Disables the default behaviour  when  no  local  IP
              address  is  specified,  which  is to determine (if
              possible) the local IP address from  the  hostname.
              With  this option, the peer will have to supply the
              local IP address during IPCP negotiation (unless it
              specified  explicitly  on the command line or in an
              options file).



if you haven't already done so, print out the pppd man page - it's very
readable (for a man page).  pppd is one of the best documented programs
around - clear, straightforward man page and lots of howtos and readme
files (in /usr/doc/HOWTO and /usr/doc/ppp, of course).


if you have ghostscript installed and working, or a postscript printer,
then "man pppd | enscript -2r -G" makes a nice 2 pages on 1 sheet
printout

craig


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