[pptp-server] Newbie question

[Gord Belsey]

RE: Question A.

The local ip directive is used as the local ip addr of the ppp connection, just as remoteip is for the remote's end of the ppp connection.  I use a range for both remoteip and localip on my PoPToP server.  As clients make connections, the local and remote IP addrs for the PPP connection are taken from this range.  If you look at ifconfig with a PPTP connection up, you'll see the local and remote )\(P-t-P) addresses taken from their respective range.  With a Linux client,  the localip/remoteip on the PoPToP server is ignored (as I understand it) if you supply the desired IP addresses in the (Linux PPTP client)  command line  with ipcp-accept-local and ipcp-accept-remote in the PPP options file.  I'm not sure if this option exists for WIN clients.

Hope this is useful info :o)

Gord Belsey
  ----- Original Message ----- 
  From: Jose Miguel Varet 
  To: pptp-server at lists.schulte.org 
  Sent: Tuesday, February 29, 2000 9:07 AM
  Subject: [pptp-server] Newbie question


  Hello all,

  I'm fairly new to PopTop/VPNs, and I must say that I've found the VPN technical concept to be a fascinating one. Right now I'm finishing a PopTop installation on a linuxbox which has a permanent connection via cablemodem, trying to emulate the pptd posibilities of a Win2000 server; that includes the ability to assign local IP addresses to incoming clients from a specific range. In fact, my case is a simple one, with no masq'ing/firewalling issues :



      Private Subnet   <------>             Eth0                Eth1                <-------->              PPTP Client
     192.168.1.2-128                 192.168.1.1        212.79.128.150                           xxx.yyy.www.zzz
                                                  ------------------------------------------          --------------------------------------------
                                                         LINUXBOX / PopTop                            Internet


  Althought this is a very simple configuration, I've got some newbie/dumb questions about this story... perhaps some of you would find five minutes to drop me a few lines about them :

  a) IP assignment to remote clients : AFAIK, this is controlled via the "remoteip" directive in /etc/pptpd.conf. In my config example, this would be "remoteip 192.168.1.129-150" to allow a maximum of 21 concurrent incoming clients. 'till now, allright. But, what in the heavens is the "localip" directive used for ? Specifing the local interface in which poptop is listening for the incoming pptp connections? (if so, this would be eth1, 212.79.128.150) or perhaps the interface which is gonna be used for talking to the private subnet ? (in this case, 192.168.1.2).  Sorry, but I cannot figure out what this directive means. And what's more arcane for me :-) , what does a "localip" diretive with a range do? ("localip a.b.c.1-20", for example).

  b) Netbios broadcasts not travelling down a ppp link : Ok, we all knew that netbios is a non-routable protocol, so this is no surprise... instead of installing a samba as a master domain controller, there's a "real" NT server inside the private subnet (192.168.1.2). Could I log onto that machine in order to take advantage of its WINS server and shares ?

  c) For the last one, the $1M question (at least for me... I've found no info about this anywhere). While netbios broadcasts won't travel down... will TCP/IP broadcasts travel "up" from my pptp client to the private subnet ? The best example I can think of is some of those network-oriented deathmatch games, like Quake. When you look for game servers, the game client issues a tcp/ip broadcast to the local subnet. All servers which receive such a broadcast will answer to the client, so it knows what copmuters are hosting a game. Let's suppose I want to find a game server from my pptp client. Will a server placed in, let's say, 192.168.1.30, "listen" that broadcast, and thus reply to my client ?

  Yes, you'll think these are rather dumb questions, but hey, I'm new to this... take mercy at me :-)
  Many thanks in advance,


                  Jose Miguel Varet
                  System Administrator - Tech. Dept.
                  ATT, Sevilla
      
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