MASQD over PPP, but with 2 Valid IP's

Posted on 1998-01-29
Medium Priority
Last Modified: 2010-03-18

I would like to set up a linux box with 2 valid ip's. the 1st ip would be for a network, and the 2nd would be routed to a Linux or NT Box( over a network card. Can this be done? Will Routing the 2nd ip to the linux/nt box conflict with the network?

here is a diagram:

            | ISP   |
      ISDN      []
            [](ppp0 with a valide class C IP)
      |Linux  Box  |
MASQ NIC  []      [] 2nd NIC With a valid Class C (eth1)      []
            |Linux or NT Masqd box|(

is this possible?


Question by:screen
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions

Accepted Solution

sauron earned 300 total points
ID: 1587457
Yes, it's possible. I'm not clear on exactly what you want from your post, but you can set this sort of thing up. You can have a Linux box, with 2 NIC's, and for example give them and as addresses. You set the subnet mask for both to, and you can route between the two cards by simply enabling routing in the kernel. Then, you can add a ppp device, and use a valid class C from your ISP on this.

You then compile masquerading support into the kernel, and you use the firewalling rules to specify the masquerade policy, so you can specify that packets from the network are masqueraded, but packets from the network are not, or are blocked, or whatever you like.

This is all set up using ipfwadm rules. You'd probably also want dial on demand support, recent versions of pppd support this, but you might also want to look into diald, which can be found at


though it seems to be down at the moment.


Author Comment

ID: 1587458
yea But What about 2 valide class C's? What i need is 2 webservers (port 80), each on their 192.168.x.0 network. The Router would route(or in this case port forward) the 1st ip to, and the 2nd ip to

now ppp0 has 1 ip(in this case an ISDN line), howdo i "mount" the 2nd IP.

I think i can use IPFWADM to control which MASQD packet's goes to.


Featured Post

The Orion Papers

Are you interested in becoming an AWS Certified Solutions Architect?

Discover a new interactive way of training for the exam.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

I have seen several blogs and forum entries elsewhere state that because NTFS volumes do not support linux ownership or permissions, they cannot be used for anonymous ftp upload through the vsftpd program.   IT can be done and here's how to get i…
Note: for this to work properly you need to use a Cross-Over network cable. 1. Connect both servers S1 and S2 on the second network slots respectively. Note that you can use the 1st slots but usually these would be occupied by the Service Provide…
If you're a developer or IT admin, you’re probably tasked with managing multiple websites, servers, applications, and levels of security on a daily basis. While this can be extremely time consuming, it can also be frustrating when systems aren't wor…
Have you created a query with information for a calendar? ... and then, abra-cadabra, the calendar is done?! I am going to show you how to make that happen. Visualize your data!  ... really see it To use the code to create a calendar from a q…

719 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question