1720 router

[valco]

Hi ! I have one 1720 router. I use this router to connect to internet and i had configured this router as a firewall. I want to know if i can use this router to connect from home to my LAN behind the router , and how to do this.My connection to internet is via ISDN line.

[michael-faust]

Technically it is possible, but there will be some issues. Hopefully, you have configured the firewall to prevent this sort of thing. If so, you will need to make an exception to the rule so that you can get in. Usually this is done by allowing your IP address through. The problem is this. If you are using an ISDN line at home you are probably using a negotiated IP address (one given to you by your ISP). You don't have control over what address you get, and it changes every time you connect, so you don't know what address to let through your firewall. If you can get a static address assigned by your ISP it would be easy.

[valco]

Hi! First of all, thanks for your help. I want to dial-up from home to that router; i have a modem ( normal - not ISDN ) at home which will dial the number of the ISDN line connected to the 1720 router; i will set my home computer with an ip address from the LAN range . All i want is that 1720 router to accept the call and to put me in the office network.

Thanks again !

[michael-faust]

OK That changes my answer slightly. What I said about the firewall issues remains the same, but here are two things that you can look into. An ISDN interface can be set up to accept a call from a non-ISDN host. I think the command is 'isdn not-end-to-end'. I used this one time to connect a 'switch 56' connection to an ISDN. I don't think that it will help you here, because I think that it would prevent ISDN calls. That is something that you would need to look into. As far as setting the IP address to one from the LAN range - that would be a problem. You would be connecting to the ISDN so it would need to be in the same range as the ISDN. This could be another hurdle because the ISP owns the addresses.

The other possible solution is to connect a modem to the router and simply dial in to that. It is a security hole, so be careful.