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New Member

Forward web, mail, etc. DHCP? Newbie!

Hello one and all,

Please excuse me while I first say that I am a 100% Cisco NEWBIE. I will soon be starting my very first Cisco classes and eventually will be taking over VoIP for my company. But this is a way's off. In order to start my new path, I bought two 2924 model switches and a 2611 router for my personal use at home. These will be learning tools for me, however, there are a few things I'd like initial help with because I already have a fully-functional, linux-based network at my home, complete with every type of server known to man.

Now as I said, I'm a total newbie, and truth be told, I haven't even turned this router on yet! I know almost no Cisco commands. But I am knowledgable in networking as a whole, and know linux CLI well. So I do have a clue, but please feel free to explain things to me like a 5 year old regardless.

I have Apache web server running on my current linux box. I also have Sendmail as my mail server. Now right now that same linux box is actually acting as my network router via NAT and is connected directly to my cable modem.

So...

Item 1: Since my ISP sends out DHCP addresses, will this be problematic with the 2611? Right now, when I get a new address (about twice a year), I don't have to do anything expect change my DNS settings with my registrar to point to the new IP. I can't think of why that would change, but will it?

Item 2: Eth0 on my linux box gets the DHCP address from my ISP and then eth1 (which is static) sends DHCP addresses to my LAN. For intitial configuration (until I learn enough to REALLY do it right), can someone please just tell me how to accomplish this on the 2611? OR... Should I not do this and leave my secondary server as a DHCP server instead of having the 2611 do it?

Item 3: Can someone please tell me how to take certain addresses out of the range so my static devices (switches, servers, my UPS, etc) won't be in the range?

Item 4: Since my current server/router is also my web server, people who go to www.mydomain.com simply get there. But once the server is behind the 2611, obviously, they won't get to my website unless I forward port 80 to the internal IP address of the server. Right? How do I do this?

Item 5: And can someone please answer the same question, but in regards to e-mail?

Thank you in advance for any help. It will be greatly appreciated. I just want to make sure I can get a basic working configuration before I start my classes. That way, I'll have as minimal personal network downtime (important since e-mail for my entire family is run by me) as possible.

Thank you,

Chris

  • Other Network Infrastructure Subjects
3 REPLIES

Re: Forward web, mail, etc. DHCP? Newbie!

Item 1: Since my ISP sends out DHCP addresses, will this be problematic with the 2611? Right now, when I get a new address (about twice a year), I don't have to do anything expect change my DNS settings with my registrar to point to the new IP. I can't think of why that would change, but will it?

>>> 2611 should not have a problem, there are IOS that will support where the ethernet interface will get an IP address from the ISP's DHCP. The interface's configuration will like the following:

interface Ethernet1

ip address dhcp

ip nat outside

notice the ip nat outside, this will be the interface facing the ISP and teh router will be doing the NAT from your internal network to the public Internet.

Item 2: Eth0 on my linux box gets the DHCP address from my ISP and then eth1 (which is static) sends DHCP addresses to my LAN. For intitial configuration (until I learn enough to REALLY do it right), can someone please just tell me how to accomplish this on the 2611? OR... Should I not do this and leave my secondary server as a DHCP server instead of having the 2611 do it?

>> 2611 can also act as a DHCP server, or you can leave the current DHCP server to serve out IP addresses for your internal networks.

Item 3: Can someone please tell me how to take certain addresses out of the range so my static devices (switches, servers, my UPS, etc) won't be in the range?

>>> do you mean take is out of the DHCP server's scope of addresses served out? For the router it will look like this:

ip dhcp excluded-address 192.168.1.1 192.168.1.99

From your current DHCP server you shoudl already know how to take out certain addresses out of scope.

Item 4: Since my current server/router is also my web server, people who go to www.mydomain.com simply get there. But once the server is behind the 2611, obviously, they won't get to my website unless I forward port 80 to the internal IP address of the server. Right? How do I do this?

>> If the current web server will now have a private ip address, that will need to be translated as follows:

ip nat inside source static tcp 192.168.1.99 80 interface Ethernet1 80

The example above is under the assumption that the web server have an internal ip address 192.168.1.99. with that you can probably figure out what the rest of the commands do..

Item 5: And can someone please answer the same question, but in regards to e-mail?

>> same as above, but you need to figure out which port number the email server uses for SMTP. And if it's a different server altogether then the ip address will also be that email server's ip address.

This should have addressed all your questions. Please rate if the posts helped.

New Member

Re: Forward web, mail, etc. DHCP? Newbie!

Hi bosolaza!

I appreciated ur great explanation!

10xs

New Member

Re: Forward web, mail, etc. DHCP? Newbie!

Bosalaza,

I will attempt everything you suggested and pray nothing catches fire! I greatly appreciate your excellent advice and will post back with questions (should I have any) or further comments.

Thank you very much!

Chris

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