topic Re: IS a Dynamic IP address possible for Redhat 7.1 mail server in Operating System - Linux

IS a Dynamic IP address possible for Redhat 7.1 mail server

R Inserro — Fri, 26 Apr 2002 18:01:57 GMT

I'm trying to configure Redhat 7.1 to act as a mail server with sendmail. I understand most of the configuration issues, but the /etc/hosts
files needs my server ipaddress followed by any and all domain names it services.

The problem is that a dynamic ip address.
I have an acccount with dyndns.org that updates
my domain to their dns repointing database.
this works for my ftp server just fine.

In setting up sendmail, however, can I enter in my domain name www.gnomecentral.com in place of the ip address? will send mail resolve my domain name to the correct ip address for my server? or is there another way to do this.

Re: IS a Dynamic IP address possible for Redhat 7.1 mail server

Mark Fenton — Sat, 27 Apr 2002 00:30:19 GMT

The short answer is yes.

I don't think sendmail needs to know what its own ip is, and will happily process any mails it gets from anywhere it can resolve via DNS. The real challenge is keeping dynamic DNS updated with your proper MX record so that email senders will be able to forward to you.

Happy emailing!
Mark

Re: IS a Dynamic IP address possible for Redhat 7.1 mail server

R Inserro — Sat, 27 Apr 2002 00:36:47 GMT

What is a "proper MX record"
do i really need one?
i have the domain gnomecentral.com
I have set up a host called smtp.gnomecentral.com to handle mail.
Would "smtp.gnomecentral.com" be a valid MX record if I truly need one?

Re: IS a Dynamic IP address possible for Redhat 7.1 mail server

Msquared — Mon, 29 Apr 2002 06:42:19 GMT

"proper mx record" refers to the MX record in the zone for which you are accepting mail. For example, if you are foo.com, you might have something like this:

foo.com. IN MX 10 mail.foo.com.

The problem is that mail.foo.com (your RH7.1 box) has a dynamic IP, so you need to make sure that it is updated whenever your IP changes. From the top of my head, there's something in the ipup scripts that you can use to trigger something when your IP changes. You'll have to add a script to update your DNS...

Re: IS a Dynamic IP address possible for Redhat 7.1 mail server

Mark Fenton — Tue, 30 Apr 2002 00:39:55 GMT

This link summarizes the challenges of hosting internet services when you have a dynamic address.

http://www.tldp.org/HOWTO/PPP-HOWTO/dynamic-server.html

To overcome these limitations (say you have a domainname to which you want others to be able to forward your mail) you'll need to do something like this:

http://www.dyndns.org
http://www.openknowledge.org/acs/dynamic-ip.html
http://www.davidsimmons.com/tips/081797/
http://dns2go.deerfield.com/

I don't think it's possible (really) to run a DNS server that would report your address to other computers on the internet via a dynamic connection.

Best of luck!
Mark

Re: IS a Dynamic IP address possible for Redhat 7.1 mail server

Msquared — Tue, 30 Apr 2002 01:43:05 GMT

Woo, Mark's second reply reminded me of this:

http://www.changeip.com/

They even have a script that you can run at ifup that will notify them of your new IP address. The script is on this page:

http://www.changeip.com/clients.asp

It's the one by Bob Lee. In your zone file, make your MX record point to a hostname that is hosted at ChangeIP, and they'll update it whenever you change your IP address...