MikeL's FreeBSD howto - Change IP address

MikeL's FreeBSD howto - Change IP address

(Page last updated 23-Feb-2007)

This is basically a checklist of how to change your machine's IP address. The intent is not to cover everything in detail, merely to point you to each of the tasks that must be performed.

This list was created when I physically moved my FreeBSD server from a lower-speed connection to a high-speed data center co-location service. The assumption is that the box will be locked in a closet once configured, accessible only via the Intenet/ssh.

Don't forget to to have your upstream provider update the reverse DNS name of your IP address! If you're on a DSL or some such, by default this name probably indicates that you are a dialup, which will be blocked by many mail servers.

A few days before making the move:

edit /etc/namedb/<your-machine-hosts-file> and lower TTL, expire, and refresh values to a few hours. Obviously if you have multiple domains, you'll have to do them all. (If you don't already, this is sure to get you to convert to using common files which do include.)



Once the box has been moved:


Edit /etc/resolv.conf with new DNS server(s).

    (Of course the first line in the file will still be:
    domain=<your-domain-name>
    If you're running your own DNS/BIND server, you should have
    yourself listed first:

    nameserver=<your-server-ip>
    Followed by the DNS server supplied by your upstream provider:

    nameserver=<upstream-provider-server-ip>

Edit /etc/rc.conf with new gateway:

    Your upstream provider will supply you with the ip address of
    their gateway (amy also be called router) for your system:
    defaultrouter=ip-of-upstream-gateway

    You'll already have turned on your gateway with:

    gateway_enable="YES".

You'll change the new IP address in the ifconfig:

    ifconfig_<device=inet <your-new-ip>

    (I'm omitting other possible options in the ifconfig --
    that's your problem.)

Hopefully your ISP is forwarding the old IP address to the new for
    you, in which case you'll enter the old as an alias:

    ifconfig_lo0_alias0="inet <your-ol-ip>.

    (Again, I'm omitting other options in the ifconfig line.)

Edit /etc/rc.firewall with new onet
    and oip.

Reboot

You may need to get things working using manual
    ifconfig commands.

Keep at it until if you can ping somebody in the
    outside world (or in some way prove that the network is
    working).

From some external machine, make sure you can do an
    ssh inbound.

Make sure to update /etc/rc.conf with the final
    ifconfig.


    Once done, reboot machine so as to make sure you can still get out
    and in if you were to have to do a remote reboot.



Now that the box has been moved, and is up, you can lock up the box in
the closet, and go somewhere more comfortable to do the remaining
work:



Edit /etc/namedb/<your-system-hosts-file>.
    (Obviously this must be done for all domains on the box) and
    restart named.

Check /etc/mail/<your-systems.mc>.  Also check
    access file, regenerate cf file and restart
    sendmail if changed.

Edit /usr/local/etc/apache/httpd.conf and restart
    apache.  (All virtual domains.)

Edit /usr/local/etc/smb.conf and restart
    dhcp.

cd /usr/local/etc and grep <old-addr> *
    adding /* layers until you've checked all files6.

Go to your domain name registrar(s) and update them.

Go to dnsreport.com to
    check your work.

Don't forget to go to your DNS and mail
    secondarying machines and go through the same list of files on
    each.

Don't forget to go to inform anyone else who
    depends on your IP of the change; for example are you subscribed
    to RBL+ at mail-abuse.org?.  Do you have anyone doing secondarying
    for you?



A few days later, after the dust has settled:



Go back to dnsreport to ensure that all is still as you think it
    is.

Set time values in dns settings back to more reasonable values,
    like those recommended by dnsreport.



Please note!  restarting 'named' appears to rewite your /etc/resolv.conf file.






Copyright © 1995-2023


Mike Lempriere
(running on host pedicel)