This guide will show you how to change the shared IP of your cPanel server with the method I’ve used in the past. This is intended for intermediate to advanced administrators that have some basic knowledge of cPanel and networking.  This will only update the main IP of your server, and will not affect accounts that have dedicated IPs or SSL certificates.

Update your TTLs

The first thing you need to set your zone TTL’s on the server to a lower value a day or two prior to changing the IP, so the caching period is lower.  Caching DNS servers should be configured to use the TTL value, and while all may not be configured to work this way, you should prevent inconvenience to most of your users by configuring the value as low as possible – usually to 3200.

There may be some methodical science behind this that you can come up with, but I found that the easiest way to do change the TTL’s for everyone on one server is with a simple replace:

replace 86400 3200 — /var/named/*.db

You can change the first value to whatever you have your default TTL set to, which is indicated in /etc/wwwacct.conf. After this, use the following script to increment up the serial numbers:

http://www.ndchost.com/cpanel-whm/scripts/updateserial/

Now sync the zones out to the cluster to update your nameservers:

/scripts/dnscluster synczone all

Add the new IP

A couple days after you make this change, add the new IP to your server. You can edit /etc/wwwacct.conf to indicate the interface and IP that should be shared, but I find that having the main IP also be the shared IP works best. The reason for this is that if you, for example, have the eth0:1 interface as the shared IP, each IP added after that as an alias will have an interface of eth0:1:x and won’t work properly.

To change the main IP of the server:

1. Edit /etc/sysconfig/network-scripts/ifcfg-ethx (ethx = adapter your public IP is on)
2. Modify IPADDR, NETMASK, GATEWAY and NETWORK to match your IP parameters (some may not be present)
3. Edit /etc/sysconfig/network to change additional parameters not preset in the previous file
4. Restart the network service

NOTE: This example refers to a Redhat-type system.  Actual file names you need to edit would differ depending on what flavor of Linux you’re on.

Update configurations

Now, all you need to do is run a few more replace commands:

• replace $oldip $newip — /var/cpanel/mainip
• replace $oldip $newip — /var/cpanel/userdata/*/*
• replace $oldip $newip — /var/named/*.db
• replace $oldip $newip — /etc/*
• service named restart
• /scripts/rebuildhttpconf

You also need to run the same script as before to update the zone serials again (now that they have new IPs) and sync the domains back up to the clusters. Then use the same replace command (only opposite) to change the TTL’s back to the original values.

To complete the change, I would advise running a cPanel update in case any internal cPanel files are using the previous IP.

Related posts:

1. Changing a Site’s IP Address
2. Changing Exim’s Sending IP
3. Installing an SSL Certificate on a Shared IP

1. Edit /var/cpanel/userdata/$USER/$SUBDOMAIN.$DOMAIN for each subdomain (for addon/parked domains you’ll usually edit the file for the subdomain associated with the addon/parked domain) and change the ip value to a ‘dedicated’ ip.

2. Run /scripts/rebuildhttpdconf

3. Edit the dns zone for the subdomain (which will likely be attached to the parent domain) and update the a-record to point to that IP as well. Then syncronize the zone out to the DNS cluster, if one exists:

/scripts/dnscluster synczone <parentdomain>

4. Edit /etc/domainips and add an entry for that sudomain to point to the IP and run /scripts/rebuildippool to make sure the IP is marked as taken.

Related posts:

1. How to Assign an IP To Multiple cPanel Accounts
2. Setting Up Wildcard DNS with cPanel
3. Resolving Domain Park Wrapper Errors

Via WHM:

Go to WHM  > Change site’s IP Address , select the account, then select the IP

Via Command Line:

/usr/local/cpanel/bin/setsiteip -u $user $ip

Manually:

-Edit /var/named/domain.com.db and increment the serial number. For help in changing DNS, see this post

-Replace instances of the old IP with the new IP in /var/cpanel/userdata and /var/cpanel/users

replace 123.123.123.123 222.222.222.222 — /var/cpanel/userdata/user/*

replace 123.123.123.123 222.222.222.222 — /var/cpanel/users/user

-If the new IP is shared, remove the user’s main domain entry from /etc/domainips. If it’s a dedicated IP, add/change the IP in /etc/domainips and /etc/ssldomains (if the site has an SSL)

-Run /scripts/rebuildhttpconf and /scripts/rebuildippool

Related posts:

1. Changing the Shared IP Address of a Live Server
2. Changing Exim’s Sending IP
3. How to Assign an IP To Multiple cPanel Accounts

Why?

You probably already know why you need more IPs on your server if you’re reading this, but humor me for a second. Here are a few reasons why you might need to add some more IPs:

• You are hosting multiple accounts/sites, some of which utilize SSL certificates. Apache requires each SSL certificate to have its own IP, and cPanel (currently) limits each account to one IP address…
• …So, you need to be able to assign sites to different IP addresses. Or  you host one of the idiots out there that thinks having each site on a separate IP is actually going to up their search engine rankings.
• You need more IP addresses to send email from, because your mail server’s IP is blacklisted
• You need to resolve routing or bandwidth problems between your server and other networks

cPanel utilizes the ipaliases service to process additional IP’s as virtual interfaces. Those of you already familiar with Linux IP aliasing using the ifcfg command probably already know that you can add an IP alias to, say, eth0, with the following command:

ifconfig eth0:0 123.456.789.123  netmask 255.255.255.0 up

While this would technically work, it’s not how cPanel wants you to do it. When it comes to safely adding IPs to a standalone server, you have two options:

• Add the IP in WHM
• Add the IP directly to the ipaliases configuration

Understanding the Process

When you add an IP to a cPanel server using a supported method, cPanel performs the following process:

1. Adds the IP as a alias to the main interface (usually eth0)
2. Rebuilds the IP Address pool (/scripts/rebuildippool ~> /etc/ipaddrpool)

The WHM Method

To add an IP address via WHM, you can simply log in as a root user and go to “Add a New IP Address”, enter the IP and its subnet mask, and hit “Submit.”

The Command Line Method

You can also add IPs via command line in a way that cPanel understands, which is mainly useful when doing automated server setups, or adding multiple IPs across multiple servers. To do this, you’d edit the ipaliases load file, which is /etc/ips . If you already have additional IP addresses on your server added as aliases you may already see how this file is formatted, but here’s an example:

123.456.789.123:255.255.255.0:123.456.789.255

This is a colon-delimited file with each IP address on its own line. The first field is the IP itself, the second is its subnet mask, and the third is its broadcast. You can add as many IPs as you need, putting each on its own line.  When you’re done, run the following commands:

service ipaliases reload (or service ipaliases restart)

/scripts/rebuildippool

To check whether the IPs have been added successfully, you can perform any of the following tests:

/scripts/ipusage  <~ will show the IP usage of the server

ifconfig <~ will show all IPs on the server

ping $ip <~ will ping the IP ($ip) you added to make sure it’s routing

Note that for many VPS/Virtualized platforms (like Virtuozzo, OpenVZ, etc), you have to add the IP through the parent node in order for it to work. For OpenVZ/Virtuozzo, you would do:

vzctl set $VEID –ipadd 123.456.678.123 –save  (pass –ipdel to remove an IP)

Then enter into the VPS and run /scripts/rebuildippool . In some cases you may also need to refresh the cPanel license:

/usr/local/cpanel/cpkeyclt

Removing an IP Address

Removing IP is exactly the opposite, where you can remove the IP from WHM ~> “Show or Delete Current IP Addresses” or by removing the IP lines from /etc/ips and reloading ipaliases.

Once you’ve added and assigned an IP to the server, cPanel will not let you remove it unless you change the IP address of the account using it to something else. If you want to override this, you can manually add the IP to /etc/ipaddrpool  and safely remove the IP via WHM. However, this in some cases has been known to unroute the other IPs on the server, so you’ll likely need to reload ipaliases again.

Related posts:

1. Mass Change Default (Catch All) Addresses
2. Adding Services to Chksrvd for Monitoring
3. Changing a Site’s IP Address