UCARP

UCARP is a super handy tool that helps two or more hosts share the same virtual IP address. This way, if one host has an issue, the other can jump in without a hitch—this is known as automatic failover.

What is UCARP?

The UCARP project is a user-friendly version of the Common Address Redundancy Protocol (CARP). It’s secure and doesn’t require any patents, making it a great alternative to VRRP, which has some complicated licensing issues.

Why Use CARP?

The CARP protocol has several strong points:

• It has very low overhead, meaning it doesn't use much bandwidth.


• Messages are cryptographically signed for added security.


• It works well across different operating systems.


• No need for extra dedicated network links between hosts!

How to Set Up UCARP?

If you’re ready to compile UCARP, here’s how:

1. cd into the directory with the source code and run ./configure. This configures the package for your system.


2. If you’re using an old version of System V, you might need to type: sh ./configure.


3. This step takes a little while. Just chill while it checks everything!


4. Next, type: make, which compiles everything.


5. You can also run tests by typing: make check.


6. If all goes well, install it with: make install.


7. If you want to clean up later, just type: make clean.

Your Requirements for UCARP

You’ll need:

• A shared virtual IP that will be answered by whichever host is alive.


• A real IP address for each host involved.


• A shared identifier for the virtual IP (a number between 1 and 255).


• An advertisement time base (default is 1 second) so hosts know when to check in with each other.


This tiny packet won’t impact your network at all!