1. Download noip2 source.

cd ~/Downloads
wget http://www.no-ip.com/client/linux/noip-duc-linux.tar.gz
tar xvzf noip-duc-linux.tar.gz
cd noip-2.1.9-1/

2. We compile it with -O3 optimization given as CFLAGS variable and install it to /opt/noip. So modify Makefile to reflect those changes (see line numbers).

CFLAGS=-O3 -Wall -g

PREFIX=/opt/noip

${TGT}: Makefile ${TGT}.c
        ${CC} ${CFLAGS} -D${ARCH} -DPREFIX=\"${PREFIX}\" ${TGT}.c -o ${TGT} ${LIBS}

3. Compile and install.

make
sudo make install

4. During the installation give in all no-ip details like username, password, no-ip domain name etc, which is similar to configuring the Windows client. The configuration file will be saved to /opt/noip/etc/no-ip2.conf. Now change the ownership of the directory to the logged in user so that no-ip can read the config file.

cd /opt
ls -la # see the ownership
sudo chown -R user:group noip  # replace user and group with your username and group most likely would be your username.

# So if your username is foo, and belongs to foo (most likely is), then run 
# sudo chown -R foo:foo noip

ls -la 
cd noip && ls -la # check ownership has been updated.

5. Setup start-stop script. We can change the prefix, optimization and such by editing the Makefile.

#Install killproc
wget ftp://ftp.suse.com/pub/projects/init/killproc-2.13.tar.gz
tar xvzf killproc-2.13.tar.gz
cd killproc-2.13/
make && sudo make install

6. Create a file /etc/init.d/noip with the following content.

#! /bin/sh
# . /etc/rc.d/init.d/functions
# uncomment/modify for your killproc
case "$1" in
    start)
    echo "Starting noip2."
    /opt/noip/bin/noip2
    ;;
    stop)
    echo "Shutting down noip2."
    killproc -TERM /opt/noip/bin/noip2
    ;;
    *)
    echo "Usage: $0 {start|stop}"
    exit 1
esac
exit 0

7. Now we can start and stop the service using:

/etc/init.d/noip start  # start
/etc/init.d/noip stop   # stop

8. Add the service to update-rc.d to auto start at system startup.

cd /etc/init.d/
sudo update-rc.d noip defaults

9. Check if the IP is updated by logging into the noip.com website. If you are using a CNAME alias, say www of your domain name to this dynamic IP, you can check it using nslookup.

nslookup www.example.com