When you need to set up a TinyCore box with a fixed IP address, you have the following options:

• Configure the DHCP server of your router to assign a fixed IP to the hardware MAC address of your box.
  (the command ifconfig shows the hardware MAC address on its first output-line – HWaddr – )
• If you do not have access to your router, or if you don't want to meddle with its config,
  you must resort to disable DHCP on your TinyCore box.

Adding the boot parameter nodhcp to the grub.cfg file (or its cousin from syslinux) will disable DHCP on your box

You can also use either of these two alternatives below:

• Set NODHCP=1 at the beginning of /etc/init.d/tc-config and remaster.
• To avoid remastering, replace /etc/init.d/dhcp.sh with an empty script in a backup file.

To manually set the IP address for your box to the example value 192.168.2.128, enter the commands as given below:

ifconfig eth0 down
ifconfig eth0 192.168.2.128 netmask 255.255.255.0
ifconfig eth0 up

You can also add these commands to /opt/bootsynch.sh or /opt/bootlocal.sh

Forum Topic: Permanent disable DHCP + run script at startup