By default, dnsmasq stores DHCP lease information in RAM. This means that operations like a reboot will erase the lease database, forcing a new one to be created. This could be inconvenient, since devices might receive a new IP address after DHCP renewal. For dnsmasq to maintain its DHCP lease information, your router needs persistent storage, (such as USB).

There are currently two approaches to resolving this. The first approach does not use scripting.

1. Under Advanced, go to to DHCP/DNS menu. In the Dnsmasq Custom configuration field, enter:
   

   dhcp-leasefile=/mnt/usb/dnsmasq/dnsmasq.leases \\ 

2. Use a path relative to your own system. Click Save.
   
3. The goal here is to store the lease database on permanent storage. This can be useful, for example, when devices are connected to a switch. Using permanent storage means client devices won't lose connectivity if the router reboots. Moreover, they won't display in the Device List as having an active lease in the Device List until their current lease expires, and they request a new one. FreshTomato will just continue where if left off.
4. Please also notice the example points to a USB device with label “usb”. You might have different names on your system, depending on how the storage was formatted. This also means you can store the data on different permanent storage, such as a CIFS share. However, for this specific operation, you are not advised to use JFFS as this latter is never recommended for frequent writes (as it would occur every time a new IP is dispatched).

2) A different approach is to keep the lease database in its default location and copy it to permanent storage at “halt” time to then restore it when the device runs the “init” at boot. e.g.

Administration/Scripts/Init

[ -f /mnt/usb/dnsmasq.leases ] && {
 sort -b -k 2 -u -z /tmp/var/lib/misc/dnsmasq.leases > /tmp/dnsmasq.tmp1
 sort -b -k 2 -u -z /mnt/usb/dnsmasq.leases > /tmp/dnsmasq.tmp2
 diff -a /tm
 kill -HUP `ps | grep 
 rm /tmp/dnsmasq.tmp1
 rm /tmp/dnsmasq.tmp2
}

Administration/Scripts/Halt

cp -f /tmp/var/lib/misc/dnsmasq.leases /mnt/usb/dnsmasq.leases

This method 2) can be used with any storage, JFFS included, where for USB (only) an alternative is to performed the save/copy within the Run after mounting/Run before unmounting on the USB page instead than the generic script section.