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Special Thanks go to GOPHER2005




Download and install snmp utilities from

Set the ip of your pc to,

netmask and def.gateway to


Llook up the hfc mac of your cable modem by going to and convert it to integer as follows: for example if it is 00:11:1A:02:CD:14 take the last 4 values and remove the colons resulting in 1A02CD14


Start windows calculator (calc.exe) and select scientific from the view menu


Select Hex and enter the value 1A02CD14, now select Dec and note down the integer value (436391188 )


Start your tftp server or use tftpd32.exe located in the FactoryMode_Bitfiles_actualizado03-12--2006_\TFTPD32+bitfile in the

Files And Video Section.also make sure the .bit file of your modem it located in the tftp root directory of your TFTP client.


Open a dos cmd window and navigate to where you installed snmpset example- C:\usr\bin\snmpset.exe


issue following command:

snmpset -v2c -c public i 436391188-that's an example use the value you calculated afer i.


observe which file the modem tries to tftp if should get sb****.bit and if write your modem should reboot.

.Once modem has rebooted keep ip the same

Open cmfirm3.exe

Close your tftp server as cmFirm has it`s own built-in.

Check your settings are the same but first make sure the firmware you want to flash is located in the tftp root as i explained earlier then click start.


Don't click anything until the modem has uploaded from cmFirm and rebooted.


When rebooted goto you should notice you now have the hack tab well done and enjoy!


Note this is for SB3100 , SB4100 and SB4200 modems only!

The Sb5100 upwards are not capable of this firmware change .