MikroTik RouterBoard RB133

This device is NOT RECOMMENDED for future use with OpenWrt due to low flash/ram.
DO NOT BUY DEVICES WITH 4MB FLASH / 32MB RAM if you intend to flash an up-to-date and secure OpenWrt version onto it! See 4/32 warning for details.

1) This device does not have sufficient resources (flash and/or RAM) to provide secure and reliable operation.
This means that even setting a password or changing simple network settings might not be possible any more, rendering the device effectively useless. See OpenWrt on 4/32 devices what you can do now.

2) OpenWrt support for this device has ended in 2022.
19.07.10 was the last official build for 4/32 devices.

:!: See also forum for installation instructions.

:!: If you flash OpenWrt from NetBoot facility, you will lose your RouterOS licence.

The installation of OpenWrt on this board is only possible by using the NetBoot facility - you will boot into the RAMdisk version of OpenWrt and use it to flash the permanent OpenWrt image into NAND. You will need:

  1. A serial port (or a USB-RS232 serial converter) and a null modem cable as console (standard serial cable wont work).
  2. An ethernet port and cable to download the NetBoot kernel and the NAND image.
  3. A DHCP server to tell the RB1xx where to get it's netboot image (e.g. DnsMasq).
  4. A tftpd server to supply the NetBoot image to load a barebone OpenWrt RAMdisk image (e.g. DnsMasq).
  5. A web server to serve up the permanent version of the OpenWrt kernel and rootfs (you can use SCP as well).

Connect your RouterBoard using both ethernet and null modem cable to a PC.

See official howto for more info.

:!: If you select the squashfs image, it may take quite a few minutes for the device to power on.

You will have to run the building process twice, because you will need both RAMdisk image and stock OpenWrt kernel+rootfs.

Build profile should be:

  • Target System:
  • Target Profile:

To install openwrt on mikrotik rb133c a serial null modem cable is required on the local machine , an Ethernet cable , in addition to the proper functioning of a tftp and dhcp server on the local machine .

If the rb133c has already mounted openwrt you can directly go to the “ Writing nand ”

Once you have connected the serial cable and ethernet between rb133c and the local PC and you enable the tftp and dhcp server , copy the vmlinux file in the appropriate TFTP server root and start the serial console .

  minicom -d / dev / ttyUSB0 115200

then access to the serial console terminal , connect the rb133c power and press any key to blocccare the boot sequence .

RouterBOOT booter 2.18 
RouterBoard 133C CPU frequency : 175 MHz  
Memory size:  16 MB
Press any key within 2 seconds to enter setup.
your choice: e - format nand
Do you realy want to format your nand?
that would result in losing all your data
type "yes" to confirm: yes
formatting nand... done!
your choice: p - boot protocol
Choose which boot protocol to use:
   1 - bootp protocol
   2 - dhcp protocol
your choice: 2 - dhcp protocol
your choice: o - boot device
Select boot device:
   e - boot over Ethernet
   n - boot from NAND, if fail then Ethernet
   1 - boot Ethernet once, then NAND
   o - boot from NAND only
   b - boot chosen device
your choice: n - boot from NAND, if fail then Ethernet
your choice: x - exit setup
trying dhcp protocol.... OK
resolved mac address 00:26:B9:03:BC:3B
transfer started .............................. transfer ok, time=2.47s
setting up elf image... OK

If you already have in rb133c openwrt you can upgrade the firmware via ssh , or even by serial console .

root@OpenWrt:/# mkdir /mnt/kernel ; mount /dev/mtdblock2 /mnt/kernel
yaffs: dev is 32505858 name is "mtdblock2"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.2, "mtdblock2"
root@OpenWrt:/# mkdir /mnt/rootfs ; mount /dev/mtdblock3 /mnt/rootfs
yaffs: dev is 32505859 name is "mtdblock3"
yaffs: passed flags ""
yaffs: Attempting MTD mount on 31.3, "mtdblock3"
root@OpenWrt:/# passwd
Changing password for root
New password:
Retype password:
Password for root changed by root

Now back to your local machine , disable the DHCP server , then :

sudo ifconfig eth0 netmask up
scp openwrt-adm5120-rb1xx-vmlinux.elf root@
scp openwrt-adm5120-rb1xx-rootfs.tar.gz root@

Then return in the serial console to decompress the rootfs and restart the rb133c .

root@OpenWrt:/# cd /mnt/rootfs/
root@OpenWrt:/mnt/rootfs# gunzip openwrt-adm5120-rb1xx-rootfs.tar.gz
root@OpenWrt:/mnt/rootfs# tar xf openwrt-adm5120-rb1xx-rootfs.tar 
root@OpenWrt:/mnt/rootfs# rm openwrt-adm5120-rb1xx-rootfs.tar
root@OpenWrt:~# reboot

At this point the rb133c should listen to telnet to .

Linux howto

Windows howto

:!: Disable ANY firewall on your PC.

  1. Download Putty, run it, select Connection type: Serial, Serial line: COMx (x = number, depends on your configuration), Speed: 115200, and Open.

Atheros-based card are supported. The device doesn't work with Broadcom cards, since kmod-ssb causes kernel panic at startup.

Architecture MIPS
Vendor MikroTik, ADMtek (Infineon)
Bootloader RouterBOOT
System-On-Chip ADM5120 (Little Endian)
CPU Speed 175 Mhz
Flash size 64/128 MiB
RAM 32 MiB SDRAM (16 MiB on RB133C)
Wireless 3x Type III miniPCI slot (1x on RB133C)
Ethernet 3 x 10/100 Base-TX Ethernet Ports (with Auto MDI/MDIX) (1 on RB133C)
USB no
Serial yes
JTAG no?
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  • Last modified: 2024/02/12 08:58
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