Quick guide for installing OpenWrt on a Mikrotik mAP lite.

• Download the network boot image to a network boot location. initramfs-kernel
• Download the sysupgrade archive, you need to serve this over http. squashfs-sysupgrade

  python -m SimpleHTTPServer 8000

• Configure a network boot server, e.g. dnsmasq: /etc/dnsmasq.d/server.conf

  ...
  enable-tftp
  tftp-root=/var/lib/tftp
  dhcp-boot=/var/lib/tftp/maplite/openwrt-18.06.1-ar71xx-mikrotik-rb-nor-flash-16M-initramfs-kernel.bin
  ...

• Connect the mAP lite to ethernet (network boot network).
• Press the reset button, connect power (USB).
• Wait until LEDs flash (about 5 seconds) then release the button.
• Connect to the mAP lite via wifi (ethernet is not available for connecting to).
• Modify settings for network boot (the 'try ethernet once' setting is not persistent across reboots).

  System → Routerboard → Settings → Boot device: Try ethernet once then NAND
  System → Routerboard → Settings → Boot protocol: DHCP
  System → Routerboard → Settings → Force Backup Booter: Checked
  
  system -> shutdown

• Unplug and replug power.
• After a while (monitor your dnsmasq logs, tcpdump etc), you can ping the mAP lite.

  # ip addr add 192.168.1.10/24 dev eth0
  # ping 192.168.1.1
  PING 192.168.1.1 (192.168.1.1) 56(84) bytes of data.
  64 bytes from 192.168.1.1: icmp_seq=1 ttl=64 time=1.64 ms
  64 bytes from 192.168.1.1: icmp_seq=2 ttl=64 time=0.789 ms
  64 bytes from 192.168.1.1: icmp_seq=3 ttl=64 time=0.730 ms

• You can now log in (SSH or HTTP) to the mAP lite, booted from network.

  # ssh  root@192.168.1.1                                                                                                 
  The authenticity of host '192.168.1.1 (192.168.1.1)' can't be established.
  Are you sure you want to continue connecting (yes/no)? yes
  Warning: Permanently added '192.168.1.1' (RSA) to the list of known hosts.
  
  
  BusyBox v1.28.3 () built-in shell (ash)
  
    _______                     ________        __
   |       |.-----.-----.-----.|  |  |  |.----.|  |_
   |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
   |_______||   __|_____|__|__||________||__|  |____|
            |__| W I R E L E S S   F R E E D O M
   -----------------------------------------------------
   OpenWrt 18.06.1, r7258-5eb055306f
   -----------------------------------------------------
  === WARNING! =====================================
  There is no root password defined on this device!
  Use the "passwd" command to set up a new password
  in order to prevent unauthorized SSH logins.
  --------------------------------------------------

• Install OpenWrt permanently on the mAP lite:

  root@OpenWrt:/etc/config# sysupgrade -n -v http://192.168.1.10:8000/openwrt-18.06.1-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin
  Downloading 'http://192.168.1.10:8000/openwrt-18.06.1-ar71xx-mikrotik-rb-nor-flash-16M-squashfs-sysupgrade.bin'
  Connecting to 192.168.1.10:8000
  Writing to '/tmp/sysupgrade.img'
  /tmp/sysupgrade.img  100% |*******************************|  3776k  0:00:00 ETA
  Download completed (3866975 bytes)
  Commencing upgrade. Closing all shell sessions.
  Connection to 192.168.1.1 closed by remote host.
  Connection to 192.168.1.1 closed.

• Remove the network boot host key.

  ssh-keygen -f "/root/.ssh/known_hosts" -R 192.168.1.1

• Wait until the installation to finish, this can take a minute or two.
• Log in on the mAP lite (SSH or HTTP):

  # ssh  root@192.168.1.1                                                                                                 
  The authenticity of host '192.168.1.1 (192.168.1.1)' can't be established.
  Are you sure you want to continue connecting (yes/no)? yes
  Warning: Permanently added '192.168.1.1' (RSA) to the list of known hosts.
  
  
  BusyBox v1.28.3 () built-in shell (ash)
  
    _______                     ________        __
   |       |.-----.-----.-----.|  |  |  |.----.|  |_
   |   -   ||  _  |  -__|     ||  |  |  ||   _||   _|
   |_______||   __|_____|__|__||________||__|  |____|
            |__| W I R E L E S S   F R E E D O M
   -----------------------------------------------------
   OpenWrt 18.06.1, r7258-5eb055306f
   -----------------------------------------------------
  === WARNING! =====================================
  There is no root password defined on this device!
  Use the "passwd" command to set up a new password
  in order to prevent unauthorized SSH logins.
  --------------------------------------------------