For those who want to start some firmware hacking!
Uncrypt the firmware by doing this:
$ des -k "n4100pro" -D N4100Plus_FW.2.0.04.3.bin fw.tgz
As you see the key is n4100pro !

Unpack the file the file fw.tgz
$ tar xvzf fw.tgz
And Voila!

upgrade/
upgrade/rc
upgrade/diff
upgrade/ca-bundle.crt
upgrade/conf.db
upgrade/cfg_nic1
upgrade/zImage.md5
upgrade/pre_message
upgrade/up.sh
upgrade/roaming
upgrade/ramdisk.arm.md5
upgrade/ramdisk.arm
upgrade/server.crt
upgrade/server.key
upgrade/httpd.conf
upgrade/passwd
upgrade/ssl.conf
upgrade/version
upgrade/rc.factory
upgrade/zImage
upgrade/manifest.txt
upgrade/php.ini
upgrade/crond.conf
upgrade/conf.db.awk
Happy Hacking!!

Dan.