That chubby swede (sleepy) wrote,
That chubby swede

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[technical rant ahead]
I've studied a few ARM7 assembly language programming tutorials... it seems to be pretty easy (if you have coded assembly language on 68k and x86) to write code for that type of CPU... the trouble is to communicate to other devices... digging through chip spec's ... and getting the firmware in place... if I get hold of a JTAG cable and software to upload the compiled binary, I can always restore the firmware...

I figured that the DI-604 is brimful of jpegs and HTML... that waste valuable space... if removed it would provide space for extensions of functionality... it's got a total of 1Mb NVRAM and 4Mb of RAM to play with... I've already sketched on a few ideas... I'd trash can the HTTP/HTML interface completely, to replace it with a dummy HTTPD that only serves a minimal document with a meta-refresh to telnet://<ip-of-device:port> ... to make at least MSIE launch the default telnet application and connect to the user interface... a minimal telnetd wouldn't be that hard to find... and if a manual/guide/howto is needed it can always be hosted on the net somewhere...

It would also be useful with some kind of SPI (Stateful Packet Inspection) to filter both inbound and outbound traffic... filtering rules could be stored in RAM... not to use the valuable NVRAM... if powered off and on, it should run on a minimal set of rules such as...

  • drop packets on inbound that have private network addresses; 192.168.*, 172.16-31.*, 10.* and 169.254.*

  • drop packets on inbound ports 0-1024 TCP/UDP except DHCP (68/69 TCP/UDP) and use SPI to only allow negotiated ports through protocol monitoring

  • drop packets on outbound ports 135, 137-139, 5000 (NETBIOS and uPNP) TCP/UDP</i>
  • ...

... that would make a solid ground until additional rules are uploaded/entered over telnet, perhaps *nix/Win32 application...

the possibilities are endless... I found a page where somebody had disassembled a DI-604 and identified the chips, pin-outs and uncompressed the firmware image, had started to disassemble the parts of the firmware... but that person or his ISP (Comcast) probably got a cease and desist letter from DLink as the page weren't available anymore... got hold of it thanks to google cache.

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