Re: DoS Alcatel ADSL Modem Speed Touch Home

[Ed Rolison <ed.rolison () byzantium com>]

> Hi,
>
> While playing around with my new ADSL connection I found out that when you
> portscan the ADSL modem it crashes.
> I used NMAP and tried it locally -nmapping rfc1918 IP- and also from outside
> nmapping through mine PPTP connection, in both cases after a while the modem
> crashes, and the only thing I can do is reset the Modem.
>
>
> I tried to upgrade the firmware but the problem stays.
> I used KHDSAA 134 (988348) and KHDSAA 132 (986865)

Is your ADSL NATing? If so, then if you scan from inside, then it opens NAT
connections, and has to maintain an entry in a connection table.

Do a portscan, and it has to maintain a LOT of NAT connections (one per port per
host) and this can rapidly cause memory exhaustion.

Your router is not the only NAT device which exhibits this problem :)

(I'm assuming stuff, based on your mail but the fact that you are using RFC1918
indicates that there is NAT in there somewhere :))

--
Ed Rolison
Systems Admin
ER706-RIPE
ed () byzantium com