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The Alcatel SpeedTouch Pro is an interesting device. It appears to be a
professional unit, although many people have found that the firmware is
quite buggy. The bugs may not relate to all firmware versions, but
definitely relate the the ones used in modems supplied by my ISP.
The Alcatel policy on firmware upgrades is that they are to be supplied by
your ADSL Service Provider. This may be good for a large ISP, but for
smaller ISP's with few support people this is a joke. This leaves the only
realistic solution to be working arround the issues.
I have found some issues with the Alcatel Speedtouch Pro. The issues are
| NAT/PAT connections being lost after the modem is on for some time.
Pinhole-ing incoming connections being lost on restart |
I will now describe my symptons and what I have done to minimise the
problems caused by these issues. For reference I am running PPPoE.
NAT/PAT
Network Address Translation or Port and Address Translation allows the MODEM
to use a IP address assigned by the ISP to be used by a number of computers
on a network behind the modem. The unit translates outgoing connections so
that they originate from the address of the modem rather than the address of
the computer coming from a different port on the modem.
What I have found is that after a time outgoing connections are lost - where
hosts attempt to send packets out through the modem, and the modem has no
idea about the connection that the packets relate too. For some reason the
modem has killed the connection before the computer has.
I have found that the most reliable way to fix this is to reset the MODEM
every three hours. I have tried other values, but three hours seems to work
the best. I wrote a short script which starts a TELNET connection to the
modem and performs a power on reset. This works very reliably.
The only issue with this is that connectivity is lost for about 20 seconds
or so whilst the connection re-initiates. This is a small price to pay for
the improved reliability.
Pinhole and Defserver
The incomming connections to the public IP address can be handled in a
number of ways. By default any incoming connection is ignored. When there is
a need to connect servers to the modem there are a couple of ways to open
the modem.
The first option is to open the modem by port number creating a pinhole
allowing packets in. This works well, until the modem is reset in any way.
Upon reset the pinholes seem to be lost for some reason. I have not managed
any way to save this information without it being lost.
There is an alternative - DEFSERVER. This command allows a default
server to be set up for all unknown connections. By setting a DEFSERVER
ADDR=1.2.3.4, all incoming connections are sent to the IP address of
1.2.3.4. This works well, and will be saved.
The only complication for me is that I want to have my Firewall handle SMTP
traffic, and my Webserver handle WWW traffic. To do this I send all traffic
from my modem to my WWW server. I create a DNAT rule on my firewall
transfering all SMTP traffic intended for the WWW server to the FIREWALL,
and then inform the firewall to send SMTP traffic that it has verified to a
2nd private IP address for the firewall. Despite sounding complex, this
works well.
In practice thins are a bit more complex since I have two WWW servers in a
redundant array, but we can igore that complication for this discussion.
Anyway I hope this information has proved useful.
You might want to check out Alcatool which provides a
WWW interface to configuring the SpeedTouch
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