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RE: [FW1] OT - How secure is ISDN?
ISDN is as secure (or insecure, depending on your level of paranoia) as any
regular modem connection. I think security in the telephone network itself
is fairly good. The phone company central office where the ISDN switch is
located is a pretty secure facility. Highly unlikely that some hacker is
going to get into the CO with the equipment needed to sniff. ISDN is as
susceptible to "tapping" as any phone line for the portion of the connection
that travels in public space (on telephone poles, etc), but not many hackers
would go to the trouble of actually physically placing a tap. Because it is
a circuit-switched medium, the data channel is reserved entirely for your
use (like a private leased line), not shared with other user's data.
The real risk with ISDN, in my opinion, is the end-points, not the circuit
itself. War-dialing intrusion attempts could be made against the
remote-access server that terminates the ISDN call. Or if the remote site
is not physically secure, the client's machine could be owned and used to
gain entry via the ISDN link.
At a minimum, make sure any remote access server is OUTSIDE the firewall.
Dedicated (nailed-up) ISDN circuits (like Pacific Bell's Centrex ISDN
service) are a more secure than on-demand dial, since a hacker can't connect
to a number that's busy all the time. However, if the connection is hung up
for some reason, the door is open again. Many ISDN routers allow you to use
CHAP authentication to verify the calling device, which helps a lot.
Mark L. Decker
Rainfinity
[email protected] <mailto:[email protected]>-----Original Message-----
From: [email protected]
[mailto:[email protected]]On Behalf Of Ivan
Fox
Sent: Tuesday, October 17, 2000 8:01 PM
To: Fw1-Wizards (E-mail); fw-1-mailinglist (e-mail)
Subject: [FW1] OT - How secure is ISDN?
This question may have been asked many many times!
Am I correct/right to say that data travel through ISDN, no matter it is
dedicated or not, is not "unsecured". Data can be sniffed by third parties.
There is a need to deploy "firewall" for it.
Your pointers/comments/suggestions are appreciated.
Thanks,
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