ASP authentification by ip-number

ASP authentification by ip-number

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Subject Author Date
ASP authentification by ip-number Ralph Wiggum 04-24-2008
Posted by Ralph Wiggum on April 24, 2008, 2:28 pm
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How safe is it to use the client's ip-number versus posting a username/password
(in cleartext) in an http request? Assuming the client's ip-number is static.

A common use-case would be a web-forum, where only VIP-users should have access
to specific topics. Authentification by ip is certainly the most user-friendly,
as user don't have register/remember passwords, no?

Is ip-spoofing considered easier than picking up unencrypted usernames/passwords
from web-traffic?

Posted by Roger Abell [MVP] on April 27, 2008, 2:39 am
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> How safe is it to use the client's ip-number versus posting a
> username/password (in cleartext) in an http request? Assuming the client's
> ip-number is static.

It's probably safer than a usr/pwd cred exchange in the clear.

> A common use-case would be a web-forum, where only VIP-users should have
> access to specific topics. Authentification by ip is certainly the most
> user-friendly, as user don't have register/remember passwords, no?

No. Yes, you are right, but after taking inital IP verified registration
and user being struck to registered IPs into account it seems that the
use-case gets pretty weak.

> Is ip-spoofing considered easier than picking up unencrypted
> usernames/passwords from web-traffic?

No in general, and certainly not for someone one a different subnet.




Posted by Steve Riley [MSFT] on April 28, 2008, 1:03 am
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Wrong approach. IP addresses identify machines, not humans. They are easily
spoofable, since they are always clear-text and are always unauthenticated.
Plus, with your approach, authorized users will be tied to specific
machines--they won't be able to access their information from other
computers.

User ID/password pairs are specifically designed for the scenario you've
described. Please use them.

--
Steve Riley
steve.riley@microsoft.com
http://blogs.technet.com/steriley
http://www.protectyourwindowsnetwork.com



> How safe is it to use the client's ip-number versus posting a
> username/password (in cleartext) in an http request? Assuming the client's
> ip-number is static.
> A common use-case would be a web-forum, where only VIP-users should have
> access to specific topics. Authentification by ip is certainly the most
> user-friendly, as user don't have register/remember passwords, no?
>
> Is ip-spoofing considered easier than picking up unencrypted
> usernames/passwords from web-traffic?


Posted by Ralph Wiggum on April 28, 2008, 5:14 pm
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Most of my users are behind their company's firewall. If I keep a database of
firewall ip-numbers and check incoming requests against the database, wouldn't
that be an ok solution?

Steve Riley [MSFT] wrote:
> Wrong approach. IP addresses identify machines, not humans. They are
> easily spoofable, since they are always clear-text and are always
> unauthenticated. Plus, with your approach, authorized users will be tied
> to specific machines--they won't be able to access their information
> from other computers.
>
> User ID/password pairs are specifically designed for the scenario you've
> described. Please use them.
>

Posted by S. Pidgorny on April 28, 2008, 5:51 pm
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No - for the same reasons. Why do you need extravagant authentication-like
schemes when many proper ways of authentication are available?

If you just need to allow certain IPs to access the Web site, just configure
restrictions and use anonymous access.

--
Svyatoslav Pidgorny, MS MVP - Security, MCSE
-= F1 is the key =-

* http://sl.mvps.org * http://msmvps.com/blogs/sp *

> Most of my users are behind their company's firewall. If I keep a database
> of firewall ip-numbers and check incoming requests against the database,
> wouldn't that be an ok solution?
> Steve Riley [MSFT] wrote:
>> Wrong approach. IP addresses identify machines, not humans. They are
>> easily spoofable, since they are always clear-text and are always
>> unauthenticated. Plus, with your approach, authorized users will be tied
>> to specific machines--they won't be able to access their information from
>> other computers.
>>
>> User ID/password pairs are specifically designed for the scenario you've
>> described. Please use them.
>>



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