[isapros] Re: Came across this little gem...
- From: "Greg Mulholland" <gmulholland@xxxxxxxxxxxx>
- To: <isapros@xxxxxxxxxxxxx>
- Date: Wed, 30 Jan 2008 19:00:10 +1100
Ahh well done, must read entire thread before responding!
From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx] On
Behalf Of Thor (Hammer of God)
Sent: Wednesday, 30 January 2008 4:50 PM
To: isapros@xxxxxxxxxxxxx
Subject: [isapros] Re: Came across this little gem...
In XP, the VPN client DNS is prioritized, so it's not an issue. And in
Vista, you can tell it to "use the default gateway on the remote network" to
query the DNS server specified in the VPN connection.
t
From: isapros-bounce@xxxxxxxxxxxxx [mailto:isapros-bounce@xxxxxxxxxxxxx] On
Behalf Of Jim Harrison
Sent: Tuesday, January 29, 2008 9:11 PM
To: ISA Mailing List; ISAPros Mailing List
Subject: [isapros] Re: Came across this little gem...
Yep - these are the same geniuses that choose to respond for domains they
don't hold.
Case in point:
C:\>nslookup -d anyhost.corp.microsoft.com. 208.67.222.222
------------
Got answer:
HEADER:
opcode = QUERY, id = 1, rcode = NOERROR
header flags: response, want recursion, recursion avail.
questions = 1, answers = 1, authority records = 0, additional = 0
QUESTIONS:
222.222.67.208.in-addr.arpa, type = PTR, class = IN
ANSWERS:
-> 222.222.67.208.in-addr.arpa
name = resolver1.opendns.com
ttl = 82245 (22 hours 50 mins 45 secs)
------------
Server: resolver1.opendns.com
Address: 208.67.222.222
------------
Got answer:
HEADER:
opcode = QUERY, id = 2, rcode = NOERROR
header flags: response, want recursion, recursion avail.
questions = 1, answers = 1, authority records = 0, additional = 0
QUESTIONS:
anyhost.corp.microsoft.com, type = A, class = IN
ANSWERS:
-> anyhost.corp.microsoft.com
internet address = 208.67.216.130
ttl = 0 (0 secs)
------------
Non-authoritative answer:
Name: anyhost.corp.microsoft.com
Address: 208.67.216.130
What's the problem with this you may ask (go ahead - I triple-dog-dare ya)?
Take the case of the home (or small business) user chooses to use their DNS
in their NAT device.
In many cases, this NAT device also acts as the local network "DNS proxy" in
that the DHCP service it provides assigns its NAT IP (say; 192.168.0.1) as
the DNS server for the internal hosts.
Now let's this user has the ability to create a VPN connection to Microsoft.
When this connection is created, the VPN client has two DNS servers to
query; the local NAT DNS provided by the DHCP assignment and the DNS server
supplied via the VPN connection.
When Windows tries to resolve <host>.corp.microsoft.com, the closest DNS
server is the one defined in the non-DoD network, or 192.168.0.1.
This DNS server, being nothing more than a NAT reference to the OpenDNS
"services" replies to this request with an IUP address that is *not* found
within MS internal address space. Thus, the user can never make a
name-based connection across the VPN tunnel.
Apparently, they query the authoritative DNS services and if they come up
empty, the respond with an address anyway.
We tried working with them to stop doing this, but to no avail.
While my (real-life) example is Microsoft-specific, it would work if the
domain was ISAtools.org.
Consider using this "service" carefully; it'll bite you in the butt when you
least expect it.
Jim
From: isalist-bounce@xxxxxxxxxxxxx [mailto:isalist-bounce@xxxxxxxxxxxxx] On
Behalf Of Steve Moffat
Sent: Tuesday, January 29, 2008 3:50 PM
To: ISA Mailing List; ISAPros Mailing List
Subject: [isalist] Came across this little gem...
Looks like this could very well compliment your ISA installs guys.
http://www.opendns.com
Thanks
Steve
Steve Moffat
Operations Director
Optimum IT Solutions
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