W
Will
I'm having some problems with firewall authorizations for Windows Update
access in a DMZ. In general, I have had good luck getting access to
Windows Update when you authorize passage of HTTP, HTTPS, and FTP to these
networks:
131.107.0.0 / 16
207.46.0.0 / 16
64.4.0.0 / 18
65.52.0.0 / 14
In addition, I normally authorize these URLs for both http: and https:
*.microsoft.com
windowsupdate.microsoft.com
*.windowsupdate.microsoft.com
download.windowsupdate.com
The problem I am having is that occasionally the DNS name
"download.windowsupdate.com" resolves to some IPs on a huge network from the
Limelight load balancing farm. When the client behind the firewall
resolves that DNS to an IP, it then connects to the IP and the IP does NOT
reverse back to the DNS name download.windowsupdate.com. Instead it
resolves to some arbitrary name at the Limelight Network. So the firewall
has no way of knowing that the connection is authorized. Further
complicating all of this, download.windowsupdate.com does not always resolve
to the Limelight load balancers. Microsoft appears to have these IPs
pointing to load balancers all over the world. Some of the IPs I saw the
download.windowsupdate.com domain name resolve to:
208.111.148.50
8.12.217.124
192.78.223.126
209.84.2.124
etc
Microsoft provides a set of DNS names to use with the ISA firewall, and
naturally that doesn't work for the IPs above because they don't reverse to
Microsoft domain names.
No way do I want to authorize the entire Limelight load balancing network
into my DMZ. There are a huge number of IPs, and those are probably
associated with many hundreds of different organizations. When I do a
whois on the IPs Microsoft is using, nothing in the huge range of IPs
returned suggests which subset of the range is reserved for Microsoft use.
It would be really really nice for those of us who actually think about
security if Microsoft would publish openly the range of IPs it is using for
Windows Update. Failing that, I am open to ideas here about how can one
set up a reasonable set of firewall rules to securely connect to this
wideranging set of IPs.
--
Will
access in a DMZ. In general, I have had good luck getting access to
Windows Update when you authorize passage of HTTP, HTTPS, and FTP to these
networks:
131.107.0.0 / 16
207.46.0.0 / 16
64.4.0.0 / 18
65.52.0.0 / 14
In addition, I normally authorize these URLs for both http: and https:
*.microsoft.com
windowsupdate.microsoft.com
*.windowsupdate.microsoft.com
download.windowsupdate.com
The problem I am having is that occasionally the DNS name
"download.windowsupdate.com" resolves to some IPs on a huge network from the
Limelight load balancing farm. When the client behind the firewall
resolves that DNS to an IP, it then connects to the IP and the IP does NOT
reverse back to the DNS name download.windowsupdate.com. Instead it
resolves to some arbitrary name at the Limelight Network. So the firewall
has no way of knowing that the connection is authorized. Further
complicating all of this, download.windowsupdate.com does not always resolve
to the Limelight load balancers. Microsoft appears to have these IPs
pointing to load balancers all over the world. Some of the IPs I saw the
download.windowsupdate.com domain name resolve to:
208.111.148.50
8.12.217.124
192.78.223.126
209.84.2.124
etc
Microsoft provides a set of DNS names to use with the ISA firewall, and
naturally that doesn't work for the IPs above because they don't reverse to
Microsoft domain names.
No way do I want to authorize the entire Limelight load balancing network
into my DMZ. There are a huge number of IPs, and those are probably
associated with many hundreds of different organizations. When I do a
whois on the IPs Microsoft is using, nothing in the huge range of IPs
returned suggests which subset of the range is reserved for Microsoft use.
It would be really really nice for those of us who actually think about
security if Microsoft would publish openly the range of IPs it is using for
Windows Update. Failing that, I am open to ideas here about how can one
set up a reasonable set of firewall rules to securely connect to this
wideranging set of IPs.
--
Will