Network Segmentation Approaches

Christopher Morrow morrowc.lists at
Wed May 6 21:25:23 UTC 2015

this is really a form of: "A subnet should contain all things of a
like purpose/use."

that way you don't have to compromise and say: "Well... tcp/443 is OK
for ABC units but deadly for XYZ ones! block to the 6 of 12 XYZ and
permit to all ABC... wait, can you bounce off an ABC and still kill an
XYZ? crap... pwned."

segregation by function/purpose... best bet you can get.

On Wed, May 6, 2015 at 3:59 PM,  <charles at> wrote:
>> Consider setting up a separate zone or zones (via VLAN) for devices
>> with embedded TCP/IP stacks.  I have worked in several shops using
>> switched power units from APC, SynAccess, and TrippLite, and find that
>> the TCP/IP stacks in those units are a bit fragile when confronted
>> with a lot of traffic, even when the traffic is not addressed to the
>> embedded devices.
> Yes! This.
> I used to have my PDUs/term serves/switches all on one VLAN. As growth
> occurred, they get broken out to dedicated VLANs. With that, the amount of
> false positives from Zenoss went way down (frequently port 80 would report
> down, then clear). I still get some alerts, but far less frequently.

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