Shucks Adam, I didn’t think you were snippy at all :). Listen, the only way to 
truly offend me is to take the last beer BEFORE the designated gofer for the 
night has Uber’ed his/her way back from the package store ;).

Stay Classy AP ;)

- RH

Sent from my iPhone

On Apr 30, 2019, at 13:20, Pawlowski, Adam 
<<>> wrote:

No snipe intended! Just been a rough day here.

Normally I wouldn’t get too far into details but, I feel like there are other 
customers out there who would have a similar network design with an in and an 
out, and it maybe be simpler to deploy this way, given the considerations.

And as always, I like to post and see what I can learn, especially from 
superstars such as yourself ☺


Adam Pawlowski

From: Ryan Huff <<>>
Sent: Tuesday, April 30, 2019 12:09 PM
To: Pawlowski, Adam <<>>
Subject: Re: [cisco-voip] Expressway E Firewall Rule Activation


I certainly didn't mean to imply the, "Expressway Edge on a Stick" method 
doesn't work, though out of pure technical curiosity, I would be curious as to 
what exists in your environment that would make a " single NIC" Expressway Edge 
deployment more preferred than "dual NICs" (not that I expect you would or 
could say). I can think of very few reasons that a single NIC edge would be 
more ideal than a dual NIC edge (outside of the infosec team just not wanting 
to screw with the firewall, or production not being able to sustain a 
maintenance window); its easier to troubleshoot, easier to install, easier to 
support and easier to secure.

Though, I suspect I'm, "preaching to the choir", lol 😉. All good my friend.



From: Pawlowski, Adam <<>>
Sent: Tuesday, April 30, 2019 11:36 AM
To: 'Ryan Huff'
Subject: RE: [cisco-voip] Expressway E Firewall Rule Activation


The “tl;dr” is that we were sort of given the recommendation by Cisco to just 
run it with the single interface given our environment and requirements, and 
hasn’t given us any trouble that I can recall.

Long story is …

Our environment ends up being the driver for a lot of this, as it is sort of a 
historic design from the early internet, with just about everything on public 
address space, and various services and networks secured behind firewalls as 
needed from internal and external alike.

In the dual interface design, the outside interface sits in a “DMZ” with a 
firewall, which we don’t have available explicitly. There is a border firewall 
but that isn’t really its function. The inside leg has to sit somewhere as 
well, which is a place that doesn’t exist.

We did have a competitor’s border proxy become compromised in the past due to a 
software update, and this model where the inside wasn’t properly secured – and 
given our current VMWare topology, creating another zone to hairpin traffic 
around to separate that inside interface wasn’t in the cards. Not to mention 
the annoyance of trying to setup split routes on this device to allow some 
traffic to go in, some to go out, in an environment that is MRA only.

If you trust the E enough never to be a bad actor, then you could put that 
interface in the same zone as your other collaboration appliances, like the 
Expressway C, but, we didn’t want to do that either really.

Given that, we did have a call with Cisco to discuss this, and with 
representation from the Expressway group they recommended that we stick with 
the single interface design.  That was based on the public addressing (so we 
could avoid NAT reflection) and that despite the pipe dream of everyone wanting 
HD video calling and mobile client access, we didn’t see that we’d be pushing 
that much traffic.

As it is, the E clusters sit in a collaboration DMZ, where they are independent 
from any of our other appliances and treated like any other host on our 
network. Our application firewalls do not allow anything in from the Expressway 
E since the C tunnels to it, so really the only thing lacking from a security 
standpoint there could be containment of that host, but, we chose to guard from 
it instead.

Since we installed it back on X8.8 or whatever, I’d noted that rebooting the 
appliance does not reapply the internal rules, which can easily be forgotten, 
and would need to be remembered if you run a VMWare HA policy that restarts the 

That all being said the worst that we have seen are various SSH attempts (on 
any port, the zone tunnel, administrative SSH, doesn’t matter) until the rules 
are put back up. We could tighten them on the border once that becomes 
available to do so.

The B2BUA is invoked on calls within the appliances sometimes which can cause 
some confusion with attempting to read logging if need be, but it hasn’t 
otherwise caused us any trouble.


From: Ryan Huff <<>>
Sent: Tuesday, April 30, 2019 10:13 AM
To: Pawlowski, Adam <<>>
Subject: Re: [cisco-voip] Expressway E Firewall Rule Activation

That seems odd and not been my experience. Let me ask; why are you using the 
application firewall rather than the actual firewall (another reason all our 
edge’s should be using dual interfaces with LAN1 and LAN2 in their own separate 
security zones)? Is there a reason you have to, in other words?



On Apr 30, 2019, at 08:49, Pawlowski, Adam 
<<>> wrote:

Figured I’d also ask this question

I note that it seems like any time I reboot an Expressway E, I have to go and 
re-activate all the firewall rules. They don’t seem to activate automatically.

Is there something I missed or is this really what’s necessary?


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