Its theoretically possible to take the CUCM tomcat CSR and use it to get LE to 
sign a cert, then take the resulting cert and attempt to upload it to CUCM 
however; if it worked, LE only signs certificates for 90 days. So if you did 
get it to work, you'd have to do it every 90 days (the built in LE package on 
other Linux distros have built in tools to auto manage the renewal process, but 
no way to do it with CUCM).


... but thats if the moon is blue and you have a winning lotto ticket. To even 
get to that point, would be a feat; let me explain.


The way LE for Linux signs certs is to install local software on the web server 
that will do an automatic Internet based FQDN check (meaning it automatically 
looks up the FQDN from the perspective of the Internet) during the signing 
request. Once it finds the domain, it queries for a specific item within the 
web path to verify that domain belongs to the same person that started the 
certification signing request (this isn't a lot different than the way Google 
or GoDaddy does it). However, the CSR must exist in a specific location on the 
server you are trying to sign the cert for. Once all criteria is met, LE 
automatically creates a vaild SSL certificate for the web server that is signed 
for 90 days and installs it on the web server.


So in order to even try and get this to sign a cert for a CUCM CSR you'd have 
to;

  *   Create an Internet facing Linux web server that mimics all the network 
details of the CUCM server and try to get LE to sign the CUCM CSR on that web 
server (you'd take CUCM's CSR and upload it to the Linux Web Server).
  *   Extract the signed .pem from the web server and attempt to upload to CUCM 
as a tomcat (you'll also need to grab LE's root CA and upload it to the 
tomcat-trust)


In theory it might work, but is a helluva effort for 90 days just to get free 
certs, then do it all over again. Now if you got it to work and had a good 
workflow every 90 days ... maybe not that bad? The other thing to consider that 
I'm not sure about in CMR cases (thinking if you tried this on an Expressway 
Edge) is if Cisco Collab Cloud (i.e WebEx) would trust the CA.


Thanks,


Ryan


________________________________
From: cisco-voip <cisco-voip-boun...@puck.nether.net> on behalf of Lelio 
Fulgenzi <le...@uoguelph.ca>
Sent: Tuesday, September 26, 2017 10:00 AM
To: voyp list, cisco-voip (cisco-voip@puck.nether.net)
Subject: [cisco-voip] let's encrypt for local admin gui pages




Has anyone been successful in deploying Let’s Encrypt certificates on appliance 
based gui’s? Seems like Let’s Encrypt is a cloud based service, which has proxy 
support, but it’s still client based with short certificate periods.





---

Lelio Fulgenzi, B.A.

Senior Analyst, Network Infrastructure

Computing and Communications Services (CCS)

University of Guelph



519-824-4120 Ext 56354

le...@uoguelph.ca

www.uoguelph.ca/ccs

Room 037, Animal Science and Nutrition Building

Guelph, Ontario, N1G 2W1


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