I've been doing some searching on a macOS server and have noticed that there's an open port that I am able to access outside the network. When I go to this port it will ask for a username and a password, once logged in it provides a Collection listing that looks kinda like the following:

Collection Listing
   Name                   Size   Last Modified      MIME Type
.calendarsystem_version     1   2014-Jun-09 09:51   text/plain
.well-used/                 ?                       (collection)
addressblocks/              ?                       (collection)
user/                       ?                       (collection)
apns                        ?                       text/html
.calendars/                 ?                       (collection)
.directory/                 ?                       (collection, addressbook, directory)
principals/                 ?                       (collection)
timezones                   ?                       text/xml (timezones)
webcal                      ?                       (collection)

My only problem is, I have no idea what this is. It seems to be some sort of listing for development, from what I've gathered with nmap it shows as 8443/tcp open https-alt.

I have two questions regarding this:

  • What is this port open for/what is it?
  • Would it be a good idea to close this port?

What is this port open for/what is it?

From Apple's support site TCP and UDP ports used by Apple software products:

8443 - TCP - iCal service (SSL) - pcsync-https
Mac OS X Server v10.5 or later (JBOSS HTTPS in Mac OS X Server 10.4 or earlier)

Thus, it looks like a calender service which explains names like .calendarsystem_version.

Would it be a good idea to close this port?

This depends if you need this service or not.

  • That makes sense. So why is it open off the network is the real question than..? – CertifcateJunky Apr 9 '18 at 17:40
  • @CertifcateJunky: likely because somebody has enabled the iCal service on the machine. Maybe a misconfiguration, maybe intentional - ask the one who manages this system. – Steffen Ullrich Apr 9 '18 at 17:43
  • Awh, that makes sense. I seem to have found the issue. Thank you for helping! – CertifcateJunky Apr 9 '18 at 17:54

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