One of the products that I've gotten a chance to work with, here at 3Sharp, has been PostPath. Billed as a Microsoft Exchange alternative, it is a set of Open Source packages and management tools that emulate an Exchange server in an Active Directory environment. I am not doing a lot with this product at the moment, but when I was setting it up, I ran into a couple of problems. While I was able to work around them, I thought that I would talk about the two major problems that I ran into.
Installing the host OS
When I started this install, I was using an ISO of the CentOS 4.6 DVD, targeting a VM. While the install seemed to go along fine, I made sure to pick the settings that were going to impact the end result. In particular, I made sure to leave a big chunk of space on the drive to format as XFS for the mail store. The other thing that I was particular about was turning off the firewall, since I have a nice ISA server already, and I didn't want to worry about port conflicts. I ran through the install a couple of times to experiment with the best selection of packages. I did try installing a GUI, but I decided that was a bad idea when it took me a full 10 minutes to get the video to display correctly. In a production Linux server, there should be very little need for a GUI, but I thought it would be a fun experiment.
Once I had the host installed and configured and updated, I thought that it was now time to move into the install of the PostPath product.
Installing PostPath
From the start, I was experiencing problems with the host OS. I was using Putty to SSH into the VM so that I would be able to cut and paste and work is just a more familiar and forgiving environment than the VMRC console. Using wget and the link they provided, I started to download the software. About halfway through, I was disconnected from my SSH session. After trying to reconnect and having no luck, I decided to log in to the console, but nothing seemed to be wrong. Keeping an eye on the file size, I was able to know when the download was done, and it was time to do the install.
The install itself, was pretty simple and there are some good instructions on PostPath's web site and inside the installer itself. I did have to download some RPMs, but one of the steps was to add a PostPath repository, so I wasn't worried about too many incompatibilities.
Once everything was installed, I mail-enabled all the users and attempted to log in.
Not Quite as Advertised
Well, once I had everything installed, and configured (so I thought), I was quite surprised to find that I was unable to get to the web mail site. After looking at the install closely, I couldn't find anything that was incorrect, so then I looked at the OS. Well, imagine my shock when I noticed that IPTables was turned on! No wonder I wasn't able to get to the site. After stopping the service and using chkconfig to ensure that it didn't come back on again, I was able to get to the site. Once on the site, I was getting more errors. For some reason, I kept getting the message that a network error had occurred. Just because I was a bit peeved, I restarted the server and hoped that I could start fresh after waiting a while for it to come back up.
Once the server was back up and running, I noticed that I was getting a bunch of connection failures from Samba. Seems that the box was unable to talk to our Domain Controller. After doing some digging, I noticed that the time was different from that of my desktop. Looking further, I noticed that NTP was turned off! No time sync = no Kerberos ticket = no connectivity for YOU! What was most surprising about finding that problem was that in the configuration stage for the OS, I distinctly set NTP to run and added the DC as the preferred time server. After adding the server back into the /etc/ntpd.conf and using good ole chkconfig again to make sure ntpd was going to run on all init levels, I started the service and then restarted all the PostPath services.
Success was mine, so far, as I was now able to log in to the web mail and see all that glorious mail goodness. While I did manage to get where I was going, it was fraught with frustration and I still haven't figured out why my SSH connections keep disconnecting and then not letting me back in. Some things I will just have to chalk up to "it's just Linux" even though I haven't had any problems with all the Ubuntu servers I've been running.
Wrapped Up With A Bow
Now that I have it up and running, and I'm able to send e-mail, the next step is to build up a rule to allow the inbound SMTP traffic from the firewall to my box (we have to wait for scheduled maintenance for any changes to production systems). Once that is done, I should be able to send and receive mail, push and pull mail from mobile devices, and access the web mail from the Internet. Once this is honking along, we'll see how good of a replacement it really is. I am really unhappy that it has taken so much work to get this running (as opposed to Exchange and Zimbra) but I am really glad to know that it is not the philosophy, but the particular distribution.