If you are lucky enough to run your flexlm servers on a tightly controlled corporate network then you probably just turn the firewall off on those servers and get on with your life. Everyone else goes through a certain amount of hair-pulling before they work out how to make flexlm play nicely with firewalls. So I’m writing this post to document the process as much for me as anyone else.

So let us say that you have bought five copies of Bob’s Magical Pony Viewer an awesome graphical client that you can run to show you ponies. In order for Bob to be sure that you only run five copies he has used flexlm to secure his software. You have received a network license for BobSoft that looks like:

SERVER license1 0000eeeeeeee 2020
VENDOR bobs_lm
FEATURE PonyL bobs_lm 1.0 06-jan-2011 5 \
SIGN="EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE \
EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE"

So you think, great we can set that up with only port 2020 open on the license server and everything will excellent. Ponies for five concurrent users, hurray!

Except of course when you try that Pony Viewer adamantly claims that it can’t contact the server. Even though you can netcat/telnet to port 2020 on that server and the flexlm logs tell you that the server is running just fine.

It’s helpful at this point to have a copy of lmutil around to debug the problem. I don’t know where to get lmutil from as it came bundled with the license server software from one of our vendors. But it’s very useful when trying to work out what is going on.

So lets try some things.

#>lmutil lmstat -c 2020@license1
lmutil - Copyright (c) 1989-2004 by Macrovision Corporation. All rights reserved.
Flexible License Manager status on Thu 1/21/2010 19:56

Error getting status: Server node is down or not responding (-96,7)


This is the point at which one normally starts with the hair-tearing. The thing to realise about a flexlm server is that it’s actually two daemons working together. The lmgrd which is running on port 2020 and the vendor daemon (in this case bob_lm) which will start up on a RANDOM port. What is even better is that the vendor daemon will choose a different random port every time you restart the license server.

While discussing this with some fellow sysadmins it turns out that there is another option you can add to flexlm license files which ends this misery. You can tell the vendor daemon to start on a specific port. Like so:

SERVER license1 0000eeeeeeee 2020
VENDOR bobs_lm port=2021
FEATURE PonyL bobs_lm 1.0 06-jan-2011 5 \
SIGN="EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE \
EEEE EEEE EEEE EEEE EEEE EEEE EEEE EEEE"


And now when we try lmutil

#>lmutil lmstat -c 2020@license1
Flexible License Manager status on Thu 1/21/2010 20:06

bob_lm: UP v11.6


Hurray Ponies!

One last thing to note make sure the hostname you specify in the license file matches the hostname of the license server and also the hostname you use when connecting to the server. This is because flexlm sends the hostname asked for as part of the license request and if the two don’t match you won’t get any ponies.

In short flexlm is a dreadful license server it’s just that all the others are even worse.