sorry, not a pro, but would happily give you my opinion for what its worth.
Although its a .net, it may not let it down. The first thing i thought when i saw it was computer software.....i.e firewall etc, and in this case the .net is better.
Obviously, theres the other angle, being actual security firms (be it equipment, security services etc).
I think this name could fetch $2.5k, maybe even $5k if marketed well. Good domain, good chance of re-sale. Well done.