The latest Inc. 5000 list of the fastest-growing private companies contains dozens of IT services providers and MSPs. But that's not all. Dig a little deeper and you'll specifically find MSSPs (managed security services providers) and next-generation cybersecurity company that work extensively with channel partners.Skeptical? Here are just a few of the sample names we spotted on the Inc. 5000 list for 2017 -- along with some of our observations about each company. Note: Company growth rates are based on a three-year revenue window, with annual revenue figures based on 2016 results.AlertLogic, ranked 2441: Revenue grew 147 percent over the past three years, reaching more than $100 million in 2016. AlertLogic ranks among the Top MSSPs in North America, according to the Forrester Wave report for 2016. The company received a $70 million syndicated credit facility in June 2017.Cylance, ranked 301: Revenue jumped 1,454 percent, reaching $45.1 million. The company announced a new CFO hire in August 2017, triggering fresh speculation about a potential IPO. The company also launched consumer software in mid-2017. The goal: Allow employees to move seamlessly between work and home settings while continuing to ensure endpoint security.DirectDefense, ranked 169: Revenue rose 2,463 percent, reaching $5.9 million. The company offers a massive list of managed security services for end-customers.KnowBe4, ranked 231: Revenue grew 1,856 percent, reaching $10.1 million. The company also has marketing know-how. Among its smartest moves of 2017: Publishing a top 10 list of the most clicked phishing email subject lines.Malwarebytes, ranked 847: Revenue grew 532 percent, reaching $98.3 million. The company landed in Gartner's Magic Quadrant for endpoint protection platforms in 2017.Mosaic451, ranked 376: Revenue grew 1,149 percent, reaching $16.4 million. The company specialize in security operations center and network operations center services, among other things. Recent moves include a new EMEA (Europe, Middle East, Africa) partner program.Optiv Security, ranked 3897: Revenue jumped 74 percent to $2 billion. KKR, a private equity firm, acquired Optiv in late 2016. Financial terms weren't disclosed. But we poked around. Worked our sources. And... a few trusted folks told us the Optiv sale was worth $1.9 billion.That's just a sampling of the security-focused companies on the Inc. 5000 list for 2017. Check the list for dozens of addition examples