Certified: The Security+ Prepcast

In this episode, we’re exploring the security roles of network devices and appliances. Specifically, we’ll look at how device attributes—like whether something operates actively or passively, or whether it’s deployed inline or in monitor mode—affect your architecture. We’ll also examine key network appliances including jump servers, proxy servers, and intrusion prevention and detection systems. These technologies shape how administrators manage access, analyze traffic, and defend against threats.
Let’s begin with device attributes—starting with the difference between active and passive devices. An active device participates in network traffic. It can take actions, enforce policies, and modify or block traffic based on rules. An intrusion prevention system is a good example. When it sees something malicious, it stops it in real time.
A passive device, on the other hand, observes but does not intervene. It monitors network traffic and logs activity for analysis but cannot directly block an attack. An intrusion detection system is the classic example. It alerts administrators when suspicious behavior is detected but relies on someone else to respond.
The distinction is important because it affects how quickly threats can be mitigated and how much risk is introduced if the device fails. Active devices introduce latency and may block legitimate traffic if misconfigured, but they provide real-time protection. Passive devices are safer to deploy and offer valuable visibility, but they don’t stop attacks on their own.
Now let’s look at inline versus tap or monitor mode deployments. An inline device sits directly in the path of network traffic. All packets flow through it. This is how most intrusion prevention systems and next-generation firewalls are deployed. Because they’re inline, they can analyze and act on traffic in real time. The benefit is that they can enforce security policy immediately. The drawback is that if the device fails, it could create a bottleneck or take the network down—unless it’s designed with a fail-open or fail-closed setting.
A tap or monitor device connects to a network span or tap port. It gets a copy of the traffic but does not sit in the path. Intrusion detection systems and forensic monitoring tools often operate this way. The advantage is that they are non-intrusive—meaning they can’t break the network. The downside is that they cannot block anything—they only observe.
Choosing between inline and monitor mode comes down to your risk tolerance, performance needs, and the criticality of the systems being protected.
Now let’s move on to key network appliances—starting with jump servers. A jump server, also called a jump box, is a hardened device that acts as a gateway for administrators accessing secure systems. Rather than allowing direct remote access to production servers, admins connect to the jump server first. From there, they can reach other internal devices.
Jump servers centralize control and reduce the attack surface. They allow organizations to log all administrative sessions, enforce access policies, and monitor behavior. Ideally, jump servers are tightly secured, monitored in real time, and configured to use multi-factor authentication. All admin traffic flows through this single point, making it easier to audit and detect anomalies.
A common deployment might involve placing the jump server in a DMZ or isolated management zone. Administrators connect through a VPN, authenticate to the jump server, and then initiate secure sessions to internal systems. This setup provides visibility, containment, and centralized policy enforcement.
Next, let’s discuss proxy servers. A proxy server sits between users and the internet. It handles requests on behalf of clients, filters traffic, and enforces browsing policies. Proxies can serve multiple purposes: they can cache content to improve performance, scan traffic for malware, block access to prohibited websites, and even anonymize outgoing requests.
Security-focused proxies include web filters, content gateways, and cloud access security brokers. These tools inspect HTTP and HTTPS traffic, log user behavior, and enforce security policies based on categories, domains, or content types. Transparent proxies operate without user configuration, while explicit proxies require client-side setup.
Proxies are especially valuable for controlling outbound traffic. If a user clicks a phishing link, the proxy can block the request before it ever leaves the network. If malware tries to reach a command-and-control server, the proxy can detect and stop the connection.
Now let’s return to intrusion detection systems and intrusion prevention systems. We’ve already touched on their active versus passive roles, but let’s go deeper into their deployment and limitations.
An intrusion detection system, or IDS, analyzes traffic and alerts administrators to suspicious behavior. It’s best used in environments where real-time enforcement isn’t feasible or where you need a secondary layer of visibility. An IDS often monitors traffic on internal segments or mirrors packets from external firewalls. It’s useful for spotting reconnaissance, policy violations, or insider threats.
An intrusion prevention system, or IPS, actively blocks malicious traffic. It must be placed inline and configured with rules that match known threat signatures or behavior patterns. Modern IPS devices use deep packet inspection, application awareness, and behavioral analytics to detect complex threats like buffer overflows, command injection, and brute-force attacks.
The effectiveness of an IPS depends on rule tuning. Too loose, and threats get through. Too strict, and legitimate traffic is blocked. High-quality IPS deployments use baseline analysis, threat intelligence integration, and automated updates to stay effective. They must also be fail-safe—able to gracefully handle traffic during maintenance or unexpected failures.
As you prepare for the Security Plus exam, be ready to explain the difference between active and passive devices, describe the trade-offs of inline versus monitor deployment, and recommend appliances like jump servers or proxy servers for specific use cases. You may be given a scenario where a system is compromised and asked to identify which device would have detected or blocked the activity. Focus on visibility, control, and the balance between performance and enforcement.