Hiring a network security engineer: profile and interview

The network is still the first line of defence for most information systems, even when part of the applications have moved to the cloud. Yet the network security engineer role is often poorly scoped: sometimes you want a firewall administrator, sometimes an architect, sometimes an expert who can do everything. This guide helps you define the role, know what to check and assess candidates on concrete situations.

What a network security engineer does

A network security engineer designs, deploys and runs the controls that govern traffic across the information system. Their work comes down to one simple question: who can talk to whom, along which path, and does anyone see it?

Their most common responsibilities:

Filtering and segmentation: managing firewalls, defining zones, reviewing rules regularly, removing permissions that are no longer needed.
Remote access: VPNs, access for contractors and remote staff, integration with strong authentication and so-called "zero trust" access solutions.
Internet exposure: reverse proxies, web application firewalls, denial of service protection with the carrier, control of published services.
Network access control: authenticating endpoints and devices, isolating guest networks, connected devices and administration equipment.
Visibility: device logs, flows forwarded to the SOC, detection sensors, the ability to reconstruct a network exchange during an investigation.
Change management: handling flow opening requests, documentation, keeping what is written consistent with what is configured.

In a small team, the same engineer often also runs the network itself (routing, switching, Wi-Fi). That is common and legitimate, but write it in the ad: a candidate expecting a security role who finds they will spend their days on connectivity incidents will not stay.

Scope the role before hiring

Three profiles share the same title. Choose the main focus before writing the ad.

Main focus	What you expect	Typical background	Sign this is your need
Security operations	Manage firewalls, handle flow requests, keep devices up to date	Network administrator, managed services technician	Requests pile up and nobody cleans up the rules
Engineering and projects	Design a new segmentation, migrate a firewall estate, deploy network access control	Experienced network engineer, integrator	A major project is planned within the year
Network detection and response	Use logs and sensors, support investigations	SOC analyst, security-minded network engineer	The SOC lacks visibility into internal traffic

If your need is mostly about design choices across the whole estate (identity, cloud, applications and network together), you are probably looking for a security architect. If your critical flows run mainly through AWS, Azure or GCP, our guide to hiring a cloud security engineer will be more relevant. And for an industrial environment, the constraints are different enough to justify an OT security engineer.

Also be explicit about what weighs on candidates' decisions: on-call duty, night or weekend maintenance windows, site visits, how much remote work is possible. These are sensitive topics in this job, because many network changes happen outside business hours.

The technical skills to check

Networking fundamentals

You can only secure what you understand. The candidate should master the TCP/IP model, routing, VLANs, NAT, DNS and how common protocols work. A network security engineer who hesitates over the difference between stateful and stateless filtering, or cannot read a packet capture, will struggle to diagnose anything.

Filtering and segmentation

This is the heart of the role. Check that they can:

build a readable filtering policy based on "everything not explicitly allowed is denied";
split a network into zones according to asset sensitivity, and justify that split;
isolate administration traffic, in line with ANSSI's recommendations on secure administration of information systems;
audit an existing rule set and spot rules that are too broad, redundant or orphaned.

Remote access and authentication

VPN access, contractor access, strong authentication, service accounts on devices: these are often the attackers' way in. The candidate should be able to explain how they limit a contractor's rights to what is needed, and how they make sure unused access is removed.

Visibility and detection

A good network security engineer thinks about what you will see during an incident. They know which logs to enable on their devices, how to send them to the SIEM and how to help an analyst reconstruct lateral movement. Here the role overlaps with that of the detection engineer.

Automation

Large firewall estates can no longer be managed by hand. The ability to write scripts, use device APIs or configuration management tools is a real asset, even if the role does not call for a developer.

Vendor knowledge

It matters, but less than people think. A candidate who is strong on one vendor picks up another quickly. Ask for real command of a technology close to yours rather than the exact list of your devices.

The qualities that make the difference

Rigour. A misplaced rule can cut a critical service or open a gap. The candidate should have reflexes for checking, documenting and rolling back.
A sense of trade-offs. Every week they receive urgent opening requests. They must be able to say no, offer an alternative and accept a controlled exception when it is justified.
Working with other teams. Developers, system administrators, contractors: they work with everyone. An engineer who blocks without explaining ends up being bypassed.
Thinking like an attacker. The best candidates can look at their own network the way an attacker would: which paths lead to critical assets, what a compromised machine would give access to.

Assess through practice

Vendor network certifications show commitment and product knowledge, but they do not tell you how a candidate reasons about a real network. Our article on certifications in hiring explains how to read them. Beyond that, a hands-on exercise tells you far more.

An effective process fits in four steps:

A first conversation about background, the size of networks managed, the equipment used and the preferred focus.
A time-boxed practical exercise on a test environment, never on your production: a firewall rule set to audit, a network diagram to segment, or a packet capture to analyse.
A peer review: the candidate presents their choices, what they left aside and how they would have rolled out the change in production.
A final conversation with the manager about organisation, on-call duty and career prospects.

If nobody in-house can run the technical interview, our guide to structuring a technical interview without being an expert gives you a method.

Useful questions for the peer review

"You inherit a firewall with several hundred rules and no documentation. Where do you start?"
"A team asks for an urgent flow opening for a release going live tonight. How do you respond?"
"How would you give a contractor access to a single server, for a limited time?"
"The SOC suspects lateral movement between two zones. What information can you give them, and how quickly?"
"Tell me about a network change that went wrong. What did you learn?"

Score answers on a shared grid built before the interviews. Our guide to assessing cybersecurity skills explains how to build one.

Mistakes to avoid

Hiring a network administrator and calling them a security engineer. If the role is mostly network operations, say so. Otherwise the security-minded candidate will leave, and the network-minded one will feel judged on vague expectations.
Demanding an exact vendor list. You rule out strong profiles over a user interface.
Overlooking writing. Flow documentation, change records, incident reports: an engineer who does not write leaves behind a network nobody understands.
Ruling out career changers. An experienced network administrator who has trained in security often becomes an excellent network security engineer. Our guide to hiring career changers explains how to assess that potential.
Keeping quiet about working hours. Night work and on-call duty should be announced and clearly compensated from the first conversation.

In short

To hire a network security engineer, first choose the main focus of the role (operations, projects or detection) and be transparent about working hours. Check networking fundamentals, filtering and segmentation, remote access management and the ability to make the network visible to the SOC. Assess with a realistic exercise followed by a peer discussion, and give rigour and communication as much weight as technical skill.

Looking for a network security engineer and want to avoid a costly mismatch? At Cyber Recrut, a recruiter and a security practitioner scope the need with you, then our shortlisted candidates prove their skills on hands-on labs close to your environment. See how we work or share your hiring need.