Agent and Agentless Deployments
Software on the target or nothing on the target. The trade-off affects coverage, operational burden and what an administrator can evade.
Reference
The deployment model is one of the first decisions and it constrains everything afterwards.
Agentless
Nothing installed on the target. Control happens at the broker or the network.
Advantages: no deployment or maintenance burden; works on appliances and closed systems; nothing on the target for an administrator to disable; faster to roll out broadly.
Limitations: only sees what passes through the broker; cannot capture console or local access; cannot enforce anything on the target itself; depends entirely on the path being enforced.
The right default for breadth, and it makes path enforcement the critical control.
Agent-based
Software on the target captures and enforces locally.
Advantages: captures activity regardless of how the session started, including console; can enforce elevation policy locally; can work when the broker is unreachable; sees process-level detail.
Limitations: deployment and lifecycle burden across the estate; impossible on appliances; an administrator on the target may be able to interfere with it; another agent competing for endpoint resources and another supply chain dependency.
The right choice where local enforcement matters, particularly workstation privilege elevation.
Where each fits
Server session brokering: agentless, with the path enforced.
Workstation privilege elevation: agent, because there is no session to broker.
Unix elevation policy: agent, replacing or wrapping the local elevation mechanism.
Appliances and network devices: agentless, necessarily.
Cloud: neither, in the traditional sense — the platform's own audit and role mechanisms are the control.
Most estates need both, and treating it as a single choice is the error.
The path enforcement requirement
Agentless deployments live or die on this.
Network restriction so management interfaces are reachable only from the broker.
Host-level logon restrictions by source.
Firewall rules that a server administrator cannot alter, which means they are enforced elsewhere.
Detection of sessions established outside the path, from target-side authentication logs.
Without enforcement, agentless PAM is optional, and the administrators who find it slow will opt out.
The agent burden
Worth costing honestly before choosing.
Deployment to the whole estate.
Version management and the compatibility matrix with operating systems.
Failure handling: what happens when the agent is down — fail open or fail closed, decided deliberately.
Performance impact, measured rather than assumed.
Interaction with other endpoint agents, which is a real source of incidents.
A dependency on the vendor for every operating system you run, including the old ones.
The hybrid reality
Most mature deployments run agentless brokering for servers, agents for workstation elevation, native controls in cloud, and target-side logging everywhere as a backstop.
Four mechanisms, one inventory, one ownership model.
Report coverage per mechanism, because a single coverage figure across all of them conceals which parts of the estate are actually controlled.
Costing the agent properly
The burden appears in year two and is rarely in the business case.
Deployment across the estate, including the machines nobody manages well.
Version compatibility with every operating system you run, including the old ones the vendor may drop.
Failure handling, decided per tier.
Performance impact, measured on a representative workload rather than accepted from a datasheet.
Interaction with other endpoint agents, which is a genuine source of incidents and is only discovered in production.
A permanent dependency on the vendor for platform support, which constrains your own upgrade schedule.
Reporting coverage per mechanism
A single coverage figure across mixed mechanisms conceals which parts of the estate are actually controlled.
Brokered server sessions: proportion of privileged authentications through the broker.
Workstation elevation: proportion of endpoints with the agent healthy and reporting.
Unix elevation: proportion of hosts with managed policy.
Cloud: proportion of accounts with audit logging enabled and shipped.
Report separately, with the denominator stated for each.
The weakest number is the programme's real coverage, because an attacker uses the weakest path rather than the average one.