AD · patching · builds
Windows Server
Installation, configuration and ongoing maintenance; Active Directory for secure authentication, authorisation and central management; and patch management that keeps systems current rather than a year behind.
Windows · Linux · Microsoft 365 · identity
System administration services
The work nobody notices until it stops happening. We administer your Windows and Linux servers, Microsoft 365 tenancy and identity platform so your team can focus on the business.
What we administer
The four platforms every business runs on
System administration is the work nobody notices until it stops happening. We handle Windows, Linux, Microsoft 365 and identity so your team can get on with the business.
RHEL · Ubuntu · CentOS
Linux
Server configuration tailored to your workloads, security hardening against real threat models rather than a generic checklist, and performance tuning with monitoring so problems surface before users report them.
Exchange · Teams · licensing
Microsoft 365
Exchange Online administration, getting genuine value from Teams, SharePoint and OneDrive, and licence management that stops you paying for seats and tiers nobody uses.
RBAC · joiners & leavers
Identity & access
Role-based access control so sensitive systems are reachable only by those who need them, account provisioning from onboarding through offboarding, and password policy backed by regular audits.
Coverage
Operating systems and directories we support
Current releases and the legacy estate you have not been able to retire yet — both need administering, and only one of them is interesting.
Windows & directory
- Windows Server 2016 – 2022
- Windows Server 2012 and below
- Active Directory
- Entra ID
- Group Policy
Linux & UNIX
- RHEL & CentOS
- Ubuntu
- Oracle Linux
- Solaris & AIX
- HP-UX
Identity & web services
- LDAP & Keycloak
- Nginx & HAProxy
- Apache & Tomcat
- Microsoft 365
Typical work
What clients actually ask us to do
Some of it is scheduled, some of it lands on a Friday afternoon. Both are covered.
- Build, configure and commission new servers
- Run the monthly patch cycle across servers and workstations
- Active Directory health, cleanup and domain migrations
- Onboard and offboard staff, with access revoked the same day
- Harden a server before it faces the internet
- Diagnose why a system has become slow and fix the cause
- Review Microsoft 365 licensing and cut what is not used
- Implement RBAC and tighten password policy after an audit finding
Why Onsys
Why hand this over
Expertise
Extensive experience across Windows, Linux, UNIX and Microsoft 365 — the estate administered by specialists, not by whoever is free.
Reliability
Your infrastructure kept secure and available, with patching and monitoring that happen on schedule rather than when someone remembers.
Custom solutions
Services aligned to your organisation’s actual needs and constraints, not a fixed package you have to bend your environment around.
Ready to optimise and secure your infrastructure?
Tell us what you run and where the gaps are. A senior consultant will come back with an honest assessment and what it would take to close them — free.
Talk to a ConsultantPublished
FAQ
Common questions
Hourly system administration is $150 per hour with a four-hour minimum, GST exclusive. It is also included within managed IT plans from $4,500 per month, and defined work such as a domain migration can be quoted as a fixed price.
Windows Server 2012 through 2022, Linux including RHEL, CentOS, Ubuntu and Oracle Linux, and UNIX platforms including Solaris, AIX and HP-UX. We also administer Active Directory, Entra ID, LDAP, Keycloak, Nginx, HAProxy, Apache and Tomcat.
Yes — Exchange Online administration, Teams, SharePoint and OneDrive configuration, and licence management. Licence reviews frequently pay for themselves by identifying seats and tiers that are paid for but not used.
Yes. We run the monthly patch cycle across servers and workstations on a defined schedule, so systems stay current rather than falling a year behind and becoming an audit finding.
Yes. Account provisioning covers the full lifecycle from onboarding to offboarding, with access revoked the same day someone leaves — the step most often missed and the one that matters most.
Yes. Security hardening covers Linux and Windows builds facing the internet, implementing role-based access control, tightening password policy, and auditing the result rather than assuming the change took effect.
Yes. Changes needing a maintenance window can be scheduled after hours or at weekends, billed at the same $150 per hour against actual time worked.
Yes, and it usually is. Most clients fold it into a managed IT plan alongside network, endpoint and Microsoft 365 support, so there is one supplier and one escalation path rather than several.