- **Linux**: RHEL/Debian/Ubuntu, kickstart, PXE, LDAP, SSSD, RPM/Deb package creation, quotas, extended permissions, clustering , AppArmor, SeLinux, Centrify, Tripwire, Integrit, OSSEC. 22 years
- **Unix**: HPUX/Solaris 5 years
- **Windows**: Server (2008 - 2016), Windows client automated deployment (7,8,10,11), Active Directory, Group Policy, WSUS, Certificate Services, AD DNS, AD DHCP, complex multiple forest and domain setups, LDAP. 22 years
- **/Free/Libre/Open Source Server software**: Apache, Postfix, Qmail, Dovecot, Courier, Nginx, Matamo, Discourse, Wordpress, Mautic,Dolibarr, Revive, Firefly, Cloudron, Coolify, Gitea, Gitlab, GitHub, Git, Jenkins, Rundeck, N8N, Mysql,Postgresql,  LetsEncrypt, ACME, cfssl. 22 years.
- **Security**: PCI Compliance, security hardening,audits, breach response and mitigation, patch and vulnerability management. 22 years
- **Networking**: Linux Virtual Server, HAProxy, Ubiquiti Unifi, Opnsense, Pfsense, HP, Cisco, Arista, Dell, DNS, DHCP, IPAM, PXE, IPS, IDS, GRE, IPSEC. Wireguard, OpenVPN, Nebula, Tailscale, RADIUS. Mostly layer2 data center/campus/access some WAN,firewall,layer3. 22 years
- **Monitoring**: Uptime kuma, librenms, zabbix, zenoss, nagios 22 years
- **Storage**: NFS, Samba, CIFS, Netapp, ZFS, True/Free NAS, 3par, MSA, Equallogic, EMC, generic iscsi. 22 years
- **Virtualization**: VmWare, Parallels,HyperV, KVM, Xen. 22 years.
- **Containerization**: LXC, Docker, Compose.  12 years
- **Configuration management**: Slack, Cfengine, Puppet, FetchApply, Ansible, Hashicorp Packer/Vault (20 years)
- **Embedded**: Raspberry pi, arduino, seeduino, Lego Mindstorms , 5 years.
- **Programming/Automation**: Bash , J2ME, PHP, Ruby, PowerShell, TCL/TK, Java. 10!years.
- **Ticket / incident / project management**: Jira, ServiceNow,Redmine,RT. 20 years.
- **Git**: branching, merging, multiple teams, external vendors, submodules etc. 15 years
- **Current growth/learning focus**: Prometheus, Grafana, CI/CD, GCP, AWS, Azure, Kubernetes, Helm (2 year in dev labs)