Fast, free tools for subnetting, CIDR, firewall rules, and VPN configs. Built by a network engineer, for network engineers. No ads, no noise.
Enter any IP and prefix length. Instantly get network address, broadcast, usable host range, wildcard mask, and binary breakdown.
INTERACTIVEComplete /0 through /32 reference. Network mask, wildcard, host count, and typical use cases — all on one fast page.
REFERENCEiptables, pfSense, and Windows Firewall quick-reference rules. Common allow/deny patterns, logging, and NAT examples.
CHEAT SHEETOpenVPN, WireGuard, IPSec, and L2TP compared. Config snippets, port numbers, and use-case guidance for each.
REFERENCEping, traceroute, nmap, tcpdump, netstat, ss, dig — essential one-liners for Linux, Windows and Mac.
CHEAT SHEETComplete searchable TCP/UDP port table. Well-known and registered ports with categories and descriptions.
SEARCHABLEBGP states, path attributes, best-path selection, Cisco and Juniper show commands, OSPF and protocol comparison.
REFERENCETLS versions, cipher suites, OpenSSL commands, certificate chain, common errors and nginx config.
SECURITYInteractive 7-layer reference. Protocols, devices, and attack vectors per layer. Click to expand each layer.
INTERACTIVECat5-Cat8, fiber types, SFP transceivers, connectors, PoE standards and speed/distance tables.
REFERENCECarve subnets from supernets, track IP assignments, manage VLANs. Browser-based, no account needed.
TOOLCalculate overhead for GRE, IPsec, and VXLAN tunnels. Troubleshooting tool for fragmentation issues and optimal MSS clamping values.
INTERACTIVE