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 effective MTU and TCP MSS for GRE, IPSec, VXLAN, WireGuard and PPPoE tunnels. Includes MSS clamping commands.
INTERACTIVEGenerate fabric uplinks, server connections and full patch schedules for spine-leaf DC topologies. Visual topology + Excel export.
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