Network information & tools
Free tools and guides for everyone who works with networks: subnetting, DNS, certificates, Wi-Fi, routing and the latest CVEs. Everything runs in your browser.
Network diagram
Network Tools
/24Subnet calculatorNetwork, mask, broadcast and host range::/64IPv6 calculatorPrefixes, notation, splitting into /64s, EUI-64 and solicited-nodeVLSMVLSM plannerTurn "Office 120, Guest 50" into a subnet planΣSummarize & overlapAggregate prefixes, find duplicates and overlaps, range to CIDR/31Link netsSplit a range into /31, /30 or /32 pairs/0CIDR tableEvery prefix from /0 to /32
Services
MACMAC vendor lookupFind the vendor behind one address or a whole listDNSDNS lookupA, AAAA, MX, TXT, CAA, PTR and more, via Cloudflare or Google@Email checkSPF, DMARC, DKIM and MTA-STS for a domainX.509Certificate decoderRead certificates, chains and CSRs, and check that the key matches:443PortsTCP and UDP ports and IP protocols, with notes for network gearPCAPWireshark filtersDisplay and capture filters, tshark commands and a filter builder
Firewall
VPN
Routing
Switching
L2Layer 2 explainedMAC addresses, switching, VLANs, trunks and Spanning Tree for beginners01:00Multicast IP ↔ MACThe MAC address of a group, and which groups share it224Multicast groupsWhat a multicast address is used for, and how far it reaches
Wi-Fi
CHChannel plannerChannels on 2.4, 5 and 6 GHz, with a plan per access pointMb/sThroughputTheoretical and realistic speed for Wi-Fi 5, 6 and 7802Wi-Fi standardsWi-Fi 5, 6, 6E, 7 and 8 explained simply