Protocol Reference tools
Fast lookup tables for ports, protocol numbers, EtherTypes, TCP flags, ICMP types, DHCP options, DNS record types and the command flags you always have to check.
DNS Record Types Reference
Every DNS record type worth knowing, with numeric codes, zone-file syntax examples and the rules that trip people up at the zone apex.
HTTP Status Codes
Searchable HTTP status code reference including the proxy-specific codes - 499, 502, 504, 52x - that actually show up in production incidents.
Linux Network Commands
The modern Linux networking command set - ip, ss, ethtool, tcpdump, nft - with the exact invocations worth memorising.
OSI Model Reference
The seven OSI layers with the protocols, data units and real troubleshooting signals that belong to each, mapped against the TCP/IP model.
Port Number Lookup
Look up what runs on a TCP or UDP port, or find the port for a service - with a note on whether it is safe to expose.
Protocol Numbers, EtherTypes & Flags
IP protocol numbers, Ethernet EtherTypes, ICMP types and TCP flags in one searchable place - the values that appear in ACLs and packet captures.