Category
TCP/IP
TCP, UDP, and IP headers, flags, port and protocol references, MSS and MTU math.
ICMP & ICMPv6 Type/Code Reference
Searchable reference of ICMP (IPv4) and ICMPv6 message type and code values, with the ICMPv6 error vs informational split and a type/code lookup.
IP Protocol Numbers
Searchable reference of IP protocol numbers — the IPv4 Protocol field and IPv6 Next Header field — with IPv6 extension-header flagging.
IPv4 Header Decoder
Decode a raw IPv4 header from hex — version, IHL, DSCP/ECN, flags, fragment offset, TTL, protocol, addresses — and verify the header checksum. Decode only; nothing is sent anywhere.
MTU/MSS Calculator
Derive the advertised TCP MSS from a path MTU, or plan a tunnel MTU from an underlay link, keeping L2 framing, encapsulation and TCP options apart.
TCP Flags Decoder/Encoder
Decode and encode TCP control bits—SYN, ACK, FIN, RST, PSH, URG, ECE, CWR—with hex, decimal, and binary representations.
Well-Known Port Reference
Searchable quick-reference of common TCP and UDP port assignments, with IANA range classification for any port number.