Network port

Port 25

Port 25 is registered to smtp: Mail submission and relay between servers. It runs over TCP and falls in the system (well-known) range.

Service

Port number25

IANA service namesmtp

Usually runsMail submission and relay between servers

TransportTCP

Encrypted by defaultNotraffic is readable in transit unless the protocol adds its own encryption

IANA rangeSystem (well-known)assigned by IANA; binding needs privilege on Unix

Needs privilege to bindYes on Unixports below 1024 need root or CAP_NET_BIND_SERVICE

Hexadecimal0x0019

Binary0000000000011001

Bits needed5

Highest possible port65,535the field is 16 bits wide

Every link below is a page Nerdulator can generate from what it already knows about this value.