68 Bootstrap Protocol Client - System Port

68 is a System Port. Transport Protocol TCP UDP , 68 Service Name bootpc, Service Name Description: Bootstrap Protocol Client.

Port	Protocol	Service Name	Description	Source
68	TCP UDP	bootpc	Bootstrap Protocol Client	IANA
68	UDP		Bootstrap Protocol (BOOTP) Client; also used by Dynamic Host Configuration Protocol (DHCP),Official	wikipedia
68	UDP		Bootstrap Protocol Client (bootpc), NetBoot via DHCP	Apple.com
68	TCP UDP	bootpc	Bootstrap Protocol Client	bekkoame

Port	Service Name	Description
1637	islc	ISP shared local data control
2624	aria	Aria
2765	qip-audup	qip-audup
3087	asoki-sma	Asoki SMA
4361		Reserved
4678	traversal	boundary traversal
6347	gnutella-rtr	gnutella-rtr
6390	metaedit-ws	MetaEdit+ WebService API
7302	swx	The Swiss Exchange
7960		Unassigned

A port is an endpoint of communication in an operating system. While the term is also used for hardware devices, in software it is a logical construct that identifies a specific process or a type of service.

Port numbers are assigned in various ways, based on three ranges: System Ports (0-1023), User Ports (1024-49151), and the Dynamic and/or Private Ports (49152-65535);

The Well Known Ports are assigned by the IANA and on most systems can only be used by system (or root) processes or by programs executed by privileged users. Ports are used in the TCP [RFC793] to name the ends of logical connections which carry long term conversations. For the purpose of providing services to unknown callers, a service contact port is defined. This list specifies the port used by the server process as its contact port. The contact port is sometimes called the "well-known port". To the extent possible, these same port assignments are used with the UDP [RFC768]. The range for well-known ports managed by the IANA is 0-1023.
DYNAMIC AND/OR PRIVATE PORTS Registered Ports are those from 1024 through 49151.
The Dynamic and/or Private Ports are those from 49152 through 65535