2 cissp ® Official Study Guide Eighth Edition

, UDP Ports 67 and 68
DHCP uses port 67 
as the destination port on the server to receive client communications and port 68 as the 
source port for client requests. It is used to assign TCP/IP configuration settings to systems 
upon bootup. DHCP enables centralized control of network addressing.
Hypertext Transfer Protocol (HTTP)
, TCP Port 80
This is the protocol used to transmit 
web page elements from a web server to web browsers.
Secure Sockets Layer (SSL)
, TCP Port 443 (for HTTP Encryption)
This is a VPN-like 
security protocol that operates at the Transport layer. SSL was originally designed to sup-
port secured web communications (HTTPS) but is capable of securing any Application 
layer protocol communications.

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TCP/IP Model 
463
Line Print Daemon (LPD)
, TCP Port 515
This is a network service that is used to spool 
print jobs and to send print jobs to printers.
X Window
, TCP Ports 6000–6063
This is a GUI API for command-line operating 
systems.
Network File System (NFS)
, TCP Port 2049
This is a network service used to support file 
sharing between dissimilar systems.
Simple Network Management Protocol (SNMP)
, UDP Port 161 (UDP Port 162 for Trap 
Messages)
This is a network service used to collect network health and status information 
by polling monitoring devices from a central monitoring station.
SNmPv3
Simple Network Management Protocol (SNMP) is a standard network-management pro-
tocol supported by most network devices and TCP/IP-compliant hosts. These include 
routers, switches, bridges, wireless access points (WAPs), firewalls, VPN appliances, 
modems, printers, and so on. Through the use of a management console, you can use 
SNMP to interact with various network devices to obtain status information, performance 
data, statistics, and configuration details. Some devices support the modification of con-
figuration settings through SNMP.
Early versions of SNMP relied on plaintext transmission of community strings as authen-
tication. Communities were named collections of network devices that SNMP manage-
ment consoles could interact with. The original default community names were public 
and private. The latest version of SNMP allows for encrypted communications between 
devices and the management console, as well as authentication factors that are custom-
ized for robust authentication protection.
SNMP operates over UDP ports 161 and 162. UDP port 161 is used by the SNMP agent 
(that is, network device) to receive requests, and UDP port 162 is used by the manage-
ment console to receive responses and notifications (also known as 
trap messages
). Trap 
messages inform the management console when an event or threshold violation occurs 
on a monitored system.