Internet Protocol Options; Transfer Protocols - Watchguard Firebox X20E Reference Manual

Internet Protocol options

Internet Protocol options are variable-length additions to the standard IP header. IP
options can either be of limited usefulness or very dangerous. There are several kinds
of IP options:
Security
Control routing of IP packets that carry sensitive data. Security options are
rarely supported.
Stream ID (SID)
The stream ID option is rarely supported.
Source Routing
Both the loose source route option and the strict source route option enable
the source of an Internet packet to provide routing information. Source
routing options can be very dangerous, because a clever attacker might use
them to masquerade as another site. However, loose source routing and the
traceroute facility can also help debug some obscure routing problems.
Record Route
The record route option was originally intended for use in testing the Internet.
Unfortunately, record route can record only ten IP addresses. On the present
Internet, typical long-haul transmissions can involve twenty or thirty hops,
rendering the record route option obsolete.
Time Stamp
The time stamp option helps measure network propagation delays. This task
is done more effectively, however, with higher-level time protocols or time-
stamp messages.
Because most applications make it very obscure or difficult to use IP options, they are
rarely used.

Transfer protocols

The IP protocol encapsulates information contained in the transport layer. The
transport layer has several protocols that specify how to transmit data between
applications: for example, UDP, TCP, ICMP, and others.
UDP
User Datagram Protocol (UDP) is a connectionless, potentially unreliable datagram
protocol. It trades reliability for speed and low overhead. To ensure accurate
transmission, it requires that the application layer verify that packets arrive at their
destination.
Characteristics of UDP include:
Reference Guide
Internet Protocol options
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