Transcript CSCE 790: Computer Network Security

CSCE 515:
Computer Network Programming
Chin-Tser Huang
[email protected]
University of South Carolina
Internet Protocol (IP)
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Workhorse of TCP/IP protocol suite
Upper layer data (TCP, UDP, ICMP,
IGMP, etc.) are transmitted as IP
datagrams
Provide unreliable and connectionless
datagram delivery service
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IP Header
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IP Demultiplexing
TCP
ICMP
UDP
IGMP
IP
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IP Options
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A variable-length list of optional information
for the datagram
Always end on 32-bit boundary
Options defined in IPv4 include
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Security and handling restrictions
Record route
Timestamp
Loose source routing
Strict source routing
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IP Routing
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Done on a hop-by-hop basis
If destination is directly connected or on
a shared network, send IP datagram
directly to destination
Otherwise send datagram to a default
router
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Routing Table
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Each entry contains following
information
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Destination IP address
IP address of next-hop router
Flags
Specification of network interface
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Subnet Addressing
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Class B
To make better use of class A and class B
addresses, divide host ID into subnet ID and
host ID
1 0
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netid
1 0
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netid
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hostid
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subnetid
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hostid
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Subnet Mask
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32-bit value containing “1” bits for network ID
and subnet ID, and “0” bits for host ID
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netid
1 0
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subnetid
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hostid
1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 =0xffffff00
=255.255.255.0
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ifconfig Command
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Available at /usr/sbin
Configure or query a network interface
used by TCP/IP
Support address families other than IP
address
-a option to display report of all
interfaces
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netstat Command
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Available at /usr/bin
Display network status
-a option to display state of all sockets, all
routing table entries, or all interfaces
-i option to display interface information
-n option to print IP addresses instead of
host names
-r option to display routing table
-M option to display multicast routing table
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Problems with Current IP
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32-bit IP addresses are inadequate for
Internet growth
Limited support for extensions and
options
Lack of security features
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Future of IP: IPv6
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Designed to be successor of IPv4
Specified in RFC 1883
Five major changes from IPv4
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Expanded Addressing Capabilities
Header Format Simplification
Improved Support for Extensions and Options
Flow Labeling Capability
Authentication and Privacy Capabilities
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IPv6 Header
0
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IPv6 Extension Headers
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Next Class
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ICMP
Ping and traceroute
Routing principles
Read TI Ch. 6, 7, 8, 9
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