LPIC-1: Network Packets and IP Command

Network Troubleshooting Tools

• Hex viewers and protocol analyzers can be used to view packets in more detail than a packet sniffer.

The ip Command

• The ip command is a utility used to view and configure network configurations.
• Each subcommand of ip has its own man page.
• The SEE ALSO section of the ip man page lists available subcommands.

Internet Control Message Protocol (ICMP)

• ICMP is a network layer protocol in the TCP/IP stack.
• ICMP is used for traffic volume control, detection of unreachable destinations, route redirection, and checking the status of remote hosts.
• ICMP is used by the ping command.

IPv6

• IPv6 is the new version of the IP protocol, with a 128-bit address divided into 8 groups of 16 bits.
• IPv6 addresses can be abbreviated by reducing strings of 0000 to 0 and omitting strings with a value of 0.
• IPv6 addresses can be shortened, but this can only be done once in the address.

Configuring Network Interfaces

• The ip command can be used to configure network interfaces.
• The link subcommand for ip lists the interface links available for configuration.
• The ip addr subcommand is used to view and configure IP addresses.
• The ifconfig command can also be used to configure network interfaces, but it requires root privilege.

Listing Network Interfaces

• The ip link command lists the interface links available for configuration.
• The /sys/class/net directory can also be used to list network interfaces.