Terminal Commands

Question 1

ping

Answer 1

Ping tests reachability.

• ping - Test reachability to a TCP/IP address
• ping -t - Ping until stopped with Ctrl-c
• ping -a - Resolve address to a hostname
• ping -n - Send # of echo requests
• ping -f - Send with Don’t Fragment flag set

Question 2

traceroute

Answer 2

Traceroute determines the route a packet takes to a destination.

• Takes advantage of ICMP Time to Live Exceeded error message
• Not all devices will reply with ICMP Time Exceeded messages
• traceroute

Question 3

nslookup and dig

Answer 3

nslookup and dig lookup information from DNS servers.

• nslookup
• dig

Question 4

ipconfig and ifconfig

Answer 4

ipconfig and ifconfig - View and manage IP configuration.

• ipconfig - Windows TCP/IP config
• ipconfig /all - Display all IP configuration details
• ipconfig /release - Release the DHCP lease
• ipconfig /renew - Renew the DHCP lease
• ipconfig /flushdns - Flush the DNS resolver cache
• ifconfig - Linux interface configuration

Question 5

iptables

Answer 5

iptables - Packet filtering

• Linux iptables - filter packets in the kernel
• Simple data blocks - ignores state
• Usually placed on a device or server

Question 6

netstat

Answer 6

netstat displays network statistics.

• netstat -a - Show all active connections
• netstat -b - Show binaries
• netstat -n - Do not resolve names

Question 7

tcpdump

Answer 7

• Capture packets from the command line
• Available in most Unix/Linux operating systems
• Included with Mac OS X,
available for Windows (WinDump)
• Apply filters, view in real-time
• Written in standard pcap format

Question 8

pathping - Combination of ping and traceroute

Answer 8

pathping is a combination of ping and traceroute.

• pathping

Question 9

Nmap

Answer 9

• Network mapper - find network devices
• Port scan - Find devices and identify open ports
• Operating system scan
• Discover the OS without logging in to a device
• Service scan
• What service is available on a device?
Name, version, details
• Additional scripts
• Nmap Scripting Engine (NSE)

Question 10

route

Answer 10

route - View the device’s routing table.

Question 11

arp

Answer 11

arp - Address resolution protocol information.

• arp -a - View the local ARP table