Command Line Tools

Question 1

ping - Test reachability

Answer 1

• 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

• 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 - Lookup information from DNS servers

Answer 3

• nslookup

* dig

Question 4

ipconfig and ifconfig - View and manage IP configuration

Answer 4

• 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 - Packet filtering

Answer 5

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

Question 6

netstat - Display network statistics

Answer 6

• 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

Answer 8

• 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 - View the device’s routing table

Answer 10

• route print - View the Windows routing table

Question 11

arp - Address resolution protocol information

Answer 11

• arp -a - View the local ARP table