Lesson 5

Dates: 6/12/2017
Linux networking
Linux System Administration


Exercise: Internet Control Message Protocol (ICMP) protocol

Implemented on hosts and gateways (routers) for:
  • Reporting the status of datagram processing.
  • Diagnostics of connection and routing.
  • Reporting errors in the processing of a datagram.

  • Example: ping

  • Exercise: command ping.
    ping -c 5 capone
    ping -c 5 eden.rutgers.edu
    ping -c 5 google.com
    
    If the systems respond, it means they are reachable on the network. Notice how varies the round-trip time and Time to Live (ttl) for packets between the hosts.

  • Example: traceroute
    Time to leave (TTL) decrement. The TTL value of an IP packet represents the maximum number of IP routers that the packet can go through before being thrown away. You can expect each router in the Internet to decrement the TTL field by exactly one. The default TTL for traceroute on Linux is 30. It can be increased up to 255 maximum by using the -m command option.

  • Exercise: command traceroute.
    sudo /usr/sbin/traceroute -I capone 
    sudo /usr/sbin/traceroute -I eden.rutgers.edu
    sudo /usr/sbin/traceroute -I google.com 
    
    This shows you all the gateways between the subnets your packet travels towards the destination. Notice the difference in the number of gateways between your desktop and the three remote hosts as well as the round trip times.




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