Lesson 4

Dates: 2/12/2014
Linux networking
Linux for Engineering and IT Applications


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

    Example: traceroute 
    /usr/sbin/traceroute -I eden.rutgers.edu
traceroute to eden.rutgers.edu (128.6.68.10), 30 hops max, 60 byte packets
 1  capone (192.168.5.240)  0.160 ms  0.158 ms  0.156 ms
 2  vlan102-ar01-eng-hill.runet.rutgers.net (128.6.238.65)  0.503 ms  0.573 ms  0.630 ms
 3  gigabitethernet1-5-dr01-hill-bus.runet.rutgers.net (172.28.6.22)  0.616 ms  0.684 ms  0.760 ms
 4  tengigabitethernet1-4-cr01-hill-nbp.runet.rutgers.net (172.28.194.2)  0.759 ms  1.057 ms  1.130 ms
 5  tengigabitethernet5-4-sr01-hill-nbp.runet.rutgers.net (172.28.193.133)  0.911 ms  0.985 ms  1.047 ms
 6  eden-in.rutgers.edu (128.6.68.10)  0.425 ms  0.322 ms  0.312 ms
    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.

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