ECE 4110 Lab Notes: Ping, Traceroute, RARP, Bootp, DHCP, Study notes of Electrical and Electronics Engineering

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ECE 4110

Monday, Nov 18th

Ping, Traceroute

Ping: ICMP based

• Echo request – Echo reply

Traceroute:

• Uses TTL (on a bogus UDP packet)
  • TTL decremented by each router • When TTL reaches zero, packet is deleted,
    • ICMP message TTL expired sent to source
      • Source sends packet with TTL 0,1,2,3…
        • Notes the source of the ICMP message

Reading

• TCP/IP Illustrated, chptrs 6,

Who am I?

• Finding your IP address

• Useful for
  • Out-of-the-box autoconfiguration • Diskless devices • Portables (mobile)
    • RARP
      • Reverse-arp
        • Broadcast your media (ethernet) address – Server replies (unicast) with IP address

RARP

• Uses ARP packet format (not an IP packet) • Limitations:

• Only responds with IP address, – Unknown:
  • Netmask • Gateway/router • DNS server

Bootp limitations

• Hardware (Ethernet) address MUST be pre-

configured into server

• One-to-One Ethernet<-> IP address

correlation

• Cannot “temporarily” assign an IP address

Dynamic Host Configuration

Protocol (DHCP)

Very similar to bootp

• Same ports – Very similar packet – DHCP server can “answer” a bootp request

Adds idea of address “lease”

• Address is only good for limited time – Client can request a renewal of lease – Client hardware address not strictly required to obtain lease (administrator can require this) - Can have statically assigned (reserved) addresses