Networking Notes
November 3, 2005
ISO network model, layering
IP addressing

    ifconfig

datagram delivery (UDP)
ports to specify services
Ports: well-known ports, port sniffers
reliable streams - notecard experiment
TCP
packet sniffing

    sudo tcpdump -i en0               for wired ethernet
    sudo tcpdump -i en1               for wireless

Sending mail: SMTP - http://www.ietf.org/rfc/rfc0821.txt (port 25)

    telnet <smtp-server> 25
    HELO <sending-server>
    MAIL FROM:<reverse-path> <CRLF>
    RCPT TO:<forward-path> <CRLF>
    DATA <CRLF>
    . <CRLF>
    QUIT <CRLF>

Name lookup with DNS

    dig bennington.edu
    dig -x 12.16.115.8

pairNIC demo
Service discovery with Rendezvous
Security - encryption

Aside:
“infinite loop” - http://www.apple.com/contact/

1962 “Galactic Network”
1969 ARPANET, 4 nodes
1972 email invented (name@computer)
1973 ftp invented
1975 leaves ARPA
1976 Queen Elizabeth II sent the first royal email
1983 TCP/IP principal protocol of the internet
1983 telnet invented
1989 HTML invented, other browsers in 1992
today, hundreds of millions of computers with IP addresses

Growth:
1969 4 nodes in SF area
1970 cross-continent
1973 40 nodes across US
1973 satellite links to Hawaii and Norway; Norway to London
1977 136 nodes (according to ARPANET map)
1981 200 nodes