icmp internet control meessage protocol
ip fragments and routes data
csma/cd carrier-sense, multiple access/carrier detect
utp unshielded twisted pair
10baseT 1 UTP
100baseT4 2 UTP
100baseTX 4 UTP
100baseFX 2 strands of multimode fiber
ethernet addr. administered by Xerox, handed out in triplets 8:0:20 for sun
brdcast addr all ff's, or ones in decimal
mtu maximum transfer unit
arp address resolution protocol, used for assmbly of headers


snoop, netstat, ifconfig

snoop broadcast  
snoop -V mochabomb
netstat -i      Address field: /etc/inet/hosts
netstat -r      display routing table for a local system
ifconfig le0    show info for my interface

ARP TABLE
Entries: device (le0, etc), IP, Mask, flags, Ether addr
ARP table flags: SPMU: saved, published, mapped for multicast, unresolved

example#   arp -a, 
example#  arp -s mochabomb 8:0:20:ab:12:3f      add mochabomb perm'ly to table
example#  arp -s mochabomb 8:0:20:ab:12:3f temp   add mochabomb temp'ly to table: 3-4 minutes
example#  arp -s mochabomb 8:0:20:ab:12:3f pub    use for machines that cannot resp'd to arp req's
example#  arp -d mochabomb                      delete from table
example#  arp -f newhosts.txt              add from a file of form:hostname ether_addr [temp][pub]

NETWORK INTERFACE CONFIGURATION

init process:  /sbin/init   /etc/inittab
/etc/initd/rootusr
/etc/hostname.le0       hostname entry here
arp                     begins with IP, gets ether (target hardware address)
rarp                    begins with known ether, gets IP
snoop -v rarp           see a rarp request, ON SAME SUBNET
in.rarpd                rarp daemon, booting machine must be listed in /etc/iniet/hosts & /etc/ethers
/sbin/ifconfig          -plumb, -a, -unplumb, uses /etc/rc2.d/S72inetsvc & rcS.d/S30rootusr scripts
ifconfig le0 up, down   turn up, down an interface, take it down before tweaking something
ifconfig le0 netmask 255.255.255.0 broadcast + up       guess....

The Internet Layer Class
127.0.0.1 loopback address
A 0 first bit 0 allow 1-127 for class A
B 10[000000 to [111111] first two bits are 10, leaving 128-191 for class B
C 110 first 3 bits are 110, leavinbg 192-223 for class C
D 1110 " " leaving 224-239 for multicast


Netmasks Compute the network number 1 bits keep, 0's mask out

A 255.0.0.0, ff:0:0:0
B 255.255.0.0 ff:ff:0:0
C 255.255.255.0 ff:ff:ff:0


Reserved Numbers
129.146.0.0 network number
129.146.255.255 boardcast on that network
0.0.0.0 IP for 'ignorant' systems, need to boot w/o an IP
255.255.255.255 generic broadcast


IPv6: 128 bit address, versus 32 bit

::192.146.52.26 IPv4 in IPv6 format, :: mean zero.