1. How to capture tcpdump files and then parse it using stak to get a clear picture how the 
provider-user model works in real environment stack.

1. I used a tool called, wireshark to dump network packet in libpcap(*.pcap) format and fed it into
stak to give me output as Prof. Harris showed.
2. I captured several packet. The simple of them was a ping command. The stack it uses in request and
reply is like: ether-ip-icmp-none. ICMP is Internet Control Message Protocol.
3. The request and response for ping command is like this:

----------------------------------------------------------------------------------
[27.00718.00973](0.00006.00987)   CAPTURE-00020 74/74
PROVIDER:ether USER:ip <14+60>
Available bytes:74
src:00-16-9c-38-78-40 dst:00-1a-73-26-9b-b4 length: 2048
PROVIDER:ip USER:icmp <20+40>
Available bytes:60
4    src:134.48.6.129 dst:10.160.3.71   hlen:20 len:40 tos:0 id:10668 ttl:248 protocol:1 CheckSum:be7c
PROVIDER:icmp USER:none <8+32>
icmpType:Echo Reply icmpCode:0 id:1 seq:6
 length:32
00000000   61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70  abcdefghijklmnop
00000010   71 72 73 74 75 76 77 61 62 63 64 65 66 67 68 69  qrstuvwabcdefghi

[28.00713.00912](0.00994.00939)   CAPTURE-00021 74/74
PROVIDER:ether USER:ip <14+60>
Available bytes:74
src:00-1a-73-26-9b-b4 dst:00-16-9c-38-78-40 length: 2048
PROVIDER:ip USER:icmp <20+40>
Available bytes:60
4    src:10.160.3.71 dst:134.48.6.129   hlen:20 len:40 tos:0 id:27336 ttl:128 protocol:1 CheckSum:3561
PROVIDER:icmp USER:none <8+32>
icmpType:Echo  icmpCode:0 id:1 seq:7
 length:32
00000000   61 62 63 64 65 66 67 68 69 6a 6b 6c 6d 6e 6f 70  abcdefghijklmnop
00000010   71 72 73 74 75 76 77 61 62 63 64 65 66 67 68 69  qrstuvwabcdefghi