Tasks

How Internet Works

Internal Network

  1. The packet goes from device 44:55:66 to the switch.

  2. The switch will extract from layer 2 the mac address.

  3. The switch will check its CAM table and forward the packet to Device dd:ee:ff.

External Network

  1. The packet goes from device 44:55:66 to the switch.

  2. The switch will extract from layer 2 the mac address.

  3. The switch will check its CAM table and forward the packet to the router.

  4. The router will extract from layer 3 the destination IP address.

  5. The router will check its routing table and forward the packet to the next node.

  6. The packet now has the source IP of the router's external IP.

  7. Now the routing process will take place until arrived at the final node before the destination.

  8. The final node will extract from layer 3 the destination IP address.

  9. The router will check its routing table and forward the packet to the final node (destination).

  10. The destination will receive the packet and extract from it the source IP and the data.

From Ethernet To Google.com

  1. DHCP Discover.

  2. DHCP Offer.

  3. DHCP Request.

  4. DHCP ACK.

  5. ARP broadcast looking for the default gateway.

  6. ARP unicast reply providing the MAC address of the gateway.

  7. DNS A (IPv4) forward lookup query for google.com

  8. DNS AAAA (IPv6) forward lookup query for google.com

  9. DNS A response received.

  10. DNS AAAA response received.

  11. A 3-way handshake with port 80 on google.com

  12. Initial protocol negotiation in HTTP, GET request sent.

Wireshark Filters

ip.addr == x.x.x.x
ip.src == x.x.x.x && ip.dst == x.x.x.x
http or dns
tcp.port == xxx
udp.port == xxx
tcp contains xx8x
tcp.stream eq X
http.request && tcp
!(arp or icmp or dns)
dns.resp.name
dns && !dns.resp.name
PreviousBasicsNextProgramming

Last updated