Networking 101

Computer networking basics for IT professionals

19 December 2018

Tiago "Myhro" Ilieve

DevOps Engineer, Zalando SE

OSI Model

1. Physical layer (Modem/DSL, Wi-Fi, Hubs)
2. Data link layer (Ethernet, PPP, Switches)
3. Network layer (IP, ICMP)
4. Transport layer (TCP, UDP)
5 and 6. Nobody cares
7. Application layer (HTTP)

Deeper look at transport protocols

Ports
Headers
TCP vs. UDP: * Reliability * Connections * Sequencing * ACKs * Retransmissions
TCP-over-TCP (and more)

Debugging

Basic connectivity (caveat lector!): ping
Routes: route (net-tools), ip (iproute2)
Routing: traceroute, mtr
DNS: dig
TCP/UDP: nc
HTTP: curl
Sockets: netstat (net-tools), ss (iproute2)
Bandwidth: iperf
Traffic: tcpdump

Thank you

Tiago "Myhro" Ilieve

DevOps Engineer, Zalando SE

https://blog.myhro.info/

@myhro

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