__Networking

Networking

• Networking Fundamentals: https://www.youtube.com/watch?v=bj-Yfakjllc&list=PLIFyRwBY_4bRLmKfP1KnZA6rZbRHtxmXi
• https://www.reddit.com/r/devops/comments/rpspmu/how_did_you_guys_learn_networking/
• https://lucidmentor.com/networking/
• LAN, peer to peer network
  • WAN
  • Domain Network
• firewall and its working
• broadcast address (0 vs 255), muticast, anycast, unicast
  • https://serverfault.com/questions/279482/what-is-the-difference-between-unicast-anycast-broadcast-and-multicast-traffic
• Wireshark, Promiscuous mode, monitor mode

Network

• Networks is what transports traffic between hosts
• Logical grouping of hosts which require similar connectivity
• Networks can contain other networks
  • These are sometimes called sub-networks or subnet
• Networks connect to other networks

Network Protocols

• A network protocol is a set of rules that allows for data transmissions across different technologies.

Protocols

• ARP - Address Resolution Protocol
• FTP - File Transfer Protocol
• SMTP - Simple Mail Transfer Protocol
• HTTP - Hyper Text Transfer Protocol
• TLS - Transport Layer Security
• SSL - Secure Sockets Layer
• HTTPS - HTTP Secured with TLS/SSL
• DNS - Domain Name System
• DHCP - Dynamic Host Configuration Protocol

Commands

• https://www.windowscentral.com/8-networking-command-tools-every-user-should-know-windows-10
• nmap
• nslookup
• netstat
• ping
• traceroute/tracert
• cat /etc/hosts
• route
• netsh
• lsof
• arp
• ipconfig/ifconfig

ping

• uses ICMP protocol
• send 10 packets
  • shows % packet loss also

ping <ip> -n 10

traceroute

• print the route packets take to network host

traceroute example.com

tracert

• Available on Windows
• shows hops
• Uses ICMP Time to Live (TTL)
• If stars are in output then, device used in particular hop is not configured to reply to ICMP and UDP traffic
  • does not mean that the traffic was not passed successfully

tracert <ip>
 
# check google DNS
tracert 8.8.8.8
 
# google website
tracert www.google.com

route

• Manually manipulate the network routing tables

netsh

• Available on Windows
• Check the current Wifi standard

netsh wlan show interfaces

lsof

• LiSt Open Files
• Check the process on port

lsof -i:8080

• Check all open ports

sudo lsof -PiTCP -sTCP:LISTEN

nmap

• Network Mapper
• Network exploration tool and security / port scanner

nslookup

• Query Internet name servers interactively

# --- Interactive Mode ---
nslookup
 
## Check for google.com
> google.com
Server:		10.119.64.1
Address:	10.119.64.1#53
 
Non-authoritative answer:
Name:	google.com
Address: 142.250.194.174
 
# --- Non-Interactive Mode ---
 
## Check for example.com
nslookup example.com
 
## Check for example.com on 8.8.8.8 DNS Server
nslookup example.com 8.8.8.8

netstat

• Show network status
• Displays the contents of various network-related data structures

arp

• Displays and modifies the Internet-to-Ethernet address translation tables (ARP Cache) used by the ARP protocol

# Show arp cache
arp -a