ifconfig -l (—list)

• ifconfig = Netwrok Interface Configurator

a. ifconfig en0

• en0 = ethernet interface

b. arp -a

• arp = Address resolution display and control

  • displays IP addresses connected to same local network
  • uses ARP cache?

• sed -e ‘s/.255//g’

  <aside> 💡 Substitution command

  In some versions of sed, the expression must be preceded by -e to indicate that an expression follows.

  The s stands for substitute, while the g stands for global, which means that all matching occurrences in the line would be replaced

  </aside>

ifconfig en1 | grep broadcast

• en1 = Wi-Fi interface

netstat -nr | grep default | grep en0

• netstat = Displays network-related information such as open connections, open socket ports, etc.
• -n = Show statistics recorded by the memory management routines
• -r = Show the routing tables

host who.int

• host = DNS lookup utility
  • Used to convert names to IP addresses

/etc/resolv.conf

nslookup who.int 8.8.8.8

• Query internet name servers interactively
• Query name server(s) for various domain records

First dig + short who.int

• Find IP address
• dig = Lookup the IP associated with a hostname (A records)

then whois <that ip>

• whois = Internet domain name and network number directory service
  • Get information about a domain name

dig +short 42.fr

• Pretty much same thing as 05

traceroute who.int

• Print the route packets take to network host

nat (10.60.1.1) = NAT Server

• NAT = Network address translation
  • Translating a private IP to public Ip that can be read on the internet

ipconfig getoption en0 server_identifier

• ipconfig = View and control IP configuration stage
• getoption: interface-name (option-name)
  • Prints the DHCP option with the given name

host $(ipconfig getifaddr en0)

• getifaddr en0 = Prints IP address
• host <that ip> = Reverse lookup an IP

/etc/hosts

write “46.19.122.85 intra.42.fr” to /etc/hosts