Linux Networking - keshavbaweja-git/guides GitHub Wiki

  • Hostnames are configured in /etc/hosts

  • DNS Server is configured in /etc/resolv.conf

nameserver 192.168.1.100
nameserver 8.8.8.8 # Internet name server hosted by Google
search mycompany.com # Appended to hostnames specified without FQDN
  • /etc/hosts takes precedence over DNS server, however this precedence can be configured to look at DNS server first.
  • DNS Server can be configured to forward all unknown hostnames to another DNS server like 8.8.8.8
  • DNS Record Types
    • A (domain_name -> IPv4)
    • AAAA (domain_name -> IPv6)
    • CNAME (domain_name -> domainName2)
  • nslookup <domain_name>, nslookup ignores entries in /etc/hosts 
# Create an ip link with virtual eth interfaces
ip link add <veth-1> type veth peer name <veth-2>
ip link add veth-red type veth peer name veth-blue

# Attach a virtual eth interface to a network namespace
ip link set <veth> netns <network-ns>
ip link set veth-red netns red
ip link set veth-blue netns blue

# Delete an ip-link
ip -n red link del veth-red # veth interface on both sides of the link are deleted



# Assign IP Address to virtual eth interface
ip -n red addr add 192.168.15.1 dev veth-red
ip -n blue add add 192.168.15.2 dev veth-blue

# Bring up virtual eth interfaces
ip -n red link set veth-red up
ip -n blue link set veth-blue up

# Create a virtual switch for namespaces using Linux Bridge
# It is visible as another network interface on the host machine
ip link add <switch-name> type bridge
ip link add v-net-0 type bridge

# Activate virtual switch
ip link set dev v-net-0 up

# Create a link for a network namespace and virtual switch
ip link add veth-red type veth peer name veth-red-br
ip link set veth-red netns red
ip link set veth-red-br master veth-net-0
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