[Notes] Network Planning and Administration: Physical Transmission Media

Miguel Menéndez

Physical means of data transmission.

VMware Workstation

  • Virtual machines in .ova file are imported (simply opening them in File -> Open…). To open a virtual machine without importing it: Open .vmx file.
  • For NAT, the virtual switch is VMnet8 (only one NAT, there cannot be two). The host IP is 192.168.241.1 and the gateway is 192.168.241.2.
  • In bridged, the virtual switch is VMnet0, the IPs assigned to the virtual machines are from the network of the host machine.
  • In host-only, the virtual switch is VMnet1, there is no gateway so there will be no access to the internet although the machines will see each other (network 192.168.58.0) .
  • Custom by default will be VMnet* and type host-only. But by disabling DHCP and disconnecting it from the host (in the adapter properties in VMware) it becomes LAN Segment.
  • LAN Segment does not have DHCP and does not include the host.

Commands

  • arp -a (on win and gnu/linux to see ip, mac, network adapter open connections)
  • ipconfig /all (win only, to see all network adapters)
  • ifconfig -a (gnu/linux only, to see all network adapters)
  • route -n (in gnu/linux to see gateway)
  • tracert (win) traceroute (gnu/linux)

In general, on GNU/Linux distributions, arp, ifconfig, and route are in the net-tools package. Traceroute usually has its own traceroute package.

Subnet Calculator

vlsm-calc.net

subnettingpractice.com/vlsm.html

Configure network in GNU/Linux

# nano /etc/network/interfaces

Where says

auto ens33
iface ens33 inet dhcp

Should say

auto ens33
iface ens33 inet static
    address 172.16.0.99
    netmask 255.255.255.0
    gateway 172.16.0.254
    dns-nameservers 1.1.1.1 8.8.8.8
# shutdown -r now

⚠️ For Ubuntu 18, see how to configure netplan .

Configure GNU/Linux as a router (forwarder)

Requires two network adapters. In this example, ens33 (bridged in VMware) will be the external network adapter, ens37 (LAN Segment in VMware) the internal network adapter (ifconfig -a to see all network adapters):

# nano /etc/network/interfaces

Where says

auto ens33
iface ens33 inet static
    address 172.16.0.99
    netmask 255.255.255.0
    gateway 172.16.0.254
    dns-nameservers 1.1.1.1 8.8.8.8

Should say

auto ens33
iface ens33 inet static
    address 172.16.0.99
    netmask 255.255.255.0
    gateway 172.16.0.254
    dns-nameservers 1.1.1.1 8.8.8.8

auto ens37
iface ens37 inet static
    address 172.16.99.254
    netmask 255.255.255.0

⚠️ For Ubuntu 18, see how to configure netplan .

# shutdown -r now
# nano /etc/sysctl.conf

Where says

#net.ipv4.ip_forward=1

Should say

net.ipv4.ip_forward=1

# Disable IPv6:
#net.ipv6.conf.all.disable_ipv6=1
# sysctl -p

Comments

Found a bug? Do you think something could be improved? Feel free to let me know and I will be happy to take a look.