Network Managers

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Ubuntu - Netplan
Before making changes to the network configuration on an Ubuntu machine, ensure that Cloud-init isn't enabled. Cloud-init is essentially Canonicals attempt at having Ubuntu servers fully configure themselves, in terms of networking, Cloud-init will force an Ubuntu machine to attempt to automatically configure it's networking
 
Netplan uses .yaml files for network configuration, these are stored in /etc/netplan
Check DHCP IP leases info
netplan ip leases interfacename
Changes to interfaces are made in the .yaml files, once changes have been made they need to be applied.
To test changes, use the try command. This essentially implements the change for a set amount of time, after which the change is reverted.
netplan try
You can also set a custom timeout time using the below command:
netplan try --timeout=15
To permanently apply a change, use the below command:
netplan apply
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RHEL - nmcli
Network configuration files are stored in /etc/syconfig/network-scripts. Files stored within this directory shouldn't really be edited - these are used for functionality of the ifconfig command, rather than being the interface configuration itself.
Viewing network configuration
View interface connections
nmcli connection show
View interface device status
nmcli device status
View network device configuration
nmcli device show devicename
Editing network settings & configuration
Edit connection settings
nmcli connection edit connectionname
From here, you can edit any of the settings shown in the 'nmcli device show devicename' command
As an example, the below could be used to change the default gateway IP
set ipv4.gateway 10.0.0.2
You would then want to save changes, you're given the option to trial the change or save it permanently
save persistent
or
save temporary
The above uses the nmcli cli to make changes, you can also format commands as below to make changes without entering the dedicated cli:
Add an additional IP to a connection
nmcli connection modify connectionname ipv4.addresses oldIP, newIP
Delete a connection
nmcli connection delete connectionname
Once changes have been made via nmcli, the interface will need restarting
nmcli connection down
nmcli connection up
or
nmcli connection reload
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OpenSUSE - Wicked
Network configuration files are stored in /etc/sysconfig/networks
systemctl status network
Show all interfaces
wicked show all
Show info for specific interface
wicked show eth1
Take interface down or up
wicked ifdown eth1
wicked ifup eth1