I have recently switched my network configuration from 2 routed subnets;

192.168.0.0/24
192.168.5.0/24

To a single subnet;

192.168.0.0/21

I had hoped this would have little to no impact and be a seamless transition (how wrong I was). I have a mix of devices with both dynamic (DHCP) and static IP addresses. Those using DHCP didn’t cause much of an issues, but those configured using static addresses required the subnet mask and default gateway changing (again, fairly straight forward).

The real issue came when it came to changing my vCenter Server Appliance (VCSA) network configuration. The obvious place to look (and several articles online) pointed toward the configuration option inside the vSphere Web Client; System Configuration -> Nodes -> x ->Manage -> Settings -> Common -> Networking

vc_network_settings

Unfortunately the settings are grayed out with a message “IPv4 configuration for nic0 of this node cannot be edited post deployment.”.

Other articles pointed toward the console (alt-f2 option), vmware Appliance Management Interface (VAMI) running on https://your-vc-hostname-or-ip:5480/ or SSH; Unfortunately I couldn’t login to try any of these techniques.

Console -> Alt-F2- “Authentication failed; Invalid login or password.”
SSH- “Login incorrect”
VAMI- “Unable to authenticate user. Please try again”

This had me stumped for many hours. I was able to reset the root password (reset the VM, prevent vcsa autoboot by pressing any key when the grub bootloader appears, press p, enter the grub password (default is vmware), enter, press e, add init=/bin/bash, enter, press b then type passwd root) but still couldn’t login using the new password. I think a few issues were at play here, but eventually tracked it down to the password complexity requirement forcing the use of special characters which were in turn being transposed by RDP / vSphere (” was becoming @ and £ was becoming # etc). Once I had figured the password issue I was then able to try the techniques again;

Console -> Alt-F2 -> Configure Management Network -> IP Configurationvc_consoleNope- “Configure Management Network; Management network configuration not allowed”

Next… SSH -> /opt/vmware/share/vami/vami_config_netvc_libxml2modNope- Lots of errors stating “ImportError: No module named libxml2mod”

Finally… VAMIvmaiAgain, no joy- “Updating has been disabled”.

Eventually I decided to try the same technique i’d previously used to modify my Linux (CentOS) VMs.

I started an SSH session and modified /etc/sysconfig/network/routes (from default 192.168.0.1 to 192.168.5.1 and then /etc/sysconfig/network/ifcfg-eth0 (NETMASK=’255.255.255.0′ becomes NETMASK=’255.255.248.0′). Rebooted and voila!

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