Tag: Network

How to add secondary IP address using nmcli

On an AlmaLinux 9 server, I wanted to add secondary IPs to a server. First, I checked the network interface device name used in the server with the command

ip a

The current public IP address was assigned to the network interface with the name enp13s0. To see how it is configured, I run

cd /etc
grep -irl enp13s0

That showed the server am using Network Manager to configure the IP address

[root@node4 etc]# grep -irl enp13s0
NetworkManager/system-connections/enp13s0.nmconnection
[root@node4 etc]#

You can add additional IP adding using nmcli command.

nmcli con mod DEVICE_NAME +ipv4.addresses "IP_ADDR/24"

Example

nmcli con mod enp13s0 +ipv4.addresses "67.222.158.35/24"
nmcli con mod enp13s0 +ipv4.addresses "67.222.158.36/24"
nmcli con mod enp13s0 +ipv4.addresses "67.222.158.37/24"
nmcli con mod enp13s0 +ipv4.addresses "67.222.158.38/24"
nmcli con mod enp13s0 +ipv4.addresses "67.222.158.39/24"
nmcli con mod enp13s0 +ipv4.addresses "67.222.158.40/24"
nmcli con mod enp13s0 +ipv4.addresses "67.222.158.41/24"

To make the IPs online, run

nmcli con up enp13s0

Now ip a command lists all secondary IP addresses

[root@node4 etc]# ip a show enp13s0
2: enp13s0:  mtu 1500 qdisc fq_codel state UP group default qlen 1000
    link/ether 74:56:3c:31:38:0a brd ff:ff:ff:ff:ff:ff
    inet 67.222.158.34/24 brd 67.222.158.255 scope global noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.35/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.36/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.37/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.38/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.39/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.40/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet 67.222.158.41/24 brd 67.222.158.255 scope global secondary noprefixroute enp13s0
       valid_lft forever preferred_lft forever
    inet6 fe80::7656:3cff:fe31:380a/64 scope link noprefixroute 
       valid_lft forever preferred_lft forever
[root@node4 etc]#

To list all network interface devices using nmcli, run

[root@node4 etc]# nmcli connection show
NAME          UUID                                  TYPE      DEVICE       
enp13s0       4ca2de2f-1f4d-38e2-84fc-4d17aafc2514  ethernet  enp13s0      
docker0       521f050e-7870-43b3-a6ca-618d45116b03  bridge    docker0      
[root@node4 etc]#

Back to IP

February 7, 2023

systemd-networkd

systemd-networkd configuration files are stored in /etc/systemd/network/

Example

/etc/systemd/network/05-eth0.network

Here is a sample config

[Match]
Name=eth0

[Network]
DHCP=no
DNS=172.105.170.5 172.105.161.5 172.105.171.5
Domains=members.linode.com
IPv6PrivacyExtensions=false

Gateway=194.195.127.1
Address=194.195.127.150/24

To restart systemd-networkd

systemctl restart systemd-networkd

See IP

November 14, 2022

nmcli
- How to add secondary IP address using nmcli
February 7, 2022
Configure Failover IP in Ubuntu 20.04 OVH VPS
To configure IP on OVH VPS, you need to manually configure networking as OVH gateway is outside the failover IP subnet. For most hosting providers getaway will be in the same subnet as the IP address. To configure IP using netplan, see instruction here.

First, install ifupdown package
```
apt install -y ifupdown
```
Now edit file
```
vi /etc/network/interfaces
```
Add
```
auto NETWORK_INTERFACE_HERE
iface NETWORK_INTERFACE_HERE inet static
    address FO_IP_ADDR
    netmask 255.255.255.255
    broadcast FO_IP_ADDR
    dns-nameservers 8.8.8.8 8.8.4.4
    post-up ip route add GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
    post-up ip route add default via GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
    pre-down ip route del GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
    pre-down ip route del default via GATEWAY_ADDR dev NETWORK_INTERFACE_HERE
```
In the above text, replace

NETWORK_INTERFACE_HERE = with your actual network interface name, for example, eth0, ens18, etc.
FO_IP_ADDR = Your VPS IP address, OVH calls this Failover IP address. It is just any secondary IP address you purchase.
GATEWAY_ADDR = Gateway IP address. This is the same as the Main IP of the server with the last octal replaced by 254

Example

Configuration is the same as Ubuntu 18.04, the only difference is post-up and pre-down tines, where Ubuntu 18.04 used older route command, in Ubuntu 20.04, we use “ip route” command instead.
November 26, 2021
Change Unidentified Network from public in windows 7
After upgrading Main computer (one that connect to DSL modem) on LAN, other PC’s are able to get internet. But failed to ping on 192.168.0.1.

Method 1

Go to
```
Start > Search > secpol.msc
```
Navigate to
```
Network List Manager Policies > Unidentified Networks
```
Double Click and Change Location Type to
```
Private
```
Warning This means from now on all Unidentified Networks will be set as private!!

Method 2

NOTE: This is temporary solution, on rebooting, changes will be lost

This is caused by Network card that connect to lan with IP 192.168.0.1 is assigned as a “Public Network”. Public Network have many features disabled for security.

To fix this, run “ChangeCategory.psl” on Power Shell running as Administrator.

Copy and paste following content to a text file, save it as ChangeCategory.psl
```
$NLMType = [Type]::GetTypeFromCLSID('DCB00C01-570F-4A9B-8D69-199FDBA5723B')
$INetworkListManager = [Activator]::CreateInstance($NLMType)

$NLM_ENUM_NETWORK_CONNECTED  = 1
$NLM_NETWORK_CATEGORY_PUBLIC = 0x00
$NLM_NETWORK_CATEGORY_PRIVATE = 0x01
$UNIDENTIFIED = "Unidentified network"

$INetworks = $INetworkListManager.GetNetworks($NLM_ENUM_NETWORK_CONNECTED)

foreach ($INetwork in $INetworks)
{
    $Name = $INetwork.GetName()
    $Category = $INetwork.GetCategory()

    if ($INetwork.IsConnected -and ($Category -eq $NLM_NETWORK_CATEGORY_PUBLIC) -and ($Name -eq $UNIDENTIFIED))
    {
        $INetwork.SetCategory($NLM_NETWORK_CATEGORY_PRIVATE)
    }
}
```
Now run power shell as administrator.

Type
```
set-executionpolicy remotesigned
ChangeCategory.ps1 
```
This should be done in folder where ChangeCategory.ps1 is saved.

After doing this, Network and Sharing Center will show

Windows Firewall will show “undefined network” in “Home or work (private) networks”. Being in private network, you get privileges to share, ping etc…

See Windows
February 20, 2011

Tag: Network

How to add secondary IP address using nmcli

systemd-networkd

nmcli

Configure Failover IP in Ubuntu 20.04 OVH VPS

Change Unidentified Network from public in windows 7

Method 1

Method 2