Network & IPs

Quick guide to Additional IPv4, IPv6, Reverse DNS (PTR), and routed subnets. This page focuses on the most common questions and practical steps.

Frequently Asked Topics

How to get and use an additional IPv4
How to enable and configure IPv6 on the VPS
How to set Reverse DNS (PTR) for my IP
How routed subnets work (e.g., /29) and how to configure them
How to verify network and diagnose issues

Additional IPv4

Additional IPv4 addresses can be assigned to your VPS. Once assigned in the panel, configure them inside the guest OS.

Linux (Debian/Ubuntu) example

# Check current primary interface name first
ip -br addr

# Example: add an additional IPv4 (replace values)
PRIMARY_IF=eth0
NEW_IP=203.0.113.10
PREFIX=24          # use the netmask/prefix we provide
GATEWAY=203.0.113.1 # your network gateway

# Add address immediately (temporary, until reboot)
sudo ip addr add ${NEW_IP}/${PREFIX} dev ${PRIMARY_IF}

# Ensure routing (usually your default route already points to $GATEWAY)
sudo ip route add ${NEW_IP}/32 dev ${PRIMARY_IF} || true

# Persist configuration (Netplan example on Ubuntu)
# /etc/netplan/01-netcfg.yaml
network:
  version: 2
  ethernets:
    ${PRIMARY_IF}:
      addresses:
        - 203.0.113.5/24      # your primary IP/prefix
        - 203.0.113.10/24     # additional IP
      gateway4: 203.0.113.1
      nameservers:
        addresses: [1.1.1.1, 8.8.8.8]

# Apply
sudo netplan apply

Windows example (PowerShell)

# List adapters
Get-NetAdapter | Format-Table -Auto Name, Status, MacAddress

# Add IPv4 to an interface
$if = Get-NetAdapter -Name "Ethernet"
New-NetIPAddress -InterfaceIndex $if.ifIndex -IPAddress 203.0.113.10 -PrefixLength 24 -DefaultGateway 203.0.113.1

# Add DNS servers
Set-DnsClientServerAddress -InterfaceIndex $if.ifIndex -ServerAddresses 1.1.1.1,8.8.8.8

Note: Do not create multiple default gateways. Keep a single default route via the primary IP’s gateway.

IPv6

If IPv6 is available for your VPS, you’ll receive a single IPv6 address or a routed range. Enable IPv6 in your OS and add the address.

Linux example (Netplan)

# /etc/netplan/01-netcfg.yaml
network:
  version: 2
  ethernets:
    eth0:
      addresses:
        - 2001:db8:1234:567::10/64   # your assigned IPv6
      gateway6: 2001:db8:1234:567::1 # your IPv6 gateway
      nameservers:
        addresses: [2606:4700:4700::1111, 2001:4860:4860::8888]

Apply with:

sudo netplan apply

Add IPv6 temporarily

sudo ip -6 addr add 2001:db8:1234:567::10/64 dev eth0
sudo ip -6 route add default via 2001:db8:1234:567::1 dev eth0

Windows example (PowerShell)

$if = Get-NetAdapter -Name "Ethernet"
New-NetIPAddress -InterfaceIndex $if.ifIndex -IPAddress 2001:db8:1234:567::10 -PrefixLength 64 -DefaultGateway 2001:db8:1234:567::1
Set-DnsClientServerAddress -InterfaceIndex $if.ifIndex -ServerAddresses 2606:4700:4700::1111,2001:4860:4860::8888

Tip: Some applications need to be explicitly bound to IPv6 or configured to prefer IPv6.

Reverse DNS (PTR)

Reverse DNS maps an IP address to a hostname (PTR record). This is often required for email deliverability and some security checks.

How to set PTR

Open the control panel and locate your IP address
Find the "Reverse DNS" or "PTR" setting for that IP
Enter a fully qualified domain name (FQDN), e.g., server-1.example.com
Save the change

Notes

The FQDN must resolve forward (A/AAAA) to the same IP for best results
Propagation can take several minutes to a few hours
Use only FQDNs you control; set up matching A/AAAA records in your DNS

Verify PTR

# Check PTR
host 203.0.113.10

# Or with dig
dig -x 203.0.113.10 +short

# Forward check
dig server-1.example.com A +short

A routed subnet means the additional IP block is routed to your VPS via its primary interface. You do not bridge or add a second gateway; you assign IPs to interfaces (or to guests/containers) and route through the main server.

Example: Use a /29 on Linux

Assume:

Main VPS IP (primary): 203.0.113.5/24, gateway 203.0.113.1
Routed subnet: 198.51.100.0/29 (usable: 198.51.100.1–198.51.100.6)

Two common patterns:

Assign one IP to the VPS itself

# Add one address from the /29 to eth0
sudo ip addr add 198.51.100.2/32 dev eth0

# Ensure traffic for the /29 is accepted locally
sudo ip route add 198.51.100.0/29 dev eth0 || true

Route the /29 to downstream guests (KVM/LXC/Docker)

# On the VPS host: route the whole /29 through the primary interface
sudo ip route add 198.51.100.0/29 dev eth0

# Assign individual /32 addresses to guest vNICs or veth
# and SNAT/forward as needed; enable IP forwarding:
echo 1 | sudo tee /proc/sys/net/ipv4/ip_forward
sudo sysctl -w net.ipv4.ip_forward=1

# Optional: basic forwarding/NAT example (adapt as needed)
sudo iptables -t nat -A POSTROUTING -s 198.51.100.0/29 -o eth0 -j MASQUERADE
sudo iptables -A FORWARD -s 198.51.100.0/29 -j ACCEPT
sudo iptables -A FORWARD -d 198.51.100.0/29 -j ACCEPT

Important: Do not add a second default gateway for the routed block. Keep the original default route via the primary IP’s gateway.

Troubleshooting & Verification

Show addresses: ip -br addr
Routes: ip route, IPv6: ip -6 route
Connectivity: ping, ping6 or ping -6, traceroute, mtr
DNS: dig, nslookup
Windows: Get-NetIPAddress, Test-NetConnection, Resolve-DnsName

Common issues

Added IP works until reboot: persist config (Netplan/systemd-networkd/NetworkManager)
Multiple default gateways cause loss of connectivity: keep only one default route
Firewall blocks traffic: check UFW/firewalld/Windows Defender Firewall
Wrong prefix/gateway: confirm values from the panel before applying

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