One Click Virtualization

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FAQ ​

KVM not available / /dev/kvm does not exist ​

Check if the host supports hardware virtualization:

bash
egrep -c '(vmx|svm)' /proc/cpuinfo
ls /dev/kvm

If you cannot use KVM on a VPS, the host may not support nested virtualization. Please contact your VPS provider to confirm.

virsh: command not found ​

The QEMU/KVM environment was not installed correctly. Please re-run the installation script:

shell
bash <(curl -sSL https://raw.githubusercontent.com/oneclickvirt/qemu/main/qemuinstall.sh)

VM cannot access the internet (IPv4) ​

Check if the iptables NAT rules exist:

shell
iptables -t nat -L POSTROUTING -n -v | grep virbr

If not, add them manually (assuming virbr0 subnet is 192.168.122.0/24):

shell
iptables -t nat -A POSTROUTING -s 192.168.122.0/24 ! -d 192.168.122.0/24 -j MASQUERADE
iptables -A FORWARD -s 192.168.122.0/24 -j ACCEPT
iptables -A FORWARD -d 192.168.122.0/24 -j ACCEPT

VM IPv6 not working ​

  1. Confirm the host has a public IPv6 address
  2. Check if the IPv6 bridge is configured:
shell
ip -6 addr show
  1. Confirm the installation script fully executed and configured the IPv6 network.

VM fails to start / status is shut off ​

Check the VM error log:

shell
virsh dominfo vm1
cat /var/log/libvirt/qemu/vm1.log

Common causes:

  • Insufficient memory: check available memory with free -h
  • Insufficient disk space: check disk with df -h
  • KVM permission issue: confirm /dev/kvm permissions are correct

How to view SSH login info ​

View the vmlog file for batch-created VM info:

shell
cat vmlog

Or view port forwarding rules:

shell
iptables -t nat -L PREROUTING -n -v | grep 25000

How to completely reset the QEMU/KVM environment ​

Uninstall first, then reinstall:

shell
bash <(curl -sSL https://raw.githubusercontent.com/oneclickvirt/qemu/main/scripts/qemuuninstall.sh)
bash <(curl -sSL https://raw.githubusercontent.com/oneclickvirt/qemu/main/qemuinstall.sh)

No-CDN mode (WITHOUTCDN) ​

If your network is stable and useful, or you want to fully disable CDN acceleration, set this before running scripts:

shell
export WITHOUTCDN=TRUE

You can also apply it to a single command only:

shell
WITHOUTCDN=TRUE

When enabled, scripts will no longer try CDN acceleration URLs during execution.