FAQ

KVM not available / /dev/kvm does not exist

Check if the host supports hardware virtualization:

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:

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:

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

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

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:

ip -6 addr show

3. Confirm the installation script fully executed and configured the IPv6 network.

VM fails to start / status is shut off

Check the VM error log:

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:

cat vmlog

Or view port forwarding rules:

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

How to completely reset the QEMU/KVM environment

Uninstall first, then reinstall:

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)