How to create a bridge for KVM without binding to eth*, but with Internet access?

Question

Computer networks

I have a small task. I need to create a bridge br1 with Internet access and without being tied to a physical interface. What I did:
My interface is br1

DEVICE=br1
TYPE=Bridge
ONBOOT=yes
BOOTPROTO=static
IPADDR=192.168.1.1
NETMASK=255.255.255.0
NM_CONTROLLED=no

In iptables I wrote this:

iptables -t nat -A POSTROUTING -s 192.168.1.0/24 -j SNAT --to-source 192.168.122.1

192.168.122.1, my IP address, which has Internet access
Do you think that this is enough, since virbr0 has Internet access, but when I bind br1 to my virtual machine, there is no Internet. Maybe I forgot some other rules? Tell me please

Answer 1

sysctl -w net.ipv4.ip_forward=1
well, if forward is disabled for everyone in the firewall, then enable