Create NAT Bridge in Proxmox

Tested on Proxmox on Debian 8.

Modify /etc/network/interfaces to add NAT iptables

auto vmbr1
iface vmbr1 inet static
        address  100.64.43.1
        netmask  255.255.255.0
        bridge_ports none
        bridge_stp off
        bridge_fd 0
        post-up echo 1 > /proc/sys/net/ipv4/ip_forward
        post-up   iptables -t nat -A POSTROUTING -s '100.64.43.0/24' -o eth0 -j MASQUERADE
        post-down iptables -t nat -D POSTROUTING -s '100.64.43.0/24' -o eth0 -j MASQUERADE

Install dnsmasq
```
apt install -y dnsmasq
```

Modify /etc/dnsmasq.d/config

/etc/dnsmasq.d/config

domain-needed
bogus-priv
local=/cloud/
domain=cloud
dhcp-fqdn
interface=vmbr1
bind-interfaces
dhcp-range=100.64.43.200,100.64.43.250,72h
dhcp-option=option:router,100.64.43.1
dhcp-option=option:dns-server,100.64.43.1

If IPv6 is available, append this snippets

/etc/dnsmasq.d/config

enable-ra
dhcp-range=2001:xxxx:xxxx:xxxx::1000,2001:xxxx:xxxx:xxxx::1fff
dhcp-option=option6:dns-server,[2001:xxxx:xxxx:xxxx::]

Enable and start dnsmasq

systemctl enable dnsmasq
systemctl restart dnsmasq

proxmox, nat, dnsmasq