IPV4 Nat configuration ?

[Bastian Scott]

Good Morning Proxmox Forum,

I'm totally new to networking under Linux and i need some help with it

i actually have 3 Public ip's and i would to like to put these on 3 VM's ( later on more VMs )
so, the Server in the same network can ping each other, the gateway is reachable, but .... i can't ping to the World ... but eth0:3 works (pinging from my home pc to the public ip)... serieusly i dont know that to do anymore


OS: Debian 8.3
Proxmox 4

here my /etc/network/interfaces config:


auto eth0
iface eth0 inet static
address XXX.XXX.XXX.145
netmask 255.255.255.224
gateway XXX.XXX.XXX.129
broadcast XXX.XXX.XXX.159
post-up echo 1 > /proc/sys/net/ipv4/conf/eth0/proxy_arp

#neue ip Adressen
auto eth0:1
iface eth0:1 inet static
address XXX.XXX.XXX.98
netmask 255.255.255.248
network XXX.XXX.XXX.97
broadcast XXX.XXX.XXX.103
hwaddress ether XX:XX:XX:XX:XX:XX

auto eth0:2
iface eth0:2 inet static
address XXX.XXX.XXX.99
netmask 255.255.255.248
network XXX.XXX.XXX.97
broadcast XXX.XXX.XXX.103
hwaddress ether XX:XX:XX:XX:XX:XX

auto eth0:3
iface eth0:3 inet static
address XXX.XXX.XXX.101
netmask 255.255.255.248
network XXX.XXX.XXX.97
broadcast XXX.XXX.XXX.103
hwaddress ether XX:XX:XX:XX:XX:XX

auto vmbr0
iface vmbr0 inet static
address XXX.XXX.117.1
netmask 255.255.255.0
bridge_ports none
bridge_stp off
bridge_fd 0
post-up echo 1 > /proc/sys/net/ipv4/ip_forward
#natting interface vmbr0
post-up iptables -t nat -A POSTROUTING -p tcp -s 'XXX.XXX.XXX.98/29' -o vmbr0 -j MASQUERADE
post-up iptables -t nat -A POSTROUTING -p udp -s 'XXX.XXX.XXX.98/29' -o vmbr0 -j MASQUERADE
post-down iptables -t nat -D POSTROUTING -p tcp -s 'XXX.XXX.XXX.98/29' -o vmbr0 -j MASQUERADE
post-down iptables -t nat -D POSTROUTING -p udp -s 'XXX.XXX.XXX.98/29' -o vmbr0 -j MASQUERADE


auto vmbr1
iface vmbr1 inet static
address XXX.XXX.118.1
netmask 255.255.255.0
bridge_ports none
bridge_stp off
bridge_fd 0
post-up echo 1 > /proc/sys/net/ipv4/ip_forward

auto vmbr2
iface vmbr2 inet static
address XXX.XXX.119.1
netmask 255.255.255.0
bridge_ports none
bridge_stp off
bridge_fd 0
post-up echo 1 > /proc/sys/net/ipv4/ip_forward

 

[wbumiller]

I noticed two things: /proc/sys/net/ipv4/ip_forward is just the general forwarding switch, you'll also want to enable /proc/sys/net/ipv4/conf/vmbr0/forwarding (and for vmbr1 and 2, too).
And about 'ping'... you're only masquerading tcp and udp while ping uses icmp ;-)