fix 110.fw example

[pve-firewall.git] / README

Experimental software, only used for testing!
=============================================


Quick Intro
===========

VM firewall rules are read from /etc/pve/firewall/<VMID>.fw

Security group rules are read from /etc/pve/firewall/groups.fw

Host firewall rules are read from /etc/pve/local/host.fw

You can find examples in the example/ dir


Use the following command to mange the firewall:

To test the firewall configuration:

./pvefw compile

To start or update the firewall:

./pvefw start

To update the firewall rules (the firewall is not started if it
is not already running):

./pvefw update

To stop the firewall:

./pvefw stop


Implementation details
======================

We write iptables rules directly, an generate the following chains 
as entry points in the 'forward' table:

PVEFW-INPUT
PVEFW-OUTPUT
PVEFW-FORWARD

We do not touch other (user defined) chains.

Each VM can have its own firewall definition file in 

/etc/pve/firewall/<VMID>.fw

That file has a section [RULES] to define firewall rules.

Format is: TYPE ACTION IFACE SOURCE DEST PROTO D-PORT S-PORT

* TYPE: IN|OUT|GROUP 
* ACTION: action or macro
* IFACE: vm network interface (net0 - net5), or '-' for all interfaces
* SOURCE: source IP address, or '-' for any source
* DEST: dest IP address, or '-' for any destination address
* PROTO: see /etc/protocols
* D-PORT: destination port
* S-PORT: source port

A rule for inbound traffic looks like this:

IN SSH(ACCEPT) net0

Outbound rules looks like:

OUT SSH(ACCEPT)

Problems
===================

There are a number of restrictions when using iptables to filter
bridged traffic. The physdev match feature does not work correctly
when traffic is routed from host to bridge:

  * when a packet being sent through a bridge entered the firewall on another interface 
    and was being forwarded to the bridge.

  * when a packet originating on the firewall itself is being sent through a bridge.

So we disable the firewall if we detect such case (bridge with assigned IP address).
You can enable it again (if you do not care) by setting "allow_bridge_route: 1" in "host.fw".

The correct workaround is to remove the IP address from the bridge device, and
use a veth device which is plugged into the bridge:

---/etc/network/interfaces----

...

auto vmbr0
iface vmbr0 inet manual
	bridge_ports bond0
	bridge_stp off
	bridge_fd 0

# this create the veth device and plug it into vmbr0
auto pm0
iface pm0 inet static
	address  192.168.10.10
	netmask  255.255.255.0
	gateway  192.168.10.1
	VETH_BRIDGETO vmbr0

auto vmbr1
iface vmbr1 inet manual
      bridge_ports none
      bridge_stp off
      bridge_fd 0

# setup masqueraded bridge port vmbr1/pm1 using pm0
# NOTE: this needs kernel 3.10.0 or newer (for conntrack --zone) 
auto pm1
iface pm1 inet static
       address 10.10.10.1
       netmask 255.255.255.0
       VETH_BRIDGETO vmbr1
       VETH_MASQUERADE pm0

...

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