firewall: add a 'Notes on IPv6' section

[pve-docs.git] / pve-firewall.adoc

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NAME
----

pve-firewall - The PVE Firewall Daemon


SYNOPSYS
--------

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DESCRIPTION
-----------
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{pve} Firewall
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// Copied from pve wiki: Revision as of 08:45, 9 November 2015

Proxmox VE Firewall provides an easy way to protect your IT
infrastructure. You can easily setup firewall rules for all hosts
inside a cluster, or define rules for virtual machines and
containers. Features like firewall macros, security groups, IP sets
and aliases help making that task easier.

While all configuration is stored on the cluster file system, the
iptables based firewall runs on each cluster node, and thus provides
full isolation between virtual machines. The distributed nature of
this system also provides much higher bandwidth than a central
firewall solution.

NOTE: If you enable the firewall, all traffic is blocked by default,
except WebGUI(8006) and ssh(22) from your local network.


Zones
-----

The Proxmox VE firewall groups the network into the following logical zones:

Host::

Traffic from/to a cluster node

VM::

Traffic from/to a specific VM

For each zone, you can define firewall rules for incoming and/or
outgoing traffic.


Ports used by Proxmox VE
------------------------

* Web interface: 8006
* VNC Web console: 5900-5999
* SPICE proxy: 3128
* sshd (used for cluster actions): 22
* rpcbind: 111
*  corosync multicast (if you run a cluster): 5404, 5405 UDP


Configuration
-------------

All firewall related configuration is stored on the proxmox cluster
file system. So those files are automatically distributed to all
cluster nodes, and the 'pve-firewall' service updates the underlying
iptables rules automatically on any change. Any configuration can be
done using the GUI (i.e. Datacenter -> Firewall -> Options tab (tabs
at the bottom of the page), or on a Node -> Firewall), so the
following configuration file snippets are just for completeness.

Cluster wide configuration is stored at:
 
 /etc/pve/firewall/cluster.fw

The firewall is completely disabled by default, so you need to set the
enable option here:

----
[OPTIONS]
# enable firewall (cluster wide setting, default is disabled)
enable: 1
----

The cluster wide configuration can contain the following data:

* IP set definitions
* Alias definitions
* Security group definitions
* Cluster wide firewall rules for all nodes

VM firewall configuration is read from:

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

and contains the following data:

* IP set definitions
* Alias definitions
* Firewall rules for this VM
* VM specific options

And finally, any host related configuration is read from:

 /etc/pve/nodes/<nodename>/host.fw

This is useful if you want to overwrite rules from 'cluster.fw'
config. You can also increase log verbosity, and set netfilter related
options.

Enabling the Firewall for VMs and Containers
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

You need to enable the firewall on the virtual network interface configuration
in addition to the general 'Enable Firewall' option in the 'Options' tab.

Firewall Rules
~~~~~~~~~~~~~~

Any firewall rule consists of a direction (`IN` or `OUT`) and an
action (`ACCEPT`, `DENY`, `REJECT`). Additional options can be used to
refine rule matches. Here are some examples:

----
[RULES]

#TYPE ACTION [OPTIONS]
#TYPE MACRO(ACTION) [OPTIONS]

# -i      <INTERFACE>
# -source <SOURCE>
# -dest   <DEST>
# -p      <PROTOCOL>
# -dport  <DESTINATION_PORT>
# -sport  <SOURCE_PORT>

IN SSH(ACCEPT) -i net0
IN SSH(ACCEPT) -i net0 # a comment
IN SSH(ACCEPT) -i net0 -source 192.168.2.192  # only allow SSH from 192.168.2.192
IN SSH(ACCEPT) -i net0 -source 10.0.0.1-10.0.0.10 # accept SSH for ip range
IN SSH(ACCEPT) -i net0 -source 10.0.0.1,10.0.0.2,10.0.0.3 #accept ssh for ip list
IN SSH(ACCEPT) -i net0 -source +mynetgroup   # accept ssh for ipset mynetgroup
IN SSH(ACCEPT) -i net0 -source myserveralias   #accept ssh for alias myserveralias

|IN SSH(ACCEPT) -i net0 # disabled rule
----

Security Groups
~~~~~~~~~~~~~~~

A security group is a collection of rules, defined at cluster level, which
can be used in all VMs' rules. For example you can define a group named
`webserver` with rules to open the http and https ports.

----
# /etc/pve/firewall/cluster.fw

[group webserver]
IN  ACCEPT -p tcp -dport 80
IN  ACCEPT -p tcp -dport 443
----

Then, you can add this group to a VM's firewall

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

[RULES]
GROUP webserver
----


IP Aliases
~~~~~~~~~~

IP Aliases allow you to associate IP addresses of networks with a
name. You can then refer to those names:

* inside IP set definitions
* in `source` and `dest` properties of firewall rules

Standard IP alias `local_network`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This alias is automatically defined. Please use the following command
to see assigned values:

----
# pve-firewall localnet
local hostname: example
local IP address: 192.168.2.100
network auto detect: 192.168.0.0/20
using detected local_network: 192.168.0.0/20
----

The firewall automatically sets up rules to allow everything needed
for cluster communication (corosync, API, SSH) using this alias.

The user can overwrite these values in the cluster.fw alias
section. If you use a single host on a public network, it is better to
explicitly assign the local IP address

----
#  /etc/pve/firewall/cluster.fw
[ALIASES]
local_network 1.2.3.4 # use the single ip address
----

IP Sets
~~~~~~~

IP sets can be used to define groups of networks and hosts. You can
refer to them with `+name` in the firewall rules' `source` and `dest`
properties.

The following example allows HTTP traffic from the `management` IP
set.

 IN HTTP(ACCEPT) -source +management

Standard IP set `management`
^^^^^^^^^^^^^^^^^^^^^^^^^^^^

This IP set applies only to host firewalls (not VM firewalls).  Those
ips are allowed to do normal management tasks (PVE GUI, VNC, SPICE,
SSH).

The local cluster network is automatically added to this IP set (alias
`cluster_network`), to enable inter-host cluster
communication. (multicast,ssh,...)

----
# /etc/pve/firewall/cluster.fw

[IPSET management] 
192.168.2.10
192.168.2.10/24
----

Standard IP set 'blacklist'
^^^^^^^^^^^^^^^^^^^^^^^^^^^

Traffic from these ips is dropped by every host's and VM's firewall.

----
# /etc/pve/firewall/cluster.fw

[IPSET blacklist] 
77.240.159.182
213.87.123.0/24
----

[[ipfilter-section]]
Standard IP set 'ipfilter-net*'
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

These filters belong to a VM's network interface and are mainly used to prevent
IP spoofing. If such a set exists for an interface then any outgoing traffic
with a source IP not matching its interface's corresponding ipfilter set will
be dropped.

For containers with configured IP addresses these sets, if they exist (or are
activated via the general `IP Filter` option in the VM's firewall's 'options'
tab), implicitly contain the associated IP addresses.

For both virtual machines and containers they also implicitly contain the
standard MAC-derived IPv6 link-local address in order to allow the neighbor
discovery protocol to work.

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

[IPSET ipfilter-net0] # only allow specified IPs on net0
192.168.2.10
----

Services and Commands
~~~~~~~~~~~~~~~~~~~~~

The firewall runs two service daemons on each node:

* pvefw-logger: NFLOG daemon (ulogd replacement).
* pve-firewall: updates iptables rules

There is also a CLI command named 'pve-firewall', which can be used to
start and stop the firewall service:

 # pve-firewall start
 # pve-firewall stop

To get the status use:

 # pve-firewall status

The above command reads and compiles all firewall rules, so you will
see warnings if your firewall configuration contains any errors.

If you want to see the generated iptables rules you can use:

 # iptables-save

Tips and Tricks
~~~~~~~~~~~~~~~

How to allow FTP
^^^^^^^^^^^^^^^^

FTP is an old style protocol which uses port 21 and several other dynamic ports. So you
need a rule to accept port 21. In addition, you need to load the 'ip_conntrack_ftp' module.
So please run: 

 modprobe ip_conntrack_ftp

and add `ip_conntrack_ftp` to '/etc/modules' (so that it works after a reboot) .

Suricata IPS integration
^^^^^^^^^^^^^^^^^^^^^^^^

If you want to use the http://suricata-ids.org/[Suricata IPS]
(Intrusion Prevention System), it's possible.

Packets will be forwarded to the IPS only after the firewall ACCEPTed
them.

Rejected/Dropped firewall packets don't go to the IPS.

Install suricata on proxmox host:

----
# apt-get install suricata
# modprobe nfnetlink_queue  
----

Don't forget to add `nfnetlink_queue` to '/etc/modules' for next reboot.

Then, enable IPS for a specific VM with:

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

[OPTIONS]
ips: 1
ips_queues: 0
----

`ips_queues` will bind a specific cpu queue for this VM.

Available queues are defined in

----
# /etc/default/suricata
NFQUEUE=0
----


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Notes on IPv6
^^^^^^^^^^^^^

The firewall contains a few IPv6 specific options. One thing to note is that
IPv6 does not use the ARP protocol anymore, and instead uses NDP (Neighbor
Discovery Protocol) which works on IP level and thus needs IP addresses to
succeed. For this purpose link-local addresses derived from the interface's MAC
address are used. By default the 'NDP' option is enabled on both host and VM
level to allow neighbor discovery (NDP) packets to be sent and received.

Beside neighbor discovery NDP is also used for a couple of other things, like
autoconfiguration and advertising routers.

By default VMs are allowed to send out router solicitation messages (to query
for a router), and to receive router advetisement packets. This allows them to
use stateless auto configuration. On the other hand VMs cannot advertise
themselves as routers unless the 'Allow Router Advertisement' (`radv: 1`) option
is set.

As for the link local addresses required for NDP, there's also an 'IP Filter'
(`ipfilter: 1`) option which can be enabled which has the same effect as adding
an `ipfilter-net*` ipset for each of the VM's network interfaces containing the
corresponding link local addresses.  (See the
<<ipfilter-section,Standard IP set 'ipfilter-net*'>> section for details.)