pve-docs/pve-firewall.adoc

[[chapter_pve_firewall]]
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pve-firewall(8)
===============
:pve-toplevel:

NAME
----

pve-firewall - PVE Firewall Daemon


SYNOPSIS
--------

include::pve-firewall.8-synopsis.adoc[]


DESCRIPTION
-----------
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{pve} Firewall
==============
:pve-toplevel:
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:title: Firewall
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{pve} Firewall provides an easy way to protect your IT
infrastructure. You can 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 to make that task easier.

While all configuration is stored on the cluster file system, the
`iptables`-based firewall service 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.

The firewall has full support for IPv4 and IPv6. IPv6 support is fully
transparent, and we filter traffic for both protocols by default. So
there is no need to maintain a different set of rules for IPv6.


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.


Configuration Files
-------------------

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 changes.

You can configure anything using the GUI (i.e. *Datacenter* -> *Firewall*,
or on a *Node* -> *Firewall*), or you can edit the configuration files
directly using your preferred editor.

Firewall configuration files contain sections of key-value
pairs. Lines beginning with a `#` and blank lines are considered
comments. Sections start with a header line containing the section
name enclosed in `[` and `]`.


[[pve_firewall_cluster_wide_setup]]
Cluster Wide Setup
~~~~~~~~~~~~~~~~~~

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

The configuration can contain the following sections:

`[OPTIONS]`::

This is used to set cluster-wide firewall options.

include::pve-firewall-cluster-opts.adoc[]

`[RULES]`::

This sections contains cluster-wide firewall rules for all nodes.

`[IPSET <name>]`::

Cluster wide IP set definitions.

`[GROUP <name>]`::

Cluster wide security group definitions.

`[ALIASES]`::

Cluster wide Alias definitions.


Enabling the Firewall
^^^^^^^^^^^^^^^^^^^^^

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
----

IMPORTANT: If you enable the firewall, traffic to all hosts is blocked by
default. Only exceptions is WebGUI(8006) and ssh(22) from your local
network.

If you want to administrate your {pve} hosts from remote, you
need to create rules to allow traffic from those remote IPs to the web
GUI (port 8006). You may also want to allow ssh (port 22), and maybe
SPICE (port 3128).

TIP: Please open a SSH connection to one of your {PVE} hosts before
enabling the firewall. That way you still have access to the host if
something goes wrong .

To simplify that task, you can instead create an IPSet called
``management'', and add all remote IPs there. This creates all required
firewall rules to access the GUI from remote.


[[pve_firewall_host_specific_configuration]]
Host Specific Configuration
~~~~~~~~~~~~~~~~~~~~~~~~~~~

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. The configuration can contain the following sections:

`[OPTIONS]`::

This is used to set host related firewall options.

include::pve-firewall-host-opts.adoc[]

`[RULES]`::

This sections contains host specific firewall rules.

[[pve_firewall_vm_container_configuration]]
VM/Container Configuration
~~~~~~~~~~~~~~~~~~~~~~~~~~

VM firewall configuration is read from:

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

and contains the following data:

`[OPTIONS]`::

This is used to set VM/Container related firewall options.

include::pve-firewall-vm-opts.adoc[]

`[RULES]`::

This sections contains VM/Container firewall rules.

`[IPSET <name>]`::

IP set definitions.

`[ALIASES]`::

IP Alias definitions.


Enabling the Firewall for VMs and Containers
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Each virtual network device has its own firewall enable flag. So you
can selectively enable the firewall for each interface. This is
required in addition to the general firewall `enable` option.


Firewall Rules
--------------

Firewall rules consists of a direction (`IN` or `OUT`) and an
action (`ACCEPT`, `DENY`, `REJECT`). You can also specify a macro
name. Macros contain predefined sets of rules and options. Rules can be
disabled by prefixing them with `|`.

.Firewall rules syntax
----
[RULES]

DIRECTION ACTION [OPTIONS]
|DIRECTION ACTION [OPTIONS] # disabled rule

DIRECTION MACRO(ACTION) [OPTIONS] # use predefined macro
----

The following options can be used to refine rule matches. 

include::pve-firewall-rules-opts.adoc[]

Here are some examples:

----
[RULES]
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

IN  DROP # drop all incoming packages
OUT ACCEPT # accept all outgoing packages
----


[[pve_firewall_security_groups]]
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
----

[[pve_firewall_ip_aliases]]
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
----

[[pve_firewall_ip_sets]]
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
----


[[pve_firewall_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

[[pve_firewall_default_rules]]
Default firewall rules
----------------------

The following traffic is filtered by the default firewall configuration:

Datacenter incoming/outgoing DROP/REJECT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

If the input or output policy for the firewall is set to DROP or REJECT, the
following traffic is still allowed for all {pve} hosts in the cluster:

* traffic over the loopback interface
* already established connections
* traffic using the IGMP protocol
* TCP traffic from management hosts to port 8006 in order to allow access to
  the web interface
* TCP traffic from management hosts to the port range 5900 to 5999 allowing
  traffic for the VNC web console
* TCP traffic from management hosts to port 3128 for connections to the SPICE
  proxy
* TCP traffic from management hosts to port 22 to allow ssh access
* UDP traffic in the cluster network to port 5404 and 5405 for corosync
* UDP multicast traffic in the cluster network
* ICMP traffic type 3 (Destination Unreachable), 4 (congestion control) or 11
  (Time Exceeded)

The following traffic is dropped, but not logged even with logging enabled:

* TCP connections with invalid connection state
* Broadcast, multicast and anycast traffic not related to corosync, i.e., not
  coming through port 5404 or 5405
* TCP traffic to port 43
* UDP traffic to ports 135 and 445
* UDP traffic to the port range 137 to 139
* UDP traffic form source port 137 to port range 1024 to 65535
* UDP traffic to port 1900
* TCP traffic to port 135, 139 and 445
* UDP traffic originating from source port 53

The rest of the traffic is dropped or rejected, respectively, and also logged.
This may vary depending on the additional options enabled in
*Firewall* -> *Options*, such as NDP, SMURFS and TCP flag filtering.

[[pve_firewall_iptables_inspect]]
Please inspect the output of the

----
 # iptables-save
----

system command to see the firewall chains and rules active on your system.
This output is also included in a `System Report`, accessible over a node's
subscription tab in the web GUI, or through the `pvereport` command line tool.

VM/CT incoming/outgoing DROP/REJECT
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

This drops or rejects all the traffic to the VMs, with some exceptions for
DHCP, NDP, Router Advertisement, MAC and IP filtering depending on the set
configuration.  The same rules for dropping/rejecting packets are inherited
from the datacenter, while the exceptions for accepted incoming/outgoing
traffic of the host do not apply.

Again, you can use xref:pve_firewall_iptables_inspect[iptables-save (see above)]
to inspect all rules and chains applied.

Logging of firewall rules
-------------------------

By default, all logging of traffic filtered by the firewall rules is disabled.
To enable logging, the `loglevel` for incoming and/or outgoing traffic has to be
set in *Firewall* -> *Options*. This can be done for the host as well as for the
VM/CT firewall individually. By this, logging of {PVE}'s standard firewall rules
is enabled and the output can be observed in *Firewall* -> *Log*.
Further, only some dropped or rejected packets are logged for the standard rules
(see xref:pve_firewall_default_rules[default firewall rules]).

`loglevel` does not affect how much of the filtered traffic is logged. It
changes a `LOGID` appended as prefix to the log output for easier filtering and
post-processing.

`loglevel` is one of the following flags:

[[pve_firewall_log_levels]]
[width="25%", options="header"]
|===================
| loglevel | LOGID
| nolog    | --
| emerg    | 0
| alert    | 1
| crit     | 2
| err      | 3
| warning  | 4
| notice   | 5
| info     | 6
| debug    | 7
|===================

A typical firewall log output looks like this:

----
VMID LOGID CHAIN TIMESTAMP POLICY: PACKET_DETAILS
----

In case of the host firewall, `VMID` is equal to 0.


Logging of user defined firewall rules
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In order to log packets filtered by user-defined firewall rules, it is possible
to set a log-level parameter for each rule individually.
This allows to log in a fine grained manner and independent of the log-level
defined for the standard rules in *Firewall* -> *Options*.

While the `loglevel` for each individual rule can be defined or changed easily
in the WebUI during creation or modification of the rule, it is possible to set
this also via the corresponding `pvesh` API calls.

Further, the log-level can also be set via the firewall configuration file by
appending a `-log <loglevel>` to the selected rule (see
xref:pve_firewall_log_levels[possible log-levels]).

For example, the following two are ident:

----
IN REJECT -p icmp -log nolog
IN REJECT -p icmp
----

whereas

----
IN REJECT -p icmp -log debug
----

produces a log output flagged with the `debug` level.


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 https://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
----


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
auto-configuration and advertising routers.

By default VMs are allowed to send out router solicitation messages (to query
for a router), and to receive router advertisement 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
<<pve_firewall_ipfilter_section,Standard IP set `ipfilter-net*`>> section for details.)


Ports used by {pve}
-------------------

* Web interface: 8006 (TCP, HTTP/1.1 over TLS)
* VNC Web console: 5900-5999 (TCP, WebSocket)
* SPICE proxy: 3128 (TCP)
* sshd (used for cluster actions): 22 (TCP)
* rpcbind: 111 (UDP)
* sendmail: 25 (TCP, outgoing)
* corosync cluster traffic: 5404, 5405 UDP
* live migration (VM memory and local-disk data): 60000-60050 (TCP)

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Macro Definitions
-----------------

include::pve-firewall-macros.adoc[]


include::pve-copyright.adoc[]

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