Proxmox VE Firewall

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Introduction

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.

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

Ports

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

BEWARE that proxmox < 3.4 has no default management rules active, so since default incoming policy is DROP, you have to explicitly add tcp ACCEPT rules for port 22 and 8006 before activating firewall!

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 firewall for qemu guest and openvz veth

For qemu guests, linux containers and openvz veth interfaces, you need to enable the firewall on the virtual network interface configuration.

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 group a 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 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 in a vm firewall 

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

[RULES]
GROUP webserver


IP Aliases

IP Aliases allows you to associate IP addresses of Networks with a name. You can 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).

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 

# --- example: /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 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 IPSET 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 those ips is dropped in all hosts' and VMs' firewalls. 



/etc/pve/firewall/cluster.fw

[IPSET blacklist] 
77.240.159.182
213.87.123.0/24

Standard IP set 'ipfilter'

This ipset is used to prevent ip spoofing 

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

qemu interface 

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

openvz veth interface 

[IPSET ipfilter-eth0] # only allow specified IPs on veth eth0
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

Howto 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 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:

  1. apt-get install suricata

Then, enable IPS for a specific vm


/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

Video Tutorials

  • tbd.
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