Proxmox Firewall Rules

Proxmox Firewall Rules

Category : Knowledge

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proxmox logo gradProxmox uses various ports for communication between either a user and the server or between multiple servers in a cluster. You may need to proxy or port forward some of these ports for external access to Proxmox or, in more strict environments, add rules to allow inter machine communication.

For external access to Proxmox you will use either SSH, the web console or SPICE. The following ports are used for each of these services:

  • Web console: 8006 TCP – this is the console you open in your web browser to administer Proxmox. Note: VNC terminals will not work on this port alone.
  • VNC console: 5900 – 5999 TCP – this range of ports is used for the VNC console/ terminal. The reason there is a range is because each open session requires it’s own port meaning that you can have a total of 100 open VNC sessions at once.
  • SPICE: 3128 TCP – this is used if you use SPICE instead of the VNC console. SPICE requires a client to connect.
  • SSH: 22 TCP – this is required for accessing your Proxmox server using SSH.

An additional set of ports are required if you are using Proxmox in a cluster.

  • CMAN: 5404 and 5405 UDP – this is the cluster manager for the Proxmox cluster.

GlusterFS firewall rules

Category : How-to

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gluster-orange-antIf you can, your storage servers should be in a secure zone in your network removing the need to firewall each machine. Inspecting packets incurs an overhead, not something you need on a high performance file server so you should not run a file server in an insecure zone. If you are using GlusterFS behind a firewall you will need to allow several ports for GlusterFS to communicate with clients and other servers. The following ports are all TCP:

Note: the brick ports have changed since version 3.4. 

  • 24007 – Gluster Daemon
  • 24008 – Management
  • 24009 and greater (GlusterFS versions less than 3.4) OR
  • 49152 (GlusterFS versions 3.4 and later) – Each brick for every volume on your host requires it’s own port. For every new brick, one new port will be used starting at 24009 for GlusterFS versions below 3.4 and 49152 for version 3.4 and above. If you have one volume with two bricks, you will need to open 24009 – 24010 (or 49152 – 49153).
  • 38465 – 38467 – this is required if you by the Gluster NFS service.

The following ports are TCP and UDP:

  • 111 – portmapper

iptables cheat sheet

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Here are a few handy commands for using iptables. They are tailored for an OpenVZ container with a venet network interface but can easily be adapted to use your interface by replacing venet0 with your network interface.

For setting up iptables in an openVZ this blog post.

iptables console

Remove existing rules

You can easily delete all existing rules in iptables. Be careful using this command, there is no going back unless you have backed up your rules.

iptables -F

Backup and restore

Backup to file

Rules can easily be saved to an external file for backups or outputting for version control. This will save the rules to /etc/iptables.rules.

iptables-save -c > /etc/iptables.rules

Restore from file

Saved settings can be restored with the following command:

iptables-restore > /etc/iptables.rules

Change the default policy

The default policy can be changed to specify what should happen to traffic which doesn’t have a rule to explicitly define what to do. You can specify to ACCEPT, REJECT or DROP for INPUT, FORWARD and OUTPUT.

Change OUTPUT to ACCEPT

iptables -P OUTPUT ACCEPT

Change INPUT to DROP

iptables -P INPUT DROP

Apply the catchall rule

You can add a rule to the bottom of the rule book to choose what to do with traffic which doesn’t match any other rule. A common use would be to add a DROP as the last rule to drop any traffic which isn’t explicitly allowed by an earlier rule. You can specify to ACCEPT, REJECT or DROP for INPUT, FORWARD and OUTPUT as well as an interface.

ACCEPT INPUT on interface lo

iptables -A INPUT -i lo -j ACCEPT

BLOCK INPUT on interface venet0

iptables -A INPUT -i venet0 -j DROP

List active rules

You can list the active rules with -L, and -v for information on packets affected.

iptables -L -v

Enable established connections rule

Already established connections will not be affected by adding this inbound rule. Traffic affected by other outbound rules will also be honoured. If you add this rule, you won’t likely need to specify inbound rules for many outbound rules.

iptables -A INPUT -i venet0 -m state --state RELATED,ESTABLISHED -j ACCEPT

Adding new rules

New rules can be added to control how traffic passes through an interface. If you have not used the Established connections rule then you will also need to add an outgoing rule. If you do use the Established connections rule then you will only need the top command in each of the below headings.

Add rule for port 80 – such as Apache

iptables -A INPUT -i venet0 -p tcp --dport 80 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o venet0 -p tcp --sport 80 -m state --state ESTABLISHED -j ACCEPT

Add rule for port 22 – SSH outbound connections

iptables -A OUTPUT -o venet0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i venet0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

Add rule for 53 – DNS outbound

iptables -A OUTPUT -o venet0 -p udp -o eth0 --dport 53 -j ACCEPT
iptables -A INPUT -i venet0-p udp -i eth0 --sport 53 -j ACCEPT

Add rule for port 22 – SSH inbound connections

iptables -A INPUT -i venet0 -p tcp --dport 22 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -o venet0 -p tcp --sport 22 -m state --state ESTABLISHED -j ACCEPT

Add rule for outgoing http/ https

iptables -A OUTPUT -o venet0 -p tcp -m multiport --dport 80,443 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -i venet0 -p tcp -m multiport --sports 80,443 -m state --state ESTABLISHED -j ACCEPT

Add rule for ping from remote to local

iptables -A INPUT -i venet0 -p icmp --icmp-type echo-request -j ACCEPT
iptables -A OUTPUT -o ventet -p icmp --icmp-type echo-reply -j ACCEPT

 Add rule for ping from local to remote

iptables -A OUTPUT -o venet0 -p icmp --icmp-type echo-request -j ACCEPT
iptables -A INPUT -i venet0 -p icmp --icmp-type echo-reply -j ACCEPT

Delete rule

The easiest way to remove a rule is to delete it by it’s rule position in the list. To find out the rules position run iptables -L with the line-number argument. The below command is to delete an INPUT command however you can easily change INPUT to OUTPUT as required.

iptables -L INPUT --line-numbers

Then run the delete command for the relevent direction. This will delete the 7th inbound rule.

iptables -D INPUT 7

Example deleting rule 1 for INPUT:

# iptables -L INPUT --line-numbers
Chain INPUT (policy DROP)
num  target     prot opt source               destination
1    ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:ssh state NEW,ESTABLISHED
2    ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
3    ACCEPT     icmp --  anywhere             anywhere             icmp echo-reply
4    ACCEPT     icmp --  anywhere             anywhere             icmp echo-request

# iptables -D INPUT 1

# iptables -L INPUT --line-numbers
Chain INPUT (policy DROP)
num  target     prot opt source               destination
1    ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
2    ACCEPT     icmp --  anywhere             anywhere             icmp echo-reply
3    ACCEPT     icmp --  anywhere             anywhere             icmp echo-request

 

Let me know in the comments if you think anything is missing.


iptables in a Ubuntu OpenVZ container

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proxmox logo gradIf you need a software firewall to shield containers on a Proxmox stack, you should always use a firewall on the host to decide what traffic is allowed for each container. This brings some obvious benefits such as it’s centrally managed – one configuration location for all containers on the node, and security as a compromised container cannot change firewall settings.

However, in Proxmox 3.0+ you can use iptables in a container which also has it’s own benefits under certain circumstances. For example, you can test firewall rules for a new development container without risking other containers on the same host, and you don’t need to give people access to the host to modify the rules.

I have tried iptables using a Ubuntu 12.04 container template. It works as expected but requires some setup on both the guest container and the Proxmox host.

Setup

Proxmox – steps to perform on the Proxmox host

You will need to enable containers access to the required kernel modules. To do this, edit the vz config file:

vi /etc/vz/vz.conf

And edit the IPTABLES= line as below.

IPTABLES="ipt_REJECT ipt_tos ipt_limit ipt_multiport iptable_filter iptable_mangle ipt_TCPMSS ipt_tcpmss ipt_ttl ipt_length ipt_state"

Make sure the required modules are loaded by running the following in a console window as root:

modprobe xt_state
modprobe xt_tcpudp
modprobe ip_conntrack

 Container – steps to perform in the Ubuntu container

First, you need a console window in the host. Either use the GUI console window or use vzctl enter [VMID] to login to the container.

Install iptables using apt-get.

apt-get install iptables

Any changes you make to iptables, such as adding new rules, will be lost each time the service is restarted. This is obviously not ideal as all the rules will be lost every time the container reboots. To get round this we need to add a script to save the rules each time the network interface goes down, and one to load the rules when the interface starts up.

Create an iptables script to run when the network is started:

vi /etc/network/if-pre-up.d/iptables

And add the below script to load the rules into iptables:

#!/bin/sh
iptables-restore < /etc/iptables.rules
exit 0

And when the network goes down:

vi /etc/network/if-post-down.d/iptables

To save the rules:

#!/bin/sh
iptables-save -c > /etc/iptables.rules
exit 0

After your network is restarted, the current rules will be saved to /etc/iptables.rules. To add new rules, you can edit this file directly and load the settings or you can use the iptables commands to create the rules you require. More about that in my iptables cheat sheet.


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