Description

Simple cookbook with LWRPs for managing iptables rules and policies.

Requirements

None, other than a system that supports iptables.

Platforms

The following platforms are supported and known to work:

• Debian (6.0 and later)
• RedHat (5.8 and later)
• CentOS (5.8 and later)

Other platforms that support iptables and the iptables-restore script are likely to work as well; if you use one, please let me know so that I can update the supported platforms list.

Attributes

This cookbook uses node attributes to track internal state when generating the iptables rules and policies. These attributes should not be overridden by roles, other recipes, etc.

Usage

Include the recipe simple_iptables somewhere in your run list, then use the LWRPs simple_iptables_rule and simple_iptables_policy in your recipes.

simple_iptables_rule Resource

Defines a single iptables rule, composed of a rule string (passed as-is to iptables), and a jump target. The name attribute defines an iptables chain that this rule will live in (and, thus, that other rules can jump to). For instance:

# Allow SSH
simple_iptables_rule "ssh" do
  rule "--proto tcp --dport 22"
  jump "ACCEPT"
end

For convenience, you may also specify an array of rule strings in a single LWRP invocation:

# Allow HTTP, HTTPS
simple_iptables_rule "http" do
  rule [ "--proto tcp --dport 80",
         "--proto tcp --dport 443" ]
  jump "ACCEPT"
end

Additionally, if you want to declare a module (such as log) you can define jump as false:

# Log
simple_iptables_rule "system" do
  rule "--match limit --limit 5/min --jump LOG --log-prefix \"iptables denied: \" --log-level 7"
  jump false
end

By default rules are added to the filter table but the nat table is also supported. For example:

# Tomcat redirects
simple_iptables_rule "tomcat" do
  table "nat"
  direction "PREROUTING"
  rule [ "--protocol tcp --dport 80 --jump REDIRECT --to-port 8080",
         "--protocol tcp --dport 443 --jump REDIRECT --to-port 8443" ]
  jump false
end

simple_iptables_policy Resource

Defines a default action for a given iptables chain. This is usually used to switch from a default-accept policy to a default-reject policy. For instance:

# Reject packets other than those explicitly allowed
simple_iptables_policy "INPUT" do
  policy "DROP"
end

As with the simple_iptables_rules resource, policies are applied to the filter table by default. You may change the target table to nat as follows:

# Reject packets other than those explicitly allowed
simple_iptables_policy "INPUT" do
  table "nat"
  policy "DROP"
end

Example

Suppose you had the following simple_iptables configuration:

# Reject packets other than those explicitly allowed
simple_iptables_policy "INPUT" do
  policy "DROP"
end

# The following rules define a "system" chain; chains
# are used as a convenient way of grouping rules together,
# for logical organization.

# Allow all traffic on the loopback device
simple_iptables_rule "system" do
  rule "--in-interface lo"
  jump "ACCEPT"
end

# Allow any established connections to continue, even
# if they would be in violation of other rules.
simple_iptables_rule "system" do
  rule "-m conntrack --ctstate ESTABLISHED,RELATED"
  jump "ACCEPT"
end

# Allow SSH
simple_iptables_rule "system" do
  rule "--proto tcp --dport 22"
  jump "ACCEPT"
end

# Allow HTTP, HTTPS
simple_iptables_rule "http" do
  rule [ "--proto tcp --dport 80",
         "--proto tcp --dport 443" ]
  jump "ACCEPT"
end

# Tomcat redirects
simple_iptables_rule "tomcat" do
  table "nat"
  direction "PREROUTING"
  rule [ "--protocol tcp --dport 80 --jump REDIRECT --to-port 8080",
         "--protocol tcp --dport 443 --jump REDIRECT --to-port 8443" ]
  jump false
end

This would generate a file /etc/iptables-rules with the contents:

# This file generated by Chef. Changes will be overwritten.
*nat
:PREROUTING ACCEPT [0:0]
:INPUT ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:POSTROUTING ACCEPT [0:0]
:tomcat - [0:0]
-A PREROUTING --jump tomcat
-A tomcat --protocol tcp --dport 80 --jump REDIRECT --to-port 8080
-A tomcat --protocol tcp --dport 443 --jump REDIRECT --to-port 8443
COMMIT
# Completed
# This file generated by Chef. Changes will be overwritten.
*filter
:INPUT DROP [0:0]
:FORWARD ACCEPT [0:0]
:OUTPUT ACCEPT [0:0]
:system - [0:0]
:http - [0:0]
-A INPUT --jump system
-A system --in-interface lo --jump ACCEPT
-A system -m conntrack --ctstate ESTABLISHED,RELATED --jump ACCEPT
-A system --proto tcp --dport 22 --jump ACCEPT
-A INPUT --jump http
-A http --proto tcp --dport 80 --jump ACCEPT
-A http --proto tcp --dport 443 --jump ACCEPT
COMMIT
# Completed

Which results in the following iptables configuration:

# iptables -L
Chain INPUT (policy DROP)
target     prot opt source               destination         
system     all  --  anywhere             anywhere            
http       all  --  anywhere             anywhere            

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain http (1 references)
target     prot opt source               destination         
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:http
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:https

Chain system (1 references)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            
ACCEPT     all  --  anywhere             anywhere             ctstate RELATED,ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:ssh

#iptables -L -t nat
Chain PREROUTING (policy ACCEPT)
target     prot opt source               destination         
tomcat     all  --  anywhere             anywhere            

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         

Chain POSTROUTING (policy ACCEPT)
target     prot opt source               destination         

Chain tomcat (1 references)
target     prot opt source               destination         
REDIRECT   tcp  --  anywhere             anywhere             tcp dpt:http redir ports 8080
REDIRECT   tcp  --  anywhere             anywhere             tcp dpt:https redir ports 8443

Changes

• 0.3.0 (March 5, 2013)
  • Added support for nat table (#10 - Nathan Mische)
  • Updated Gemfile for Travis-CI integration (#10 - Nathan Mische)
• 0.2.4 (Feb 13, 2013)
  • Fixed attribute precedence issues in Chef 11 (#9 - Warwick Poole)
  • Added name to metadata to satisfy recent foodcritic versions
• 0.2.3 (Nov 10, 2012)
  • Fixed a warning in Chef 11+ (#7 - Hector Castro)
• 0.2.2 (Oct 13, 2012)
  • Added support for logging module and other non-jump rules (#6 - phoolish)
• 0.2.1 (Aug 5, 2012)
  • Fixed a bug using simple_iptables with chef-solo (#5)
• 0.2.0 (Aug 1, 2012)
  • Allow an array of rules in simple_iptables_rule LWRP (Johannes Becker)
  • RedHat/CentOS compatibility (David Stainton)
  • Failing simple_iptables_rules now fail with a more helpful error message
• 0.1.2 (July 24, 2012)
  • Fixed examples in README (SchraderMJ11)
• 0.1.1 (May 22, 2012)
  • Added Travis-CI integration (Nathen Harvey)
  • Fixed foodcritic warnings (Nathen Harvey)
• 0.1.0 (May 12, 2012)
  • Initial release