Managing Packet Filtering Rule Sets for IP Filter

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IP Filter allows both active and inactive packet filtering rule sets to reside in the kernel. The active rule set determines what filtering is being done on incoming packets and outgoing packets. The inactive rule set also stores rules. These rules are not used unless you make the inactive rule set the active rule set. You can manage, view, and modify both active and inactive packet filtering rule sets.

Note - The following procedures provide examples for IPv4 networks. For IPv6 packets, use the –6 option, as described in Step 2 of How to Display IP Filter Service Defaults.

How to View the Active Packet Filtering Rule Set

Before You Begin

You must become an administrator who is assigned the IP Filter Management rights profile. For more information, see Using Your Assigned Administrative Rights in Securing Users and Processes in Oracle Solaris 11.3.

View the active packet filtering rule set.

The following example shows output from the active packet filtering rule set that is loaded in the kernel.

# ipfstat -io
empty list for ipfilter(out)
pass in quick on net1 from 198.51.100.0/27 to any
pass in all
block in on net1 from 198.51.100.10/27 to any

How to View the Inactive Packet Filtering Rule Set

Before You Begin

View the inactive packet filtering rule set.
The following example shows output from the inactive packet filtering rule set.
```
# ipfstat -I -io
pass out quick on net1 all
pass in quick on net1 all
```

How to Activate a Different or Updated Packet Filtering Rule Set

Use the following procedure if you want to perform either of the following tasks:

Activate a packet filtering rule set other than the one that is currently in use by IP Filter.
Reload the same filtering rule set that has been newly updated.

Before You Begin

Choose one of the following steps:
- Create a new rule set in a separate file if you want to activate an entirely different rule set.
- Update the current rule set in your configuration file.
Remove the current rule set and load the new rule set.
```
# ipf -Fa -f filename
```
The rules in filename replace the active rule set.

Note - Do not use commands such as ipf -D or svcadm restart to load the updated rule set. Such commands expose your network because they disable the firewall before loading the new rule set.

Example 9 Activating a Different Packet Filtering Rule Set

The following example shows how to replace one packet filtering rule set with a different rule set.

# ipfstat -io
empty list for ipfilter(out)
pass in quick on net0 all
# ipf -Fa -f /etc/ipf/ipfnew.conf
# ipfstat -io
empty list for ipfilter(out)
block in log quick from 192.0.2.0/27 to any

Example 10 Reloading an Updated Packet Filtering Rule Set

The following example shows how to reload a packet filtering rule set that is currently active and which is then updated.

Optionally, list the active rule set.

# ipfstat -io 
empty list for ipfilter (out)
block in log quick from 192.0.2.0/27 to any

Then, edit the /etc/ipf/myorg.ipf.conf configuration file, refresh the service, and list the active rule set again.

# svcadm refresh network/ipfilter
# ipfstat -io
empty list for ipfilter (out)
block in log quick from 192.0.2.0/27 to any
block in quick on net1 from 198.51.100.64/27 to any

How to Remove a Packet Filtering Rule Set

Before You Begin

Remove the rule set.
```
# ipf -F [a|i|o]
```
–a

Removes all filtering rules from the rule set.

–i

Removes the filtering rules for incoming packets.

–o

Removes the filtering rules for outgoing packets.

Example 11 Removing a Packet Filtering Rule Set

The following example shows how to remove all filtering rules from the active filtering rule set.

# ipfstat -io
block out log on net0 all
block in log quick from 192.0.2.0/27 to any
# ipf -Fa
# ipfstat -io
empty list for ipfilter(out)
empty list for ipfilter(in)

How to Append Rules to the Active Packet Filtering Rule Set

Appending rules to an existing rule set can be useful when testing or troubleshooting. The IP Filter service remains enabled when the rules are added. However, when the service is refreshed, restarted, or enabled, the rules are lost, unless they exist in files that are a property of the IP Filter service.

Before You Begin

Use one of the following methods to append rules to the active rule set:
- Append rules to the rule set at the command line using the ipf -f - command.
```
# echo "block in on net1 proto tcp from 192.0.2.64/27 to any" | ipf -f -
```
  These appended rules are not part of IP Filter configuration when the service is refreshed, restarted, or enabled.
- Perform the following commands:
  1. Create a rule set in a file of your choice.
  2. Add the rules that you have created to the active rule set.
```
# ipf -f filename
```
    The rules in filename are added to the end of the active rule set. Because IP Filter uses a "last matching rule" algorithm, the added rules determine filtering priorities, unless you use the quick keyword. If the packet matches a rule containing the quick keyword, the action for that rule is taken, and no subsequent rules are checked.
If filename is the value of one of the IP Filter configuration file properties, then the rules are reloaded when the service is enabled, restarted, or refreshed. Otherwise, the appended rules provide a temporary rule set.

Example 12 Appending Rules to the Active Packet Filtering Rule Set

The following example shows how to add a rule to the active packet filtering rule set from the command line.

# ipfstat -io
empty list for ipfilter(out)
block in log quick from 192.0.2.0/27 to any
# echo "block in on net1 proto tcp from 192.0.2.64/27 to any" | ipf -f -
# ipfstat -io
empty list for ipfilter(out)
block in log quick from 192.0.2.0/27 to any
block in on net1 proto tcp from 192.0.2.64/27 to any

How to Append Rules to the Inactive Packet Filtering Rule Set

Creating an inactive rule set in the kernel can be useful when testing or troubleshooting. The rule set can be switched with the active rule set without stopping the IP Filter service. However, when the service is refreshed, restarted, or enabled, the inactive rule set must be added.

Before You Begin

Create a rule set in a file of your choice.
Add the rules that you have created to the inactive rule set.
```
# ipf -I -f filename
```
The rules in filename are added to the end of the inactive rule set. Because IP Filter uses a "last matching rule" algorithm, the added rules determine filtering priorities, unless you use the quick keyword. If the packet matches a rule containing the quick keyword, the action for that rule is taken, and no subsequent rules are checked.

Example 13 Appending Rules to the Inactive Rule Set

The following example shows how to add a rule to the inactive rule set from a file.

# ipfstat -I -io
pass out quick on net1 all
pass in quick on net1 all
# ipf -I -f /etc/ipf/ipftrial.conf
# ipfstat -I -io
pass out quick on net1 all
pass in quick on net1 all
block in log quick from 192.0.2.0/27 to any

How to Switch Between Active and Inactive Packet Filtering Rule Sets

Switching to a different rule set in the kernel can be useful when testing or troubleshooting. The rule set can be made active without stopping the IP Filter service.

Before You Begin

Switch the active and inactive rule sets.
```
# ipf -s
```
This command enables you to switch between the active and inactive rule sets in the kernel. Note that if the inactive rule set is empty, there is no packet filtering.

Note - When the IP Filter service is refreshed, restarted, or enabled, the rules that are in files that are properties of the IP Filter service are restored. The inactive rule set is not restored.

Example 14 Switching Between the Active and Inactive Packet Filtering Rule Sets

The following example shows how using the ipf -s command results in the inactive rule set becoming the active rule set and the active rule set becoming the inactive rule set.

Before running the ipf -s command, the output from the ipfstat -I -io command shows the rules in the inactive rule set. The output from the ipfstat -io command shows the rules in the active rule set.

# ipfstat -io
empty list for ipfilter(out)
block in log quick from 192.0.2.0/27 to any
block in on net1 proto tcp from 192.0.2.64/27 to any
# ipfstat -I -io
pass out quick on net1 all
pass in quick on net1 all
block in log quick from 192.0.2.0/27 to any

After running the ipf -s command, the output from the ipfstat -I -io and the ipfstat -io command show that the content of the two rules sets have switched.

# ipf -s
Set 1 now inactive
# ipfstat -io
pass out quick on net1 all
pass in quick on net1 all
block in log quick from 192.0.2.0/27 to any
# ipfstat -I -io
empty list for inactive ipfilter(out)
block in log quick from 192.0.2.0/27 to any
block in on net1 proto tcp from 192.0.2.64/27 to any

How to Remove an Inactive Packet Filtering Rule Set From the Kernel

Before You Begin

Specify the inactive rule set in the "flush all" command.
```
# ipf -I -Fa
```
Note - If you subsequently run ipf -s, the empty inactive rule set will become the active rule set. An empty active rule set means that no filtering will be done.

Example 15 Removing an Inactive Packet Filtering Rule Set From the Kernel

The following example shows how to flush the inactive packet filtering rule set so that all rules have been removed.

# ipfstat -I -io
empty list for inactive ipfilter(out)
block in log quick from 192.0.2.0/27 to any
block in on net1 proto tcp from 192.0.2.64/27 to any
# ipf -I -Fa
# ipfstat -I -io
empty list for inactive ipfilter(out)
empty list for inactive ipfilter(in)