illumos: manual page: svc.ipfd.8

SVC.IPFD(8) Maintenance Procedures SVC.IPFD(8)

NAME

svc.ipfd - IP Filter firewall monitoring daemon

SYNOPSIS

/lib/svc/bin/svc.ipfd

svc:/network/ipfilter:default

DESCRIPTION

The svc.ipfd daemon monitors actions on services that use firewall
configuration and initiates update services' IP Filter configuration. The
daemon allows the system to react to changes in system's firewall
configuration in an incremental fashion, at a per-service level.

A service's firewall policy is activated when it is enabled, deactivated
when it is disabled, and updated when its configuration property group is
modified. svc.ipfd monitors the services management facility (SMF)
repository for these actions and invokes the IP Filter rule-generation
process to carry out the service's firewall policy.

This daemon is started by the network/ipfilter service either through the
start or refresh method. Thus, the daemon inherits the environment
variables and credentials from the method and runs as root with all zone
privileges.

Firewall Static Configuration

A static definition describes a service's network resource configuration
that is used to generate service-specific IPF rules. The per-service
firewall_context property group contains a service's static definition,
similar to the inetd property group in inetd managed services. This
property group supports:

firewall_context/name

For non-inetd services. The IANA name or RPC name, equivalent to the
inetd/name property.

firewall_context/isrpc

For non-inetd services. A boolean property where a true value
indicates an RPC service, equivalent to the inetd/isrpc property. For
RPC services, the value of firewall_context/name is not an IANA name
but is either an RPC program number or name. See rpc(5).

Additionally, some services may require a mechanism to generate and
supply their own IPF rules. An optional property ipf_method, provides a
mechanism to allow such custom rule generation:

firewall_context/ipf_method

A command. Normally a script that generates IPF rules for a service.
The framework does not generate rules for services with this property
definition. Rather, the framework expects these services to provide
their own rules.

A service's ipf_method specifies a command that takes an additional
argument, its own fault management resource identifier (FMRI), and
generates the service's firewall rules and outputs those rules to stdout.
To generate rules for a service with the ipf_method property, the
framework execs the command specified in ipf_method, passing the service
FMRI as the additional argument, and stores the rules for that service by
redirecting the command output, the rules, to the service's rule file.
Because an ipf_method is exec'ed from the context of either the
network/ipfilter start or refresh method process, it inherits the
execution context and runs as root.

The service static configuration is delivered by the service developer
and not intended to be modified by users. These properties are only
modified upon installation of an updated service definition.

Firewall Policy Configuration

A per-service property group, firewall_config, stores the services'
firewall policy configuration. Because network/ipfilter:default is
responsible for two firewall policies, the Global Default and Global
Override system-wide policies (as explained in ipfilter(7)), it has two
property groups, firewall_config_default and firewall_config_override, to
store the respective system-wide policies.

Below are the properties, their possible values, and corresponding
semantics:

policy

The policy has the following modes:

none policy mode

No access restriction. For a global policy, this mode allows all
incoming traffic. For a service policy, this mode allows all
incoming traffic to its service.

deny policy mode

More restrictive than none. This mode allows incoming traffic
from all sources except those specified in the apply_to property.

allow policy mode

Most restrictive mode. This mode blocks incoming traffic from all
sources except those specified in the apply_to property.

block-policy

The block-policy property defines the handling of packets that are
blocked by the filter. It has the following modes:

none block-policy mode

Block by dropping packets.

return block-policy mode

Block by returning RST (for TCP) or ICMP messages (for other
protocols) to the sender of the blocked packets.

apply_to

A multi-value property listing IPv4 network source entities to
enforce the chosen policy mode. Packets coming from the entities
listed in apply_to property will be denied if policy is deny and
allowed if policy is allow. The syntax for possible values are:

host: host:IP "host:192.168.84.14"
subnet: network:IP/netmask "network:129.168.1.5/24"
ippool: pool:pool number "pool:77"
interface: if:interface_name "if:e1000g0"

apply_to_6

A multi-value property listing IPv6 network source entities to
enforce the chosen policy mode. Packets coming from the entities
listed in apply_to_6 property will be denied if policy is deny and
allowed if policy is allow. The syntax for possible values are:

host: host:IP "host:2001:DB8::12ff:fe34:5678"
subnet: network:IP/netmask "network:2001:DB8::/32"
ippool: pool:pool number "pool:77"
interface: if:interface_name "if:e1000g0"

exceptions

A multi-value property listing IPv4 network source entities to be
excluded from the apply_to list. For example, when deny policy is
applied to a subnet, exceptions can be made to some hosts in that
subnet by specifying them in the exceptions property. This property
has the same value syntax as apply_to property.

exceptions_6

A multi-value property listing IPv6 network source entities to be
excluded from the apply_to_6 list. For example, when deny policy is
applied to a subnet, exceptions can be made to some hosts in that
subnet by specifying them in the exceptions_6 property. This property
has the same value syntax as apply_to_6 property.

target

A multi-value property listing IPv4 network destination entities to
enforce the chosen policy mode. Packets directed to the destination
entities listed in target property will be denied if policy is deny
and allowed if policy is allow. This property has the same value
syntax as apply_to property, with the notable exception that
specifying network interfaces is not supported.

target_6

A multi-value property listing IPv6 network destination entities to
enforce the chosen policy mode. Packets directed to the destination
entities listed in target_6 property will be denied if policy is deny
and allowed if policy is allow. This property has the same value
syntax as apply_to_6 property, with the notable exception that
specifying network interfaces is not supported.

For individual network services only:

firewall_config/policy

A service's policy can also be set to use_global. Services with
use_global policy mode inherit the Global Default firewall policy.

firewall_config/block_policy

A service's block policy can also be set to use_global. Services with
use_global block policy mode inherit the Global Default firewall
block policy.

For the Global Default only:

firewall_config_default/policy

Global Default policy, firewall_config property group in
svc:/network/ipfilter:default, can also be set to custom. Users can
set policy to custom to use prepopulated IP Filter configuration, for
example, an existing IP Filter configuration or custom configurations
that cannot be provided by the framework. This Global Default-only
policy mode allows users to supply a text file containing the
complete set of IPF rules. When custom mode is selected, the
specified set of IPF rules is complete and the framework will not
generate IPF rules from configured firewall policies.

firewall_config_default/custom_policy_file

A file path to be used when Global Default policy is set to custom.
The file contains a set of IPF rules that provide the desired IP
Filter configuration. For example, users with existing IPF rules in
/etc/ipf/ipf.conf can execute the following commands to use the
existing rules:

1. Set custom policy:

# svccfg -s ipfilter:default setprop \
firewall_config_default/policy = astring: "custom"

2. Specify custom file:

# svccfg -s ipfilter:default setprop \
firewall_config_default/custom_policy_file = astring: \
"/etc/ipf/ipf.conf"

3. Refresh configuration:

# svcadm refresh ipfilter:default

firewall_config_default/open_ports

Non-service program requiring allowance of its incoming traffic can
request that the firewall allow traffic to its communication ports.
This multi-value property contains protocol and port(s) tuple in the
form:

"{tcp | udp}:{PORT | PORT-PORT}"

Initially, the system-wide policies are set to none and network services'
policies are set to use_global. Enabling network/ipfilter activates the
firewall with an empty set of IP Filter rules, since system-wide policy
is none and all services inherit that policy. To configure a more
restrictive policy, use svccfg(8) to modify network services and system-
wide policies.

A user configures firewall policy by modifying the service's
firewall_config property group. A new authorization,
solaris.smf.value.firewall.config, is created to allow delegation of the
firewall administration privilege to users. Users with Service Operator
privileges will need this new authorization to be able to configure
firewall policy.

Firewall Availability

During boot, a firewall is configured for enabled services prior to the
starting of those services. Thus, services are protected on boot. While
the system is running, administrative actions such as service restarting,
enabling, and refreshing may cause a brief service vulnerability during
which the service runs while its firewall is being configured.

svc.ipfd monitors a service's start and stop events and configures or
unconfigures a service's firewall at the same time that SMF is starting
or stopping the service. Because the two operations are simultaneous,
there is a possible window of exposure (less than a second) if the
service is started before its firewall configuration completed. RPC
services typically listen on ephemeral addresses, which are not known
until the services are actually running. Thus RPC services are subjected
to similar exposure since their firewalls are not configured until the
services are running.

Developer Documentation

Services providing remote capabilities are encouraged to participate in
the firewall framework to control network access to the service. While
framework integration is not mandatory, remote access to services that
are not integrated in the framework may not function correctly when a
system-wide policy is configured.

Integrating a service into the framework is as straightforward as
defining two additional property groups and their corresponding
properties in the service manifest. IP Filter rules are generated when a
user enables the service. In the non-trivial case of custom rule
generation, where a shell script is required, there are existing scripts
that can be used as examples.

The additional property groups, firewall_config and firewall_context,
stores firewall policy configuration and provides static firewall
definition, respectively. Below is a summary of new property groups and
properties and their appropriate default values.

Firewall policy configuration:

firewall_config

Access to the system is protected by a new authorization definition
and a user-defined property type. The new authorization should be
assigned to the property group value_authorization property in a way
such as:

<propval name='value_authorization' type='astring'
value='solaris.smf.value.firewall.config' />

A third party should follow the service symbol namespace convention
to generate a user-defined type. Sun-delivered services can use
com.sun,fw_configuration as the property type.

See "Firewall Policy Configuration," above, for more information.

firewall_config/policy

This property's initial value should be use_global since services, by
default, inherit the Global Default firewall policy.

firewall_config/apply_to

An empty property, this property has no initial value.

firewall_config/exceptions

An empty property, this property has no initial value.

Firewall static definition:

firewall_context

A third party should follow service symbol namespace convention to
generate a user-defined type, Sun delivered services can use
com.sun,fw_definition as the property type.

See "Firewall Static Configuration," above, for more information.

firewall_context/name

Service with well-known, IANA defined port, which can be obtained by
getservbyname(3SOCKET). The service's IANA name is stored in this
property. For RPC services, the RPC program number is stored in this
property.

firewall_context/isrpc

For RPC services, this property should be created with its value set
to true.

firewall_context/ipf_method

In general, the specified firewall policy is used to generate IP
Filter rules to the service's communication port, derived from the
firewall_context/name property. Services that do not have IANA-
defined ports and are not RPC services will need to generate their
own IP Filter rules. Services that generate their own rules may
choose not to have firewall_context/name and firewall_context/isrpc
properties. See the following services:

svc:/network/ftp:default
svc:/network/nfs/server:default
svc:/network/ntp:default

...and others with the ipf_method for guidance.

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