Template:Networking rutos manual firewall

Summary

{{{name}}} devices use a standard Linux iptables package as its firewall, which uses routing chains and policies to facilitate control over inbound and outbound traffic. This chapter is an overview of the Firewall section for {{{name}}} devices.

If you're having trouble finding this page or some of the parameters described here on your device's WebUI, you should turn on "Advanced WebUI" mode. You can do that by clicking the "Advanced" button, located at the top of the WebUI.

General settings

The General Settings section is used to configure the main policies of the device's firewall. The figure below is an example of the General Settings section and the table below provides information on the fields contained in that section:

Field	Value	Description
Enable SYN flood protection	off | on; Default: on	Enables protection from SYN flood type attacks. A SYN flood is a type of denial-of-service (DOS) attack where an attacker sends bursts of SYN requests in an attempt to make the target host machine consume enough resources and become unresponsive.
Drop invalid packets	off | on; Default: off	If enabled, a "Drop" action will be performed on packets that are determined to be invalid.
Input	Reject | Drop | Accept; Default: Accept	Default action* of the INPUT chain if a packet does not match any existing rule on that chain.
Output	Reject | Drop | Accept; Default: Accept	Default action* of the OUTPUT chain if a packet does not match any existing rule on that chain.
Forward	Reject | Drop | Accept; Default: Reject	Default action* of the FORWARD chain if a packet does not match any existing rule on that chain.

* When a packet goes through a firewall chain it is matched against all the rules of that specific chain. If no rule matches said packet, an according Action (Drop, Reject or Accept) is performed:

• Accept – packet gets to continue to the next chain.
• Drop – packet is stopped and deleted.
• Reject – packet is stopped, deleted and, differently from Drop, a message of rejection is sent to the source from which the packet came.

Zones

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The Zones section is used to manage default traffic forwarding policies between different device zones. The figure below is an example of the Zones section and the table below provides information on the fields contained in that section:

[[File::Networking_rutx_manual_firewall_general_settings_zones_v1.png]]

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You can change a zone's settings from this page by interacting with entries in the zones table. For a more in-depth configuration click the button that looks like a pencil next to a zone:

Zones: general settings

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Field	Value	Description
Name	string; default: newzone	A custom name for the zone. Used for easier management purposes.
Input	Reject | Drop | Accept; Default: Accept	Default policy for traffic entering the zone.
Output	Reject | Drop | Accept; Default: Accept	Default policy for traffic originating from and leaving the zone.
Forward	Reject | Drop | Accept; Default: Reject	Default policy for traffic forwarded between the networks belonging to the zone.
Masquerading	off | on; default: off	Turns Masquerading off or on. MASQUERADE is an iptables target that can be used instead of the SNAT (source NAT) target when the external IP of the network interface is not known at the moment of writing the rule (when the interface gets the external IP dynamically).
MSS clamping	off | on; default: off	Turns MSS clamping off or on. MSS clamping is a workaround used to change the maximum segment size (MSS) of all TCP connections passing through links with an MTU lower than the Ethernet default of 1500.
Covered networks	name of interface; default: none	Network or networks that belong to the zone.

Zones: advanced settings

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Field	Value	Description
Restrict to address family	IPv4 and IPv6 | IPv4 only | IPv6 only; default: IPv4 and IPv6	IP address family to which to rule will apply.
Restrict Masquerading to given source subnets	network/subnet; default: none	Applies Masquerading only to the specified source network/subnet.
Restrict Masquerading to given destinations subnets	network/subnet; default: none	Applies Masquerading only to the specified destination network/subnet.
Force connection tracking	off | on; default: off	Always maintains connection state (NEW, ESTABLISHED, RELATED) information.
Enable logging on this zone	off | on; default: off	Logs packets that hit this rule.
Limit log messages	integer/minute; default: none	Limit how many messages can be logged in the span of 1 minute. For example, to log 50 packets per minute use: 50/minute.

Zones: inter-zone forwarding

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The Inter-zone forwarding options control the forwarding policies between the currently edited zone and other zones.

Field	Value	Description
Allow forward to destination zones	zone(s); default: none	Allows forward traffic to specified destination zones. Destination zones cover forwarded traffic originating from this source zone.
Allow forward from source zones	zone(s); default: none	Allows forward traffic to specified source zones. Source zones match forwarded traffic originating from other zones that is targeted at this zone.

Port forwards

Port forwarding is a way of redirecting an incoming connection to another IP address, port or the combination of both:

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The Port forwards table displays configured port forwarding rules currently configured on the device.

New port forward

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The New port forward section is used to quickly add additional port forwarding rules. The figure below is an example of the New port forward section and the table below provides information on the fields contained in that section:

Field	Value	Description
Name	string; default: none	Name of the rule. This is used for easier management purposes.
Protocol	TCP+UDP | TCP | UDP | Other; default: TCP+UDP	Specifies to which protocols the rule should apply.
External zone	firewall zone name; default: wan	The zone to which hosts will be connecting.
External port	integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none	The port number to which hosts will be connecting.
Internal zone	firewall zone name; default: lan	The zone to which the incoming connection will be redirected.
Internal IP address	ip; default: none	The IP address to which the incoming connection will be redirected.
Internal port	integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none	The port number to which the incoming connection will be redirected.

Port forwards configuration

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While the New port forward section provides the possibility to add port forwarding rules fast, it does not contain all possible configuration options to customize a rule. In order to create a more complicated rule, add one using the New port forward section and click the button that looks like a pencil next to it:

You will be redirected to that rule's configuration page:

Field	Value	Description
Enable	off | on ; default: on	Turns the rule on or off
Name	string; default: none	Name of the rule. This is used for easier management purposes.
Protocol	TCP+UDP | TCP | UDP | Other; default: TCP+UDP	Specifies to which protocols the rule should apply.
Source zone	firewall zone name; default: wan	The zone to which the third party will be connecting. (Same thing as "External zone" in the New port forward section.)
Source MAC address	mac; default: none	MAC address(es) of connecting hosts. The rule will apply only to hosts that match MAC addresses specified in this field. Leave empty to make the rule skip MAC address matching.
Source IP address	ip | ip/netmask; default: any	IP address or network segment used by connecting hosts. The rule will apply only to hosts that connect from IP addresses specified in this field. To specify a network segment instead of one IP address, add a forward slash followed by the netmask length after the network indication (for example, 10.0.0.0/8).
Source port	integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none	Port number(s) used by the connecting host. The rule will match the source port used by the connecting host with the port number(s) specified in this field. Leave empty to make the rule skip source port matching.
External IP address	ip | ip/netmask; default: any	IP address or network segment to which hosts will be connecting. The rule will apply only to hosts that connect to IP addresses specified in this field. To specify a subnet instead of one IP, add a forward slash followed by the netmask length after the network indication (for example, 10.0.0.0/8).
External port	integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none	Port number(s) to which hosts will be connecting. The rule will apply only to hosts that connect to the port number(s) specified in this field. Leave empty to make the rule skip external port matching.
Internal zone	firewall zone name; default: lan	The zone to which the incoming connection will be redirected.
Internal IP address	ip; default: none	The IP address to which the incoming connection will be redirected.
Internal port	integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none	The port number to which the incoming connection will be redirected.
Enable NAT loopback	off | on ; default: on	NAT loopback a.k.a. NAT reflection a.k.a. NAT hairpinning is a method of accessing an internal server using a public IP. NAT loopback enables your local network (i.e., behind your NAT device) to connect to a forward-facing IP address of a machine that it also on your local network.
Extra arguments	string; default: none	Adds extra iptables options to the rule.

Traffic rules

The Traffic rules tab is used to set firewall rules that filter traffic moving through the device. The figure below is an example of the Traffic rules table:

Traffic rules configuration

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In order to begin editing a traffic rule, click the button that looks like a pencil next to it:

You will be redirected to that rule's configuration page:

Field	Value	Description
Enable	off | on; Default on	Turns the rule on or off.
Name	string; Default none	Name of the rule. This is used for easier management purposes.
Restrict to address family	IPv4 and IPv6 | IPv4 only | IPv6 only; Default: IPv4 and IPv6	IP address family to which the rule will apply to.
Protocol	TCP+UDP | TCP | UDP | ICMP | -- custom --; Default: TCP+UDP	Specifies to which protocols the rule should apply.
Source zone	firewall zone name; default: wan	The zone to which the third party will be connecting.
Source MAC address	mac; default: none	MAC address(es) of connecting hosts. The rule will apply only to hosts that match MAC addresses specified in this field. Leave empty to make the rule skip MAC address matching.
Source address	ip | ip/netmask; default: any	IP address or network segment used by connecting hosts. The rule will apply only to hosts that connect from IP addresses specified in this field. To specify a network segment instead of one IP address, add a forward slash followed by the netmask length after the network indication (for example, 10.0.0.0/8).
Source port	integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none	Port number(s) used by the connecting host. The rule will match the source port used by the connecting host with the port number(s) specified in this field. Leave empty to make the rule skip source port matching.
Destination zone	firewall zone; Default: Device (input)	Target zone of the incoming connection.
Destination address	ip | ip/netmask; Default: any	Tagert IP address or network segment of the incoming connection.
Destination port	integer [0..65535] | range of integers [0..65534] - [1..65535]; Default: none	Tagert port or range of ports of the incoming connection.
Action	DROP | ACCEPT | REJECT; Default: ACCEPT	Action that is to be taken when a packet meets the MATCH conditions. ACCEPT – packet gets to continue to the next chain. DROP – packet is stopped and deleted. REJECT – packet is stopped, deleted and, differently from Drop, an ICMP packet containing a message of rejection is sent to the source from which the dropped packet came.
Extra arguments	string; Default: none	Adds extra .iptables options to the rule.
Week days	days of the week [Sunday..Saturday]; Default: none	Specifies on which days of the week the rule is valid.
Month days	days of the month [1..31]; Default: none	Specifies on which days of the month the rule is valid.
Start Time (hh:mm:ss)	time [0..23:0..59:0..59]; Default: none	Indicates the beginning of the time period during which the rule is valid.
Stop Time (hh:mm:ss)	time [0..23:0..59:0..59]; Default: none	Indicates the end of the time period during which the rule is valid.
Start Date (yyyy-mm-dd)	date [0000..9999:1..12:1..31]; Default: none	Indicates the first day of the date of the period during which the rule is valid.
Stop Date (yyyy-mm-dd)	date [0000..9999:1..12:1..31]; Default: none	Indicates the last day of the date of the period during which the rule is valid.
Time in UTC	yes | no; Default: no	Specifies whether the device should use UTC time. If this is disabled, the time zone specified in the [[{{{name}}} NTP|NTP]] section will be used.

Open ports on device

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The Open ports on device section provides a quick way to set simple rules that allow traffic on specified ports of the device. The figure below is an example of the Open ports on device section and the table below provides information on the fields contained in that section:

[[File:{{{file_open_ports_on_device}}}]]

Field	Value	Description
Name	string; Default: none	The name of the rule. This is used for easier management purposes. The name field is filled automatically when port numbers are specified, unless the name was specified beforehand by the user.
Protocol	TCP+UDP | TCP | UDP | Other; Default: TCP+UDP	Specifies to which protocols the rule should apply.
External port	integer [0..65535] | range of integers [0..65534] - [1..65535]; Default: none	Specifies which port(s) should be opened.

New forward rule

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The New forward rule section is used to create firewall rules that control traffic on the FORWARD chain. The figure below is an example of the New forward rule section and the table below provides information on the fields contained in that section:

Field	Value	Description
Name	string; Default: none	The name of the rule. This is used for easier management purposes.
Source zone	firewall zone; Default: WAN	The zone from which traffic has originated.
Destination zone	firewall zone; Default: LAN	The zone to which traffic will be forwarded to.
Add	- (interactive button)	Creates the rule and redirects you to the rule's configuration page

Source NAT

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Source NAT is a specific form of masquerading which allows fine grained control over the source IP used for outgoing traffic. For example, to map multiple WAN addresses to internal subnets.

New source NAT

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The New Source NAT section is used to add custom source NAT rules. The figure below is an example of the New source NAT section and the table below provides information on the fields contained in that section:

Field	Value	Description
Name	string; Default: none	The name of the rule. This is used for easier management purposes.
Source zone	firewall zone; Default: LAN	The zone from which traffic has originated.
Destination zone	firewall zone; Default: WAN	The zone to which traffic will be forwarded to.
To source IP	ip | do not rewrite; Default: Do not rewrite	Changes the source IP in the packet header to the value specified in this field.
To source port	integer [0..65335] | do not rewrite; Default: Do not rewrite	Changes the source port in the packet header to the value specified in this field.
Add	- (interactive button)	Creates the rule and redirects you to the rule's configuration page.

Custom rules

The Custom rules tab provides you with the possibility to execute iptables commands which are not otherwise covered by the device's firewall framework. The commands are executed after each firewall restart, right after the default rule set has been loaded.

The figure below is an example of the Custom rules tab:

The rules added here are saved in the /etc/firewall.user file. Feel free to edit that file instead for the same effect in case you don't have access to the device's WebUI.

The Save button restarts the firewall service. Thus, adding the custom rules specified in this section to the device's list of firewall rules.

The Reset button resets the custom rules field to its default state.

NAT helpers

The NAT Helpers section provides you with the possibility to add firewall exceptions for some VoIP protocols, namely SIP and H.323. In other words, these functions provide a pass-through for VoIP communications between the device's LAN and WAN.

Technical explanation:

FTP, SIP and H.323 protocols are harder to filter by firewalls since they violate layering by introducing OSI layer 3/4 parameters in the OSI layer 7. NAT helpers are modules that are able to assist the firewall in tracking these protocols. These helpers create the so-called expectations that can be used to open necessary ports for RELATED connections. For example, FTP, GRE and PPTP helpers are enabled by default.

Field	Value	Description
H323	off | on; Default: off	Turns H323 filtering on or off.
SIP	off | on; Default: off	Turns SIP filtering on or off.

overview [[Category:{{{name}}} Network section]]