RUTX11 Firewall

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Main Page > RUTX Routers > RUTX11 > RUTX11 Manual > RUTX11 WebUI > RUTX11 Network section > RUTX11 Firewall

The information in this page is updated in accordance with firmware version RUTX_R_00.02.05.1.

Summary[edit | edit source]

RUTX11 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 of the user manual provides an overview of the Firewall section for RUTX11 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 "Basic" button under "Mode", which is located at the top-right corner of the WebUI.

Networking rutx manual webui basic advanced mode.gif

General settings[edit | edit source]

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:

Networking rutos manual firewall general settings general settings.png

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[edit | edit source]


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:

Networking rutos manual firewall general settings zones.png


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 Networking rutx trb14x manual edit button v1.png next to a zone:

Networking rutos manual firewall general settings zones edit button.png

Zones: General Settings[edit | edit source]


Networking rutos manual firewall general settings zones general settings.png

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 network interface(s); default: none Network or networks that belong to the zone.

Zones: Advanced Settings[edit | edit source]


Networking rutos manual firewall general settings zones advanced settings.png

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[edit | edit source]


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

Networking rutos manual firewall general settings zones inter-zone forwarding mobile 1 dualsim 1 wired 1.png

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[edit | edit source]

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

Networking rutx manual firewall port forwards scheme v1.png


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

Networking rutos manual firewall port forwards port forwards.png

Add New Port Forward[edit | edit source]


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

Networking rutos manual firewall port forwards add new port forward.png

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[edit | edit source]


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 Networking rutx trb14x manual edit button v1.png next to it:

Networking rutos manual firewall port forwards edit button.png

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

Networking rutos manual firewall port forwards configuration mobile 1 dualsim 1 wired 1.png

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[edit | edit source]

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:

Networking rutos manual firewall traffic rules.png

Traffic Rule Configuration[edit | edit source]


In order to begin editing a traffic rule, click the button that looks like a pencil Networking rutx trb14x manual edit button v1.png next to it:

Networking rutos manual firewall traffic rules edit button.png

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

Networking rutos manual firewall traffic rules configuration mobile 1 dualsim 1 wired 1.png

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 | Don't track; default: Accept Action that is to be taken when a packet matches the conditions of the rule.
  • Drop – packet is stopped and deleted.
  • Accept – packet gets to continue to the next chain.
  • 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.
  • Don't track – packet is no longer tracked as it moves forward.
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 off | on; default: no Specifies whether the device should use UTC time. If this is disabled, the time zone specified in the Services → NTP page will be used.

Open Ports on Router[edit | edit source]


The Open Ports on Router 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:

Networking rutos manual firewall traffic rules open ports on router.png

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.

Add New Forward Rule[edit | edit source]


The Add 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 Add New Forward Rule section and the table below provides information on the fields contained in that section:

Networking rutos manual firewall traffic rules add new forward rule.png

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

NAT Rules[edit | edit source]

Network address translation (NAT) is method of modifying the source/destination address and/or port information in a packet's IP header.

Source NAT[edit | edit source]


Source NAT (SNAT) is a form of masquerading used to change a packet's source address and/or port number to a static, user-defined value. SNAT is performed in the POSTROUTING chain, just before a packet leaves the device.

The Source NAT section displays currently existing SNAT rules.

Networking rutos manual firewall nat rules source nat.png

Add New Source NAT[edit | edit source]


The Add New Source NAT section is used to create new source NAT rules.

Networking rutos manual firewall nat rules add new source nat.png

Field Value Description
Name string; default: none The name of the rule. Used only for easier management purposes.
Source zone firewall zone; default: lan Matches traffic originated from the specified zone.
Destination Zone firewall zone; default: wan Matches traffic destined for the specified zone.
To source IP ip | do not rewrite; default: none Changes the source IP address in the packet header to the value specified in this field.
To Source Port integer [0..65335] | do not rewrite; default: none Changes the source port in the packet header to the value specified in this field.
Add - (interactive button) Creates the rule in accordance with the given parameter and redirects you to the rule's configuration page.

Source NAT Configuration[edit | edit source]


In order to begin editing a traffic rule, click the button that looks like a pencil Networking rutx trb14x manual edit button v1.png next to it:

Networking rutos manual firewall nat rules source nat edit button.png

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

Networking rutos manual firewall nat rules configuration mobile 1 dualsim 1 wired 1.png

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 All protocols | TCP+UDP | TCP | UDP | ICMP | -- custom --; default: All protocols Specifies to which protocols the rule should apply.
Source zone firewall zone; default: lan Matches traffic originated from the specified zone.
Source IP address ip | ip/netmask; default: Any Mathes traffic originated from specified IP address or network segment.
Source port integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none Mathes traffic originated from specified port number.
Destination zone firewall zone; default: wan Matches traffic destined for the specified zone.
Destination IP address ip | ip/netmask; default: any Matches traffic destined for the specified IP address or network segment.
Destination port integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none Matches traffic destined for the specified port number.
SNAT address ip; default: none Changes matched traffic packet source IP address to the value specified in this field.
SNAT port integer [0..65535] | range of integers [0..65534] - [1..65535]; default: none Changes matched traffic packet source port number to the value specified in this field.
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 off | on; default: no Specifies whether the device should use UTC time. If this is disabled, the time zone specified in the Services → NTP page will be used.

Custom rules[edit | edit source]

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:

Networking rutos manual firewall custom rules.png

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.

Attack Prevention[edit | edit source]

The Attack Prevention menu tab provides the possibility to configure protections against certain types of online attacks.

SYN Flood Protection[edit | edit source]


SYN Flood Protection allows you to protect yourself from attacks that exploit part of the normal TCP three-way handshake to consume resources on the targeted server and render it unresponsive. Essentially, with SYN flood DDOS, the offender sends TCP connection requests faster than the targeted machine can process them, causing network over-saturation.

Networking rutos manual firewall attack prevention syn flood protection.png

Field Value Description
Enable SYN flood protection off | on; default: on Turns the rule on or off.
SYN flood rate integer; default: 5 Set rate limit (packets per second) for SYN packets above which the traffic is considered floodedb
SYN flood burst integer; default: 10 Sets burst limit for SYN packets above which the traffic is considered flooded if it exceeds the allowed ratbe
TCP SYN cookies off | on; default: off Enables the use of SYN cookies (particular choices of initial TCP sequence numbers by TCP servers)b

Remote ICMP Requests[edit | edit source]


Some attackers use ICMP echo request packets directed to IP broadcast addresses from remote locations to generate denial-of-service attacks. You can set up some custom restrictions to help protect your router from ICMP bursts.

Networking rutos manual firewall attack prevention remote icmp requests.png

Field Value Description
Enable ICMP requests off | on; default: on Turns the rule on or off.
Enable ICMP limit off | on; default: no Turns ICMP echo-request limit in selected period on or off.
Limit period Second | Minute | Hour | Day; default: Second Period length for matching the conditions of the rule.
Limit integer; default: 5 Maximum ICMP echo-request number during the period.
Limit burst integer; default: 10 Indicates the maximum burst before the above limit kicks in.

SSH Attack Prevention[edit | edit source]


This protection prevent SSH attacks by limiting connections in a defined period.

Networking rutos manual firewall attack prevention ssh attack prevention.png

Field Value Description
Enable SSH limit off | on; default: off Turns the rule on or off.
Limit period Second | Minute | Hour | Day; default: Second Period length for matching the conditions of the rule.
Limit integer; default: 5 Maximum SSH connections during the set period
Limit burst integer; default: 10 Indicates the maximum burst before the above limit kicks in.

HTTP Attack Prevention[edit | edit source]


An HTTP attack sends a complete, legitimate HTTP header, which includes a 'Content-Length' field to specify the size of the message body to follow. However, the attacker then proceeds to send the actual message body at an extremely slow rate (e.g. 1 byte/100 seconds.) Due to the entire message being correct and complete, the target server will attempt to obey the 'Content-Length' field in the header, and wait for the entire body of the message to be transmitted, hence slowing it down.

Networking rutos manual firewall attack prevention http attack prevention.png

Field Value Description
Enable HTTP limit off | on; default: off Turns the rule on or off.
Limit period Second | Minute | Hour | Day; default: Second Period length for matching the conditions of the rule.
Limit integer; default: 5 Maximum HTTP connections during the set period<./td>
Limit burst integer; default: 10 Indicates the maximum burst before the above limit kicks in.

HTTPS Attack Prevention[edit | edit source]


This section allows you to enable protection against HTTPS attacks, also known as "man-in-the-middle" attacks (MITM).

In cryptography and computer security, a man-in-the-middle attack (MITM) is an attack where the perpetrator secretly relays and possibly alters the communication between two parties who believe they are directly communicating with each other. One example of man-in-the-middle attacks is active eavesdropping, in which the attacker makes independent connections with the victims and relays messages between them to make them believe they are talking directly to each other over a private connection, when in fact the entire conversation is controlled by the attacker.

Networking rutos manual firewall attack prevention https attack prevention.png

Field Value Description
Enable HTTPS limit off | on; default: off Turns the rule on or off.
Limit period Second | Minute | Hour | Day; default: Second Period length for matching the conditions of the rule.
Limit integer; default: 5 Maximum HTTPS connections during the set period.
Limit burst integer; default: 10 Indicates the maximum burst number before the above limit kicks in.

Port Scan[edit | edit source]


Port Scan attacks scan which of the targeted host's ports are open. Network ports are the entry points to a machine that is connected to the Internet. A service that listens on a port is able to receive data from a client application, process it and send a response back. Malicious clients can sometimes exploit vulnerabilities in the server code so they gain access to sensitive data or execute malicious code on the machine remotely. Port scanning is usually done in the initial phase of a penetration test in order to discover all network entry points into the target system. The Port Scan section provides you with the possibility to enable protection against port scanning software. The Defending Type section provides the possibility for the user to enable protections from certain types of online attacks. These include SYN-FIN, SYN-RST, X-Mas, FIN scan and NULLflags attacks.

Networking rutos manual firewall attack prevention port scan.png

Field Value Description
Enable off | on; default: off Turns the function on or off.
Scan count integer [5..65534]; default: 5 How many port scans before blocked.
Interval integer [10..60]; default: 10 Time interval in seconds in which port scans are counted.
SYN-FIN attack off | on; default: off Turns protection from SYN-FIN attacks on or off.
SYN-RST attack off | on; default: off Turns protection from SYN-RST attacks on or off.
X-Mas attack off | on; default: off Turns protection from X-Mas attacks on or off.
FIN scan off | on; default: off Turns protection from FIN scan attacks on or off.
NULLflags attack off | on; default: off Turns protection from NULLflags attacks on or off.

Helpers

The 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.

Networking rutos manual firewall helpers nat helpers.png

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.