RUTX12 Firewall

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Main Page > RUTX Routers > RUTX12 > RUTX12 Manual > RUTX12 WebUI > RUTX12 Network section > RUTX12 Firewall

The information in this page is updated in accordance with firmware version RUTX_R_00.07.06.6.


Summary

RUTX12 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 page for RUTX12 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.

Networking rutos manual webui basic advanced mode 75.gif

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:

Networking rutos manual firewall general settings general settings v3.png

Field Value Description
Drop invalid packets off | on; default: off If enabled, a "Drop" action will be performed on packets that are determined to be invalid.
Automatic helper assignment off | on; default: on Automatically assigns conntrack helpers based on traffic protocol and port. If turned off, conntrack helpers can be selected for each zone.
Input Reject | Drop | Accept; default: Reject 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.

Routing/NAT Offloading


The Routing/NAT Offloading is used to turns software flow offloading on or off.

The device checks whether the flow (sequence of related packets) is of a received a packed is known. Packets of unknown flow are forwarded to the networking stack. Meanwhile, if the flow is known, NAT is applied (if matched) and the packet is forwarded to the correct destination port. This process is called software flow offloading. Hardware flow offloading is used to execute functions of the router using the hardware directly, instead of a process of software functions.

Networking rutos manual firewall general settings routing nat offloading rutx v2.png

Field Value Description
Software flow offloading off | on; default: on Turns software flow offloading on or off.
Hardware flow offloading off | on; default: on Turns hardware flow offloading on or off.

Zones


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 v2.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 edit button Networking rutx trb14x manual edit button v2.png next to a zone:

Networking rutos manual firewall general settings zones edit button v2.png

Zones: General Settings


Networking rutos manual firewall general settings zones general settings v2.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


Networking rutos manual firewall general settings zones advanced settings v4.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.
Conntrack helpers Amanda backup and archiving proto (AMANDA) | FTP passive connection tracking (FTP) | RAS proto tracking (RAS) | Q.931 proto tracking (Q.931) | IRC DCC connection tracking (IRC) | NetBIOS name service broadcast tracking (NETBIOS-NS) | PPTP VPN connection tracking (PPTP) | SIP VoIP connection tracking (SIP) | SNMP monitoring connection tracking (SNMP) | TFTP connection tracking (TFTP); default: none This option appears only when automatic helper assignment option in the firewall's general settings is disabled. Explicitly choses allowed connection tracking helpers for zone traffic.

Zones: Inter-zone Forwarding


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 v1.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

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 v2.png

Add New Port Forward


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 v3.png

Field Value Description
Name string; default: none Name of the rule. This is used for easier management purposes.
External port integer [0..65535] | range of integers [0..65534] - [1..65535] | port inversion [!0..!65535]; default: none The port number to which hosts will be connecting.
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] | port inversion [!0..!65535]; default: none The port number to which the incoming connection will be redirected.

Port Forwards Configuration


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 edit button Networking rutx trb14x manual edit button v2.png next to it:

Networking rutos manual firewall port forwards edit button v3.png

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

Networking rutos manual firewall port forwards configuration v3.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 | ICMP | All | +Add new; 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.)
External port integer [0..65535] | range of integers [0..65534] - [1..65535] | port inversion [!0..!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 Device LAN IP; default: Device LAN IP The IP address to which the incoming connection will be redirected.
Internal port integer [0..65535] | range of integers [0..65534] - [1..65535] | port inversion [!0..!65535]; default: none The port number to which the incoming connection will be redirected.

Advanced settings:

Networking rutos manual firewall port forwards configuration advanced v2.png

Field Value Description
Source MAC address mac; default: none MAC address 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] | port inversion [!0..!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).
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:

Networking rutos manual firewall traffic rules v2.png

Traffic Rule Configuration


In order to begin editing a traffic rule, click the edit button Networking rutx trb14x manual edit button v2.png next to it:

Networking rutos manual firewall traffic rules edit button v2.png

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

General settings


Networking rutos manual firewall traffic rules configuration general settings v2.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 | All | +Add new |ICMP; default: depends on the rule Specifies to which protocols the rule should apply.
Match ICMP type Any | ICMP-type | + Add new; default: none Allows matching specific ICMP types.
Source zone firewall zone name; default: wan The zone to which the third party will be connecting.
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] | port inversion [!0..!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. Port negation using is also available, for ex. !1.
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] | port inversion [!0..!65535]; default: none Tagert port or range of ports of the incoming connection. Port negation using is also available, for ex. !1.
Action Drop | Accept | Reject | Don't track | DSCP | Mark; 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.
  • DSCP – packet is marked with specified DiffServ Code Point value.
  • Mark – packet is marked with specified firewall mark..

Advanced settings


Networking rutos manual firewall traffic rules configuration advanced settings v2.png

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.
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.
DSCP: Set Target value Default | DSCP values; default: Default If specified, target traffic against the given firewall DSCP value.
Mark: Set Target value hex; default: none If specified, target traffic against the given firewall mark, e.g. FF or ff to target mark 255.
Match DSCP | Mark; default: none Match traffic against the given DSCP value or firewall mark
DSCP: Set Match value Default | DSCP values; default: Default Match traffic against the given firewall DSCP value.
Mark: Set Match value hex; default: none If specified, match traffic against the given firewall mark, e.g. FF or ff to match mark 255.
Extra arguments string; default: none Adds extra .iptables options to the rule.

Time restrictions


Networking rutos manual firewall traffic rules configuration time restrictions v2.png

Week days days of the week [Monday..Sunday]; 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 System → Administration → NTP page will be used.

Open Ports on Router


In the Add new instance section, select Open ports on router. This 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 v2.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 | ICMP | All | +Add new; default: none Specifies to which protocols the rule should apply.
External port integer [0..65535] | range of integers [0..65534] - [1..65535] | port inversion [!0..!65535]; default: none Specifies which port(s) should be opened.

Add New Forward Rule


In the Add new instance section, select Add new forward rule. This 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 v2.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

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

Source NAT


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 v2.png

Add New Source NAT


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

Networking rutos manual firewall nat rules add new source nat v2.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] | port inversion [!0..!65535] | 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


In order to begin editing a traffic rule, click the edit button Networking rutx trb14x manual edit button v2.png next to it:

Networking rutos manual firewall nat rules source nat edit button v2.png

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

Networking rutos manual firewall nat rules configuration mobile general.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 | ICMP | +Add new; 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] | port inversion [!0..!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] | port inversion [!0..!65535]; default: none Matches traffic destined for the specified port number.
Rewrite port integer [0..65535] | range of integers [0..65534] - [1..65535] | port inversion [!0..!65535]; default: No rewrite Rewrite matched traffic to the given source port.
   Networking rutos manual firewall nat rules configuration mobile advanced.png
   
Field Value Description
Extra arguments string; default: none Adds extra .iptables options to the rule.
   Networking rutos manual firewall nat rules configuration mobile time restriction.png
   
Field Value Description
Week days days of the week [Monday..Sunday]; 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 System → Administration → NTP page will be used.

Attack Prevention

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

SYN Flood Protection


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 v2.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 flooded
SYN flood burst integer; default: 10 Sets burst limit for SYN packets above which the traffic is considered flooded if it exceeds the allowed rate
TCP SYN cookies off | on; default: on Enables the use of SYN cookies (particular choices of initial TCP sequence numbers by TCP servers)

Remote ICMP Requests


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 v2.png

Field Value Description
Enable ICMP requests off | on; default: on Turns the rule on or off.
Enable ICMP limit off | on; default: off 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


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

Networking rutos manual firewall attack prevention ssh attack prevention v2.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 [1..10000]; default: none Maximum SSH connections during the set period
Limit burst integer [1..10000]; default: none Indicates the maximum burst before the above limit kicks in.

HTTP Attack Prevention


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 v2.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 [1..10000]; default: none Maximum HTTP connections during the set period.
Limit burst integer [1..10000]; default: none Indicates the maximum burst before the above limit kicks in.

HTTPS Attack Prevention


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 v2.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 [1..10000]; default: none Maximum HTTPS connections during the set period.
Limit burst integer [1..10000]; default: none Indicates the maximum burst number before the above limit kicks in.

Port Scan


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 v2.png

Field Value Description
Enable off | on; default: off Turns the function on or off.
Scan count integer [5..10000]; default: none How many port scans before blocked.
Interval integer [10..4096]; default: none 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.

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.

Note: Custom rules are not recommended to be used with hostnames. The rules will not remain active after reboot due to security reasons.

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.

DMZ

The DMZ is a security concept. It comprises the separation of the LAN-side network into at least two networks: the user LAN and the DMZ. Generally the DMZ is imprisoned: only access to certain ports from the Internet are allowed into the DMZ, while the DMZ is not allowed to establish new connections to the WAN-side or LAN-side networks. That way, if a server inside of the DMZ is hacked the potential damage that can be done remains restricted! The whole point of the DMZ is to cleanly create a unique firewall rule set that dramatically restricts access in to, and out of the, DMZ.

Networking rutos manual network firewall dmz v2.png

Field Value Description
Enable off | on; default: off Enables the DMZ configuration.
Host IP ipv4; default: none Specifies the IP address of the DMZ host.
Protocol All | TCP | UDP | ICMP; default: None Specifies for which protocols the DMZ will be used.
Ports 0..65535 | port range | port negation; default: none Match incoming traffic directed at the given destination port or port range on DMZ host IP.