In this page you find:
The Panda GateDefender Appliance includes many useful services to prevent threats and to monitor the networks and the running daemons, whose activation and set up is explained in this section. In particular, among them, we highlight the various proxy services, such as the antivirus engine, as well as the intrusion detection system, high availability, and traffic monitoring. The available services appear as items in the sub-menu list on the left-hand side of the screen.
The DHCP server is used by the clients (workstations and servers) in the zones controlled by the Panda GateDefender Appliance to receive an IP address (“lease”), and allows to control the IP address assigned to them in a centralised way. Two types of leases can be assigned to clients: Dynamic and fixed. The DHCP server page is divided into two or three boxes, namely DHCP, in which to configure the DHCP server, Current fixed leases, showing the fixed leases, and Current dynamic leases that shows up only if at least one client has obtained a dynamic lease. Dynamic leases are assigned on a network basis within a given range that is configured in the first box, whereas fixed leases are assigned on a per-host basis and are configured in the second box.
When a client (be it either a host or another device such as networked printer) joins the network it will automatically get a valid IP address from a range of addresses and other settings from the DHCP service. The client must be configured to use DHCP, which is sometimes called “automatic network configuration”, and is often the default setting on most workstations. Dynamic leases are configured on a zone basis: for example, it is possible to enable them only for clients in the GREEN zone, while the other active zones receive only fixed leases.
It is however possible to let also devices in the ORANGE (DMZ) or BLUE (WLAN) zone to receive dynamic leases.
Note
If the BLUE zone is enabled but managed by the hotspot, the message DHCP configuration is managed by hotspot appears, preventing to configure it here.
To customise the DHCP parameter for each zone, click on the small icon
next to the Settings label. These are the available
options:
The range of IP addresses to be supplied to the clients. These addresses have to be within the subnet that has been assigned to the corresponding zone. If some hosts should receive a fixed lease, (see below), make sure their IP addresses are included neither in this range nor in the range of the OpenVPN address pool (see Menubar ‣ VPN ‣ OpenVPN server) to avoid conflicts.
Leaving these two fields blank will use the whole IP range of the zone for dynamic leases.
Advanced users might want to add some custom configuration lines to be added to the dhcpd.conf file (e.g., custom routes to subnets) by writing them in the text area at the bottom, marked with the Custom configuration lines label.
Warning
No syntax check on these lines is carried out: the lines are appended to the configuration file. Any mistake here might inhibit the DHCP server from starting!
It is sometimes necessary or desirable for certain devices to always use the same IP address while still using DHCP, for example servers that provide services like a VoIP box, a SVN repository, a file server, or devices like printers or scanners. A fixed lease is usually referred to as Static IP Address, since a device will always receive the same IP address when requesting a lease from the DHCP server.
This box reports the list of all the fixed leases currently active in the local network, providing several information about that lease. By clicking on the Add a fixed lease link, new fixed leases can be assigned to a device and insert all the information that will be displayed in the list. The devices are identified by their MAC addresses.
Note
Assigning a fixed lease from the DHCP server is very different from setting up the IP address manually on a device. Indeed, in the latter case, the device will still contact the DHCP server to receive its address and to announce its presence on the network. When the IP address required by the device has already been assigned, however, a dynamic lease will be given to the device.
The following parameters can be set for fixed leases:
The actions available for each fixed lease in the table are:
- toggle the status of the lease, enabled or disabled.
- modify the property of the lease.
- remove the lease.A use case for a fixed lease.
A use case that shows the usefulness of a fixed lease is the case of thin clients or disk-less workstations on the network that use PXE, i.e., boot the operating system from an image supplied by a networked tftp server. If the tftp server is hosted on the same server with the DHCP, the thin client receives both the lease and the image from the same server. More often, however, the tftp server is hosted on another server on the network, hence the client must be redirected to this server by the DHCP server, an operation that can be done easily adding a fixed lease on the DHCP server for the thin client, adding a next-address and the filename of the image to boot.
Besides the information supplied during the fixed lease creation, the list allow each lease to be enabled or disabled (by ticking the checkbox), edited, or deleted, by clicking on the icons in the Actions column. Editing a lease will open the same form as the creation of a new lease, whereas deleting a lease will immediately remove it from the configuration.
Note
All leases assigned by the DHCP server are stored by default in the /var/lib/dhcp/dhcpd.leases file. Although the DHCP daemon takes care of cleaning that file, it may happen that the file stores lease that have already been expired and are quite old. This is not a problem and does not interfere with the normal DHCP server working. A typical entry in that file is:
lease 192.168.58.157 {
starts 2 2013/06/11 13:00:21;
ends 5 2013/06/14 01:00:21;
binding state active;
next binding state free;
hardware ethernet 00:14:22:b1:09:9b;
}
When the DHCP server is active, and at least one client has received a (dynamic) IP address, a third box appears at the bottom of the page, containing the list of the currently assigned dynamic IP addresses. This list report the IP address, the MAC address, the hostname, and the expiry time of the lease associated to each client.
A DNS server provides a service that allows to resolve the (numeric) IP address of a host, given its hostname, and vice versa, and works perfectly for hosts with fixed IP address and hostname.
DDNS providers, like DynDNS or no-IP, offer a similar service when the IP addresses is dynamic, which is normally the case when using residential ADSL connections: Any domain name can be registered and associated to a server with a dynamic IP address, which communicates any IP address change to the DDNS provider. To be compatible and to integrate with the root DNS servers, each time IP address changes, the update must then be actively propagated from the DDNS provider.
The Panda GateDefender Appliance includes a dynamic DNS client for 14 different providers and if enabled, it will automatically connect to the dynamic DNS provider to communicate the new IP address whenever it changes.
Note
If no dynamic DNS account has been set up, detailed instruction to register a new one, detailed online helps and howtos are available on the web site of the providers.
This page displays the list of the Dynamic DNS accounts. Indeed, more than one DDNS provider can be used. For each account, the list shows information about the service used, the hostname and domain name registered, if the anonymous proxy and the wildcards are active, if it is enabled, and the possible actions:
- toggle the status of the lease, enabled or disabled. - modify the property of the lease. - remove the lease.New accounts can be created by clicking on the Add a host link, providing the following parameters:
Note
It is still necessary to export a service to the RED zone to be able to use the domain name to connect to the Panda GateDefender Appliance from the Internet using its dynamic IP address, since the dynamic DNS provider only resolves the domain name and not the associated services. Exporting a service might typically involve setting up port forwarding (see Menubar ‣ Firewall ‣ Port forwarding / NAT).
After making a change in the configuration or to immediately update the dynamic DNS for all the defined accounts, click on the Force update button. This proves useful for example when the uplink has been disconnected and the REDIP has changed: When this happens, updating all the DDNS accounts is required, otherwise the services offered via DDNS will be unreachable.
The antivirus engine on Panda GateDefender Appliance is Panda, which will be used for the research of viruses and malware within files and documents that pass through the Panda GateDefender Appliance via one of the running proxy services. There is only one tab in this page: Panda Antivirus.
Archive bomb and DoS.
Archive bombs are archives that use a number of tricks to overload an antivirus software to the point that they hog most of the resources of the computer hosting it, an action called DoS attack. These tricks include: Small archives made of large files with repeated content that compress well (for example, a file of 1 GB containing only zeros compresses down to just 1 MB using zip); multiple nested archives (i.e., zip files inside zip files); archives that contain a large number of empty files, and so forth. Decompressing archive files with any of those characteristic poses a serious challenge to the normal activities of a server or a workstation, since a lot of resources are needed (especially RAM and CPU) and taken away from users’ availability.
The Panda GateDefender Appliance features the Panda Antivirus Engine to protect internal networks against viruses and malware.
The first option available is to select the update cycle of the anti-virus signatures, which can be: hourly, daily, weekly, or monthly.
The scan options to be configured are grouped in 3 sections:
The following option relate to the search for and the scan of various types of malware programs that may infect the workstations and server which lay behind the Panda GateDefender Appliance.
These options concern the behaviour of the anti-virus when dealing with compressed files. More information about here.
The Panda GateDefender Appliance uses NTP to keep its system time synchronised with time servers on the Internet. The settings available are grouped into two boxes.
A number of time server hosts on the Internet are preconfigured and used by the system, but custom time servers can be specified after ticking the Override default NTP servers checkbox. This might prove necessary when running a setup that does not allow the Panda GateDefender Appliance to reach the Internet. Several time servers addresses can be supplied, one per line, in the small form that will show up.
This box also shows the current time zone setting, that can also be changed by choosing a different one from the drop-down menu. An immediate synchronisation can be done by clicking on the Synchronize now button.
The second box gives the possibility to manually change the system time. While this is not recommended, this action proves useful when the system clock is way off and an immediate update of the Panda GateDefender Appliance‘s clock to the correct time is needed.
Automatic synchronisation using time servers is not done instantly, but the clock is “slow down” or “speed up” a bit to recover and align to the correct time, hence a system with a significant error in its time may require a long period to be corrected. In those cases, forcing a manual synchronisation represents a more drastic but immediate solution.
The mail quarantine is a special place on the Panda GateDefender Appliance hard disk where all the e-mails that the SMTP proxy recognises as containing spam, malware, viruses, or with suspicious attachments are stored instead of being delivered. Here, those e-mails can be safely analysed and actions can be taken to manage them. To activate the mail quarantine, go to Menubar ‣ Proxy ‣ SMTP ‣ Configuration and in the SPAM settings, Virus Settings, and File settings boxes, choose the option move to default quarantine location from the drop down menus.
The space dedicated to the mail quarantine depends on several factors, like e.g., the type of appliance, the size of the quarantined e-mails, or even what other services are active on the appliance, hence it is not possible to give precise numbers. In case the quarantine storage is filled up before the Quarantine retention time has been reached (see Quarantine settings in the SMTP Proxy module), it is necessary to manually delete quarantined e-mails to make room for new e-mails.
The Mail quarantine is organised in two tabs: Quarantine and Summary Reports. The former contains a list of the e-mail stored in the quarantine and allows to browse and manage them, while the latter allows to generate periodical reports about the quarantine’s content and manage their dispatch.
The mail quarantine page contains a table with the list of all mail moved to the quarantine, above which there is a navigation bar to browse the e-mails.
The table contains the following information about the mail saved in the quarantine.
View the message, 
download the
message, 
release the message and delivery it to the
original recipient, and 
deletes the email. See below for
more details.Underneath the table, two buttons allow to carry out actions when more than one message is selected in the table.
When clicking on the view message icon, the list of emails is replaced with a 3-boxed page, showing various details about the selected e-mail.
This box presents a more detailed view of the e-mail’s data reported in the e-mail list: The reason why the e-mail ended in the quarantine, the sender and recipients, along with carbon copy (CC) addressee, subject, date and time of receiving, and e-mail’s size.
The full, original header of the e-mail, which can give useful information, among which for example the path followed by the e-mail.
If the email has one or more attachments, they are shown here along with their details. Moreover, every HTML attachment is shown with its full source code.
At the bottom, there is an option available:
Periodical reports about quarantined e-mails can automatically be sent to inform the original recipient of the e-mail. In this page it is possible to activate and manage the frequency and settings of this service.
Note
This functionality requires that the SMTP Proxy be correctly set up and running, otherwise it would not send any reports.
Alternatives to notify recipients of quarantined e-mails.
There are two approaches to notify users that they received one or more e-mails that ended in the quarantine:
These two approaches are not exclusive: It is allowed to employ both of them.
Moreover, there is also the possibility to supply a list of sender addresses whose e-mail will never be part of any summary report.
Finally, wildcards and regular expressions can be used to avoid the necessity to write a long list of addresses.
Warning
Make sure to not misuse wildcards! In particular, writing a single asterisk * on a line will send an email notification to every user in every domain managed by the Panda GateDefender Appliance.
The summary reports service is not enable by default. To start it, click on the grey switch labelled Enable Summary Reports Emails. It will turn green and a number of configuration options appear.
By ticking the checkbox, the default address will appear as the sender of the report.
Note
The default e-mail address is the one specified during the network configuration, see
The report can be sent Daily, Weekly, or Monthly.
Note
If the value of option Quarantine retention time in Menubar ‣ Proxy ‣ SMTP ‣ Configuration ‣ Quarantine settings is lower than 30 (days), the Monthly option will not be available.
This form can be used to include a custom message in the report.
Hint
This form can be used to include in the report an e-mail address that the user can contact to ask for information or release the quarantined e-mail.
This multiselect box allows to choose which domains shall be monitored for dangerous e-mails and send them to the quarantine. When users in one of these domains receive a mail that ends in the quarantine, they will be notified with an email
Hint
To add a new domain to this box, add it in Menubar ‣ Proxy ‣ SMTP ‣ Incoming domains.
Warning
Make sure to not misuse wildcards! In particular, writing a single asterisk * on a line will send an email notification to every user in every domain managed by the Panda GateDefender Appliance !
See also
The Panda GateDefender Appliance includes SpamAssassin as the engine to find and fight spam e-mails. While it is successful in the vast majority of the cases, SpamAssassin needs to be trained to improve its abilities to intercept spam e-mails. The configuration of the training for the antispam engine can be done in this page: Indeed, SpamAssassin can learn automatically which e-mails are spam and which are not (the so called ham mails). To be able to learn, it needs to connect to an IMAP host and check the pre-defined folders for spam and ham messages.
The page for SpamAssassin consists of two boxes, one that contains a list of IMAP hosts used for learning, with the possibilities to manage them at various levels, and another one to modify the scheduling of the updates.
The first box allows the configuration of the training sources, by means of two links that, after clicking, will reveal two panels in which to specify the various configuration values. The default configuration, which is initially empty, is not used for training, but only provides values that are later inherited by the real training sources which can be added right below. By clicking on the Edit default configuration link, these setting can be configured:
Additional spam training sources can be added in the panel that appears upon clicking on the Add IMAP spam training source link. The options for the additional training hosts are the same as the default configuration options, except for the scheduling, which is always inherited from the default configuration, and for three new available options.
The other options can be defined just like in the default configuration and, when specified, they override the default values. To save the configuration of a source it is necessary to click on the Add Training Source button after all the desired values have been set. Several actions can be carried out on a training source:
- toggle the status of the IMAP host, enabled or disabled. - modify the property of the IMAP host. - remove the IMAP host.
- test the connection to the IMAP host.It can be enabled, disabled, edited, removed, or the connection tested by clicking on the appropriate icon.
Two additional actions are available and will be performed on all the connections, by clicking on one of the buttons located on the top right of the box.
Note
The antispam engine can be also trained in another way if the SMTP Proxy is enabled for incoming as well as for outgoing mails: This is done by sending spam mails to the special addresses spam@spam.spam and non-spam mails to ham@ham.ham. The hostnames spam.spam and ham.ham are added to the network configuration right after the network setup and are aliases for localhost. If these two addresses are not present, they can be added to the host configuration in Menubar ‣ Network ‣ Edit hosts ‣ Add a host on the Panda GateDefender Appliance.
In this box it is possible to schedule the automatic download of SpamAssassin signatures among the four options: Hourly, daily, weekly, and monthly.
The Panda GateDefender Appliance includes the well known intrusion detection (IDS) and prevention (IPS) system snort, which is directly built into iptables, to intercept and drop connections from unwanted or distrusted sources.
The page contains three tabs, Intrusion Prevention System, Rules, and Editor.
If snort is not active, a grey switch 
next to the Enable
Intrusion Prevention System label appears on the page and can be
clicked on to start the service. A message appears, informing that the
service is being restarted and after a short interval, the box will
contain some options to configure the service.
Ticking this box will let the Panda GateDefender Appliance automatically download the snort rules from the Panda Perimetral Management Console.
Note
If the Panda GateDefender Appliance is not registered, or its maintenance has expired, rules are not downloaded anymore. An informative message is also shown at the bottom of the page.
On the Rules tab appears the list of rule sets that are stored on the Panda GateDefender Appliance, along with the number of rules they contain and the actions that can be done on them:
- toggle the status of the rule set, enabled or disabled.
- The policy applied to packets, either they are
allowed to pass or not. - modify the property of the rule set. - remove the rule set.Note
When editing a ruleset in the Rules tab, the Editor page (see below) will open with that ruleset already selected.
All the actions, except for editing, can be carried out on more than one rulesets at once, by selecting them (tick the checkbox on the left of their filename) and pressing one of the button underneath the list.
By default, the policy for all the rulesets is set to alert. This behaviour can be changed by clicking on the alert icon to toggle the policy into block and the icon into a red shield. After clicking on the Apply button, that ruleset will not cause alerts anymore, but all the traffic that matches its rules will be blocked.
A ruleset can be deleted by clicking on the trash can icon, while a click on the pencil icon redirects to the Editor page in which to edit each rule independently.
At the top of the Editor page are shown the rulesets that can be edited. To chose more than one ruleset at once, hold the CTRL key and click on the rulesets.
After selecting and clicking on the Edit button, the list of the rules included in the selected ruleset(s) is shown. The list can be narrowed down by entering some terms in the text box next to the Search label. Like in the Rules page, the policy of every entry can be changed.
Warning
Turning on the IPS only implies that snort is running, but it does not yet filter the traffic. For snort to filter packets, the Allow with IPS Filter policy must be selected for the rules defined in the various Firewall configuration pages.
The Panda GateDefender Appliance can be run in an HA mode, that can easily be setup using at least two Panda GateDefender Appliances, one of which assumes the role of the active (i.e., master) firewall, while the remaining are standby (i.e., slave) firewalls.
If the master firewall fails, an election among the slaves takes place and one of them will become the new master, providing for transparent failover. If there is only one slave, though, it will immediately take over the master’s duties and allows a seamless failover transition to the secondary Panda GateDefender Appliance in the event of a hardware failure on the primary appliance. This provides unparalleled hardware availability and redundancy for critical network operations and security.
In order to start up the HA service, at least one master and one slave Panda GateDefender Appliances must be configured according to the following guidelines.
Note
The high availability module requires at least two completely identical Panda GateDefender Appliances.
An important point to focus on when deploying high availability is that a duplication method for each and every connection to the Panda appliance must be provided. Every connection of the primary unit (e.g., WAN, LAN, etc.) must be replicated across the standby unit(s) to ensure that complete replication capabilities exist.
In this scenario, each network on the Panda GateDefender Appliance (WAN, LAN, etc.) is connected to an external managed switch which has a unique VLAN assigned to each network. This deployment option consumes the least amount of network ports and provides for enhanced extensibility. Another option is to replace a single managed (VLAN capable) switch with smaller, separate switches for each network (WAN, LAN, etc.). This setup however may not be cost-effective and could be less reliable since the failure of any switch could break failover partially or completely.
In this page, there is only one box, which initially contains only one option:
Warning
HA does currently not support the automatic synchronisation of the hotspot’s database
After enabled, a second drop-down menu appears, High Availability side, that allows to configure the Panda GateDefender Appliance as master or slave. Depending on this choice, different configuration options are available. Configuring a slave unit, however, requires that a Master unit have already been set up.
For the master side, the following options are available:
A second box will appear after HA has been activated, with the list of the slaves with their IP address, a link to access their management GUI, and the possibility to delete a slave.
The HA management network.
The Panda GateDefender Appliance uses a special network to connect the master to slave unit(s): 192.168.177.0/24. If this network has already been used in other zones, none of the already defined network(s) is deleted nor any change should be made to them. Indeed, in such a case, simply assign to the HA management network a different range of IP addresses, like, e.g., 172.19.253.0/24 or 10.123.234.0/28. It is important to note that the only requirement of the management network is that it must be large enough to accommodate the master and all the slaves, so if there are only a master and a slave devices, even a network as small as 192.168.177.0/29 should suffice. The management network will be created as an interface on the GREEN network, and it will show up us such on the device or when viewing the network status.
Warning
Make sure that the management network can be reached from the current LAN setup, or it will not be possible to login to the master unit!
After the master unit has been configured, the second Panda GateDefender Appliance, that is going to be the slave, can be set up. The same procedure shall be followed for every additional slave to configure.
Warning
It is strongly suggested to make a backup of the slave unit before configuring it and saving it on a safe place, since it may become useful to restore a slave unit after it is removed from its role.
For the slave side the following are the available options.
These data will be used by the slave to retrieve from the master all the information needed and to keep the synchronisation.
Upon saving the setup, the connection to the device will be temporarily lost, since the management network is created and then the two devices (the master and the currently defined slave) begin to synchronise.
After the synchronisation process is complete, the slave itself cannot be reached anymore via its old IP address (be it its factory default or its previous GREENIP address), since it has gone in standby mode and is connected to the master only through the management network. Any change made on the primary unit (the activation of a service, the change of one setting, the deletion of a VPN user, and so on) will automatically be synced to the slave unit(s) with the exception of updates, upgrades, or device backups (these have to be performed manually on the slave unit).
Moreover, the slave Panda unit will automatically appear on the master’s list of slaves and switch to an informational-only web interface that can be accessed from the master, by following the Go to Management GUI link next to each of the entries of the list of slaves.
The RED MAC Address
During the HA failover, the RED interface MAC address is not replicated onto the slave unit. This can represent a problem if the ISP requires to use the Sticky IP setup. In this situation, the IP address assigned from the ISP is determined from the MAC address of the client’s network interface, similarly to a fixed IP asssigned from a DHCP server to a client. it may not be possible to reconnect with the slave unit. To avoid this situation, it is necessary to utilise the spoofed MAC address feature on the RED interface in order for HA to work properly. This will ensure that when the HA is activated the MAC address will carry over to the standby unit and will not require manual intervention. This can be achieved on the slave, before activating it, by ticking the option Use custom MAC address under Menubar ‣ Network ‣ Interfaces ‣ Edit main uplink ‣ Advanced settings and specifying the MAC address of the RED interface on the Master. Alternatively, the MAC address can be entered in the step 4 of the network installation wizard, writing the master’s MAC address in the Spoof MAC address with option.
Traffic monitoring is done by ntopng and can be enabled or disabled by clicking on the main switch on this page. Once traffic monitoring is enabled a link to its new administration interface appears in the lower section of the page. There, the traffic can be visualised and analysed by host, protocol, local network interface and many other types of information: All these operations can be carried out directly from the Traffic Monitoring module in The Logs and Reports Menu.
Only one option is available in this page.
Note
This option is not available on appliances with limited resources.
By default, information about the history of each host is not stored on disk. Tick the checkbox to enable per-host logging.
Warning
When this option is enabled, a number of files for each host is written on disk and updated every time that that host connects to the Panda GateDefender Appliance. With traffic monitoring active and a high network traffic, disk space may be quickly filled up and disk access may become a bottleneck in the system’s performances.
The SNMP is used to monitor network-attached devices, and can be used e.g., to control the status of the internal infrastructure.
To enable the SNMP Server is sufficient to click on the grey switch next to the Enable SNMP server label: Once done so, a few options will appear in the Settings box.
The purpose of the QoS module is to prioritise the IP traffic that is flowing through the Panda GateDefender Appliance depending on the service. In other words, the QoS is a convenient way to reserve a given amount of the available bandwidth (both incoming and outgoing) for a given service. Applications that typically need to be prioritised over bulk traffic are interactive services such as SSH or VoIP.
The QoS configuration options are arranged into three tabs: Devices, Classes, and Rules.
The Device tab is also the starting page for the QoS and is initially empty. Once populated, a table showing a list of all the Quality of Service devices appears and for each device, some parameters and the available actions are displayed.
New QoS devices can be added by clicking on the Add Quality of Service Device link above the list and by configuring a few options.
The actions available on the devices are:
- enable or disable the device. - modify the properties of the device. - remove the device.When editing a device, the same form opens as when adding a new device, in which to modify the current device’s parameters.
For every device added, four items will appear under the Classes tab: Three for high, medium, and low priority, respectively, and one for bulk traffic (see below).
This tab shows a list of all Quality of Service classes that have been created, if any. For each entry, several data are shown. New items can be added by clicking on the Add Quality of Service Class link above the list of classes. The parameters to configure are the same shown in the list:
The drop down menu allows to choose the Quality of Service device for which the class was created.
Hint
At least one QoS device must have been created before defining a QoS class.
Note
The sum of reserved percentages can not be greater than 100 per device. Moreover, the reserved bandwidth can not be higher than the limit bandwidth.
The actions available are:
- modify the properties of the device.
- move the class in the list. - remove the device.Classes can be moved up or down the list: Items closer to the top of the list are the first to be processed when the bandwidth does not suffice for all the traffic and the Panda GateDefender Appliance needs to choose which traffic should be prioritised.
The third tab displays a list of the already defined Quality of Service Rules and allows to specify which type of traffic should belong to each of the classes. To add a new Quality of Service rule click on the Add Quality of Service Rule link. In the form that will open, which is very similar to the one used to define firewall rules, several values should be configured. Many drop-down menus are employed here to ease the choices and guide through the configuration.
Note
If there is more than one service in a Quality of Service class, then all these services together will share the reserved bandwidth.
The actions available on the rules are:
- enable or disable the rule. - modify the properties of the rule. - remove the rule.