The Services Menu

The 4i Edge X includes many useful services to prevent threats and to configure the networks and the running daemons, whose activation and set up is explained in this section. Among them there are the DHCP server for internal zones, the intrusion detection system, and the Serial Port service. The available services appear as items in the sub-menu list on the left-hand side of the screen.

• DHCP server–DHCP server for automatic IP assignment

• Dynamic DNS - Client for dynamic DNS providers such as DynDNS (for home / small office use)

• Time server–enable and configure the NTP time server, set the time zone, or update the time manually

• Intrusion Prevention System–configuration of the IPS snort

• SNMP Server–enable or disable support for the Simple Network Management Protocol

• Quality of Service–IP traffic prioritisation

• Serial port–configure the serial port

DHCP server

The DHCP server is used by the clients (both workstations and servers) in the zones controlled by the 4i Edge X to receive an IP address (called lease), either dynamic or a fixed lease, and communicate with other local and remote devices.

The DHCP server configuration consists of three pages, namely Server configuration, Fixed leases, and Dynamic leases.

Server configuration

The DHCP server on an 4i Edge X can be enabled on each active zone independently. For each of the zones enabled on the 4i Edge X, this page show one checkbox, hence at least the Enable DHCP server on GREEN interface option appears. There are corresponding checkboxes for the ORANGE and BLUE zone if they are activated.

At the bottom of the page, there is a textfield, labelled Custom configuration lines, that can be used by advanced users to write custom configuration lines to be added to the dhcpd.conf file (e.g., custom routes to subnets), like this example shows.

Warning

The custom configuration lines must adhere to the syntax of the /etc/dhcpd.conf file–check the manual page dhcpd.conf (5) or see it online at https://linux.die.net/man/5/dhcpd.conf, since they are not checked for errors and are inserted verbatim in the configuration file. Any typo or mistake might prevent the DHCP server from starting correctly!

To customise the DHCP parameter for each zone, tick the respective checkbox. A panel labelled Settings will appear: click on it to show the available options.

Settings

Mode

In this dropdown you can select whether you wish to configure the selected zone as a DHCP Server or Relay

DHCP Server

Start address, End address

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 these two fields are left blank, the whole IP range of the zone will be used to assign dynamic leases.

Hint

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.

Allow only fixed leases

Tick this checkbox to use fixed leases only. No dynamic lease will be assigned.

Treat infinite leases as reserved

Tick this checkbox and the server will automatically reserve leases allocated to clients which requested an infinite lease-time.

Default lease time, Max lease time

The default and the maximum time in minutes before the assignment of each lease expires and the client requests a new lease from the DHCP server.

Domain name suffix

The default domain name suffix that is passed to the clients and that will be used for local domain searches.

Default Gateway

The default gateway that the clients in the zone will used. If left blank, the default gateway is the 4i Edge X itself.

Primary DNS, Secondary DNS

The DNS used by the clients. Since the 4i Edge X contains a caching DNS server, the default value is the firewall’s own IP address in the respective zone, though a second server or even the primary value can be changed.

Example SRV-1 - PXE boot and dhcpd.conf configuration.

The customisation of the DHCP server proves useful in different networks configuration.

One common use case is for VoIP telephones that need to retrieve their configuration files from an HTTP server at boot time In this case, the files may also reside on the 4i Edge X, so the configuration of the tftp server can be passed as extra lines like the following:

option tftp-server-name "http://192.168.0.15";
option bootfile-name "download/voip/{mac}.html";

Remember to replace 192.168.0.15 with the correct IP address and the download/voip/{mac}.html string with the correct path. Additional information about the available options can be found in the dhcpd(5) man page.

Primary NTP server, Secondary NTP server

The NTP servers used by the clients, to keep the clocks synchronised. Leave blank to use the 4i Edge X's default NTP server.

Primary WINS server address, Secondary WINS server address

The WINS servers used by the clients. This option is only needed for the Microsoft Windows networks that use WINS.

Once done, click on the Save button at the bottom of the page, then on the Apply button in the green callout that will appear to restart the DHCPD server with the new configuration.

DHCP Relay

Relay server zone

Here you can select the zone which you wish to configure as a DHCP relay.

Relay address

Enter the IP address to relay (forward) the DHCP requests received on the configured zone.

Append agent option fields

Append an agent option field to each request before forwarding it to the server. Agent option fields in responses sent from servers to clients will be stripped before forwarding such responses back to the client.

Fixed leases

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 a service (like, e.g., a VPN server or a code repository) or devices like printers or scanners.

A fixed lease is also called Static IP Address, since a device will always receive the same IP address when requesting a lease from the DHCP server.

This page contains the list of all the fixed leases defined in the local networks, providing several information about that lease: The device’s MAC Address and the assigned IP address, a remark, and the available actions.

By clicking on the Add a fixed lease button, a static IP address can be assigned to a device. 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 (client) 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:

MAC address

The client’s MAC address.

IP address

The IP address that will always be assigned to the client.

Remark

An optional description of the device receiving the lease.

Advanced options

In this panel appear three additional options.

Next address

The address of the TFTP server. This and the next two options are useful only in a few cases (see below for an example).

Filename

The boot image file name. Option needed only for thin clients or network boot.

Root path

The path of the boot image file.

Enabled

If this checkbox is not ticked, the fixed lease will be stored but not written down to the file dhcpd.conf.

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.

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 leases 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 2019/06/11 13:00:21;
ends 5 2019/06/14 01:00:21;
binding state active;
next binding state free;
hardware ethernet 00:14:22:b1:09:9b;
}

Dynamic leases

After the DHCP server has been activated, and at least one client has received a (dynamic) IP address, the table in this page will feature the list of the clients, with these additional information: assigned dynamic IP addresses, the MAC address of the connecting device and its hostname, the expiry date and time, and the status, which can be either expired or active.

Dynamic DNS

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 4i Edge X includes a dynamic DNS client for 33 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.

New accounts can be created by clicking on the Add provider link, providing the following parameters:

Enabled

Tick this checkbox to enable the account, which is the default.

Service

The drop-down menu shows the available DDNS providers.

Hostname and Domain

The hostname and domain as registered with the DDNS provider, for instance “example” and “myddns.org”

Username and Password

The credentials given from dynamic DNS provider to access the service.

Note

The dynamic DNS provider only resolves the domain name and not the associated services. If some service must be accessed from the Internet to the 4i Edge X or to some host behind the 4i Edge X, it is necessary to set up some port forwarding rules (see Menubar ‣ Firewall ‣ Port forwarding / NAT).

After making a change in the configuration, click on the Apply now button to apply the change to the appliance.

If necessary to remove a DDNS account, you can simply click on the trash icon on the right side of the corresponding entry.

Time server

The 4i Edge X uses NTP to keep its system time synchronised with time servers on the Internet. There is only one settings, displayed in the Network time server panel.

Network time server

A number of time server hosts on the Internet are preconfigured and used by the system, along with the time zone. Available options are the following.

Override default NTP servers

Tick the checkbox to replace the default NTP servers. This might prove necessary when running a setup that does not allow the 4i Edge X to reach the Internet. Several time servers addresses can be supplied, one per line, in the small form that will show up; each of them will be written in the configuration file, as value of the server option. For better performance, at least two time server should be provided here.

Hint

Each custom time server can be written as a hostname or IP address. Entries can be also vendor-specific, like e.g., 0.endian.pool.ntp.org.

Note

If for some reasons the 4i Edge X's clock is not synchronised anymore with the NTP servers and the difference between them is high, there is the chance that a manual synchronisation be necessary. This can be done either by clicking on the Synchronize now button, or in the Localization options, under the System Settings (System ‣ Settings ‣ Localization), by manually entering the correct time and date.

IDS/IPS

The 4i Edge X includes the well known Intrusion Detection (IDS) and Prevention (IPS) system snort, which can identify advanced threats using deep-packet inspection technology to analyze network packets.

Settings

If snort is not active, a grey switch Disabled appears on the page and can be clicked on to start the service. After a short interval, the page will contain some options to configure the service.

Intrusion Prevention System settings

This panel allows to define the automatic download and installation of the snort rules.

Operation mode

Here you can toggle the operating mode between IDS mode or IPS mode.

• IDS. In this mode, the 4i Edge X will inspect traffic in passive mode in order to maximize throughput and minimize traffic disruptions. When this option is selected, you will see the following option:

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Zones where IDS will be enabled

Here you can select the internal network zones which are enabled and active within the 4i Edge X for which you want to activate the IDS inspection

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• IPS. In this mode, the 4i Edge X will inspect traffic inline in order to provide maximum security at the expense of decreased throughput. This mode provides the capability to instantly block traffic for any IPS enabled signatures. When using this mode, a user must enable IPS inspection within the various components of the firewall for each rule required.

Automatically fetch SNORT Rules

Ticking this box will let the 4i Edge X automatically download the snort rules from the Endian Network.

Note

If the 4i Edge X 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.

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SNORT rules update schedule

The frequency of download of the rules: A drop-down menu allows to choose one of the Hourly, Daily, Weekly, or Monthly options. This option appears only if the previous option has been activated.

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Rules last updated

An informative message about the last time rules have been manually downloaded, like for example: 2019-08-01 10:48:31

Update rules now

By clicking on this button, the signatures for the IPS service will be immediately downloaded from the emeringthreats.net web site.

SNORT rules

Pick one file from the file selection window that opens upon clicking the button next to this label.

Upload custom rules

Click on this button to upload the file and use it with snort.

Rules

The list of rulesets that are stored on the 4i Edge X appears in this page, along with the number of rules they contain and the actions that can be done on them.

It is possible to edit each ruleset independently, by clicking on the icon in the rightmost column, Actions, but when at least one ruleset is selected, atop the table a few buttons will appear, allowing to carry out bulk actions on all the selected rulesets at once. On the right-hand side of the button, a number in a green circle shows how many rulesets are currently selected: Click on it to select all (including those in other pages) or none of the datasets.

The rule policies in snort.

By default, the policy for all the rulesets is set to alert, shown by the icon. This means that whenever a flow of traffic will match the corresponding rule or ruleset, the traffic will be allowed to pass and the intrusion attempt will be logged.

This behaviour can be changed by clicking on the alert icon to toggle the policy into block, shown by the icon , with the result that the intrusion attempt will be blocked, but no message will be recorded in the log files.

After a policy of a rule or of a whole ruleset has been changed, it is necessary to click on the Apply button, for the changes to be applied.

After clicking on the Edit button, the list of the rules included in the selected ruleset(s) is shown, which can be narrowed down by entering some terms in the text box next to the Search label. To go back to the previous page, click on the Back to rules link on the top left corner of the table.

Warning

Turning on the IPS only implies that snort is running, but not that it is already used to filter the traffic. Indeed, the IPS is used only on those firewall rules, defined in the various Firewall configuration pages, that are configured with the Allow with IPS Filter policy .

See also

The Firewall Menu

Menubar ‣ Firewall

A visual, step-by-step tutorial to set up IPS.

SNMP Server

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 Disabled grey switch. Once done so, a few options will appear in the Settings panel.

Settings

Community String

A key that is needed to read the data with an SNMP client.

Location

An identification string that can be set to anything, but it is suggested that it describe the location of the 4i Edge X.

Override global notification email address

The SNMP Server requires to configure an e-mail address as the system contact, and the global e-mail address provided during the installation procedure is used by default. In order to use a custom e-mail address, tick the checkbox to activate the next option.

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System contact email address

Write the e-mail address of the administrator to be contacted.

Quality of Service

The purpose of the QoS module is to prioritise the IP traffic that is flowing through the 4i Edge X 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.

Tagging

The fourth page is different from the others as it is used to classify and prioritise traffic. In other words, the traffic can be marked or tagged to allow external devices to handle it accordingly. This is particularly useful in a scenario with limited bandwidth and the uplink device, e.g., a modem, can only prioritise traffic based on TOS or DSCP flags in the packets. When clicking on the Add new rule link the editor opens, which is similar to the one under the Rules page. These are the available options:

Source

Type

Choose from the drop-down menu the traffic source, either a Zone or interface, a network or an IP, or a MAC address. Depending on this choice, different values can be specified: A zone or interface from the available ones from those that will be displayed, or one or more IP addresses, networks, or MAC addresses. The default value is <ANY>, meaning the rule will be applied to all traffic.

Destination

Type

Choose from the drop-down menu the traffic destination, either a Zone or interface, a network or an IP. Depending on this choice, different values can be specified: A zone or interface from the available ones from those that will be displayed, or one or more IP addresses or networks.

Service/Port

Service

The service that the rule should match.

Hint

User defined permits to specify a custom protocol and the ports to block, an option that proves useful when running services on ports different from the standard ones.

Protocol

The type of traffic that is interested by the rule: TCP, UDP, TCP+UDP, ESP, GRE, and ICMP. TCP and UDP are the most used, GRE is used by tunnels, ESP by IPsec, and ICMP by the ping and traceroute commands.

Destination port

The destination port for the rule.

Note

There exist dozens predefined services that can be chosen from the drop-down menus and should suffice to cover the most use cases. An user defined combination of port and protocol should be used only if a service is not running on a standard port (e.g., the SSH server listens to port 2345 or the web server runs on port 7981) or if a service, not included in the list, is using a particular port.

TOS/DSCP

Type

Choose from the drop-down menu which tag to use to mark the traffic: a TOS flag, a DSCP class or a DSCP value. Depending on the choice, one of the following three options will appear.

Tag traffic with the following TOS flag

This dropdown appears only when TOS is chosen in the Type option above. It allows to define the TOS flag that will be set in all matching packets.

Tag traffic with the following DSCP class

This dropdown appears when choosing DSCP Class in the Type option above. It allows to define the DSCP class that will be set in all matching packets.

Tag traffic with the following DSCP value

This field appears only when DSCP value is chosen in the Type option above. It allows to enter a custom value for DSCP, that will be set in all matching packets.

Enabled

Tick the checkbox to enable the rule.

Comment

A comment to identify the rule.

Serial Port

The Serial Port pages allow to configure the 4i Edge X‘s serial port as either serial console or serial server in three different operational modalities: Server, client, or console. The configuration options are grouped into two pages, Port configuration and Serial server.

Port Configuration

In this page it is possible to configure and edit the available serial ports on the 4i Edge X, by clicking on the corresponding icon.

Change serial port configuration

The available options are:

Serial port

This is always ttyS1, since it is the only available serial port.

Remark

A comment about the serial port’s configuration.

Enabled

Tick the checkbox to enable the serial port.

Enable console

By ticking the checkbox, it will be possible to connect to the 4i Edge X via the serial console.

Hint

The Serial Server page allows no configuration if this option is enabled.

Serial Port standard

Choose the type of the serial port from the drop-down menu. Available options are: RS-232, RS-485, and RS-422.

Baudrate

The speed in baud of the serial port. Available values can be selected from the drop-down menu.

Hint

Modern appliances use a speed of 115,200 baud.

Parity

Choose the parity of the communication from the drop-down menu among the available values: None, Even, and Odd.

Data bits

Select the data bits from the drop-down menu. Available values are 5, 6, 7 and 8.

Stop bits

The stop bits value, either 1 or 2, chosen from the drop-down menu.

Advanced settings

When the standard used is rs232, an additional option can be configured in this panel.

Flow control

Choose the type of control to be applied to the traffic flow. Possible values are none, ctsrts, and xonxoff.

Serial Server

This page carries only an empty table if in Port Configuration the Enable console option has been ticked; no configuration is allowed because the port is used as a serial port to access the system.

The table shows the configuration–initially displaying only the name of the serial port–of the serial server. When clicking on the edit icon it is possible to configure the port as a serial server.

In this setup, the serial port of the 4i Edge X can be accessed over a TCP connection: by installing on a workstation a client software supporting remote virtual server port, the 4i Edge X can be accessed like a direct cable connection were in place:

[ Virtual Serial ] --> [ Client (Windows, Linux) ] --> TCP
connection (via Internet or VPN) --> [ 4i ] --> [ Physical Serial
Port ]

Change serial port configuration

Enabled

Tick the checkbox to enable the serial port.

Remark

A comment about the configuration.

Operation mode

Choose from the drop-down menu one of the available operation modes: Raw Client and Raw Server.

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Server IP

This option only appears when Raw Client is selected. Supply one IP address to which to forward the traffic when connecting to the serial port.

Server Port

This option only appears when Raw Client is selected. Supply one port to which the traffic through the serial port will be directed.

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TCP Port

This option only appears when Raw Server is selected. Provide a TCP port that will allow serial connection.

Advanced settings

Enable debug mode

By ticking this checkbox more information about connections through serial console will be logged: This proves useful for e.g., troubleshooting.