Chapter 9 – Firewall

“Firewall concepts” explains the ideas behind the components, techniques and processes that are involved in setting up and running a firewall in general and the FortiGate firewall in particular. The premise here is that regardless of how experienced someone is with firewalls as they go through the process of configuring a firewall that is new to them they are likely to come across a term or setting that they may not be familiar with even if it is only in the context of the setting they are working in at the moment. FortiGate firewall are quite comprehensive and can be very granular in the functions that they perform, so it makes sense to have a consistent frame of reference for the ideas that we will be working with.

Some examples of the concepts that will be addressed here are:

• “What is a Firewall?”
• “NAT”
• “IPv6”

 

“Firewall objects” describes the following firewall objects:

• Addressing
• Services
• Firewall Policies

“Network defense” describes various methods of defending your Network using the abilities of the FortiGate Firewall.

“GUI & CLI – What You May Not Know” helps you navigate and find the components in the Web-based Manager that you will need to build the functions. This section is does not include any in-depth explanations of what each object does as that is covered in the concepts section. This section is for showing you where you need to input your information and let you know what format the interface expects to get that information

“Building firewall objects and policies” is similar to a cookbook in that it will refer to a number of common tasks that you will likely perform to get the full functionality out of your FortiGate firewall. Because of the way that firewall are designed, performing many of the tasks requires that firewall components be set up in a number of different sections of the interface and be configured to work together to achieve the desired result. This section will bring those components all together as a straight forward series of instructions.

“Multicast forwarding” is a reference guide including the concepts and examples that are involved in the use of multicast addressing and policy forwarding as it is used in the FortiGate firewall.

Reference

This chapter provides some reference information pertaining to wireless networks.

• FortiAP web-based manager
• Wireless radio channels
• WiFi event types
• FortiAP CLI

 

FortiAP web-based manager

You can access the FortiAP unit’s built-in web-based manager. This is useful to adjust settings that are not available through the FortiGate unit’s WiFi Controller. Logging into the FortiAP web-based manager is similar to logging into the FortiGate web-based manager.

 

System Information

Status

The Status section provides information about the FortiAP unit.

 

You can:

• Select Change to change the Host Name.
• Select Update in Firmware Version to upload a new FortiAP firmware file from your computer.
• Select Change Password to change the administrator password.
• Select Backup to save the current FortiAP configuration as a file on your computer.
• Select Restore to load a configuration into your FortiAP unit from a file on your computer.

 

Network Configuration

Select DHCP or select Static and specify the IP address, netmask, and gateway IP address. Administrative Access settings affect access after the FortiAP has been authorized. By default, HTTP access needed to access the FortiAP web-based manager is enabled, but Telnet access is not enabled.

 

Connectivity

These settings determine how the FortiAP unit connects to the FortiGate WiFi controller.

 

Uplink                       Ethernet – wired connection to the FortiGate unit (default) Mesh – WiFi mesh connection

Ethernet with mesh backup support

Mesh AP SSID          Enter the SSID of the mesh root. Default: fortinet.mesh.root

Mesh AP Pass- word

Enter password for the mesh SSID.

Ethernet Bridge

Bridge the mesh SSID to the FortiAP Ethernet port.

This is available only whe Uplink is Mesh.

Packet sniffer

Capturing the traffic between the controller and the FortiAP can help you identify most FortiAP and client connection issues.

 

This section describes the following recommended packet sniffing techniques:

• CAPWAP packet sniffer
• Wireless traffic packet sniffer

 

CAPWAP packet sniffer

The first recommended technique consists of sniffing the CAPWAP traffic.

• Enable plain control on the controller and on the FortiAP to capture clear control traffic on UDP port 5246.
• On the controller:

diagnose wireless-controller wlac plain-ctl <FortiAP_serial_number> 1

 

Result:

WTP 0-FortiAP2223X11000107 Plain Control: enabled

l  On the FortiAP:

cw_diag plain-ctl 1

 

Result:

Current Plain Control: enabled

Note that some issues are related to the keep-alive for control and data channel.

• Data traffic on UDP port 5247 is not encrypted. The data itself is encrypted by the wireless security mechanism.

Data traffic is helpful to troubleshoot most of the issues related to station association, EAP authentication, WPA key exchange, roaming, and FortiAP configuration.

You can also set up a host or server to which you can forward the CAPWAP traffic:

1. Configure the host/server to which CAPWAP traffic is forwarded:

diagnose wireless-controller wlac sniff-cfg <Host_IP_address> 88888

 

Result:

Current Sniff Server: 192.168.25.41, 23352

2. Choose which traffic to capture, the interface to which the FortiAP is connected, and the FortiAP’s serial number:

diagnose wireless-controller wlac sniff <interface_name> <FortiAP_serial_number> 2

 

Result:

WTP 0-FortiAP2223X11000107 Sniff: intf port2 enabled (control and data message)

In the above syntax, the ‘2’ captures the control and data message—’1′ would capture only the control message, and ‘0’ would disable it.

3. Run Wireshark on the host/server to capture CAPWAP traffic from the controller.

• Decode the traffic as IP to check inner CAPWAP traffic.

 

Example CAPWAP packet capture

The following image shows an example of a CAPWAP packet capture, where you can see: the Layer 2 header; the sniffed traffic encapsulated into Internet Protocol for transport; CAPWAP encapsulated into UDP for sniffer purpose and encapsulated into IP; CAPWAP control traffic on UDP port 5246; and CAPWAP payload.

 

Wireless traffic packet sniffer

The second recommended technique consists of sniffing the wireless traffic directly ‘on the air’ using your FortiAP.

 

Wireless traffic packet capture

Packet captures are useful for troubleshooting all wireless client related issues because you can verify data rate and 802.11 parameters, such as radio capabilities, and determine issues with wireless signal strength, interference, or congestion on the network.

A radio can only capture one frequency at a time; one of the radios is set to sniffer mode depending on the traffic or channel required. You must use two FortiAPs to capture both frequencies at the same time.

• Set a radio on the FortiAP to monitor mode.

iwconfig wlan10

 

Result:

wlan10 IEEE 802.11na   ESSID:””

Mode:Monitor Frequency:5.18 GHz Access Point: Not-Associated

• The capture file is stored under the temp directory as wl_sniff.pcap

 

/tmp/wl_sniff.cap

• Remember that the capture file is only stored temporarily. If you want to save it, upload it to a TFTP server before rebooting or changing the radio settings.
• The command cp wl_sniff.cap newname.pcap allows you to rename the file.
• Rather than TFTP the file, you can also log in to the AP and retrive the file via the web interface. Move the file using the command: mv name /usr/www You can verify the file was moved using the command cd/usr/www and then browsing to: <fortiAP_ IP>/filename

 

Syntax

The following syntax demonstrates how to set the radio to sniffer mode (configurable from the CLI only). Sniffer mode provides options to filter for specific traffic to capture. Notice that you can determine the buffer size, which channel to sniff, the AP’s MAC address, and select if you want to sniff the beacons, probes, controls, and data channels.

 

configure wireless-controller wtp-profile edit <profile_name>

configure <radio>

set mode sniffer

set ap-sniffer-bufsize 32 set ap-sniffer-chan 1

set ap-sniffer-addr 00:00:00:00:00:00 set ap-sniffer-mgmt-beacon enable

set ap-sniffer-mgmt-probe enable set ap-sniffer-mgmt-other enable set ap-sniffer-ctl enable

set ap-sniffer-data enable end

end

 

Once you’ve performed the previous CLI configuration, you’ll be able to see the packet sniffer mode selected in the GUI dashboard under WiFi & Switch Controller > FortiAP Profiles and WiFi & Switch Controller > Managed FortiAPs. Bear in mind that if you change the mode from the GUI, you’ll have to return to the CLI to re-enable the Sniffer mode.

 

To disable the sniffer profile in the CLI, use the following commands:

 

config wireless-controller wtp-profile edit <profile_name>

config <radio>

set ap-sniffer-mgmt-beacon disable set ap-sniffer-mgmt-probe disable set ap-sniffer-mgmt-other disable set ap-sniffer-ctl disable

set ap-sniffer-data disable end

end

 

If you change the radio mode before sending the file wl_sniff.cap to an external

TFTP, the file will be deleted and you will lose your packet capture.

In the following section, you will learn basic troubleshooting techniques for a secure Fortinet wireless LAN

including:

• strategies for troubleshooting Fortinet wireless devices
• how to avoid common misconfigurations
• solutions to connectivity issues
• capturing and analyzing wireless traffic
• wireless debug commands

 

The goal of this document is to provide you with practical knowledge that you can use to troubleshoot the FortiOS wireless controller and FortiAP devices. This includes how to use tools and apply CLI commands for maintenance and troubleshooting of your wireless network infrastructure, analyze problems per OSI layer, explore diagnostics for commissioning issues regarding at-client and access point connectivity problems, and understand the packet sniffer technique as a strong troubleshooting tool.

The content is divided as follows: Signal strength issues

Throughput issues Connection issues General problems Packet sniffer

Useful debugging commands

 

Signal strength issues

Poor signal strength is possibly the most common customer complaint. Below you will learn where to begin identifying and troubleshooting poor signal strength, and learn what information you can obtain from the customer to help resolve signal strength issues.

 

Asymmetric power issue

Asymmetric power issues are a typical problem. Wireless is two-way communication; high power access points (APs) can usually transmit a long distance, however, the client’s ability to transmit is usually not equal to that of the AP and, as such, cannot return transmission if the distance is too far.

 

Measuring signal strength in both directions

To solve an asymmetric power issue, measure the signal strength in both directions. APs usually have enough power to transmit long distances, but sometimes battery-powered clients have a reply signal that has less power, and therefore the AP cannot detect their signal.

It is recommended that you match the transmission power of the AP to the least powerful wireless client—around 10 decibels per milliwatt (dBm) for iPhones and 14dBm for most laptops.

Even if the signal is strong enough, other devices may be emitting radiation as well, causing interference. To identify the difference, read the client Rx strength from the FortiGate GUI (under Monitor > WiFi Client Monitor) or CLI.

The Signal Strength/Noise value provides the received signal strength indicator (RSSI) of the wireless client. For example, A value of -85dBm to -95dBm is equal to about 10dB levels; this is not a desirable signal strength. In the following screenshot, one of the clients is at 18dB, which is getting close to the perimeter of its range.

The Signal Strength/Noise value received from the FortiAP by clients, and vice versa, should be within the range of -20dBm to -65dBm.

You can also confirm the transmission (Tx) power of the controller on the AP profile (wtp-profile) and the FortiAP (iwconfig), and check the power management (auto-Tx) options.

 

Controller configured transmitting power – CLI:

config wireless-controller wtp-profile config <radio>

show

(the following output is limited to power levels)

auto-power-level : enable auto-power-high : 17

auto-power-low : 10

 

Actual FortiAP transmitting power – CLI:

iwconfig wlan00

 

Result:

wlan00 IEEE 802.11ng ESSID:”signal-check”

Mode:Master Frequency:2.412 GHz  Access Point:<MAC add> Bit Rate:130 Mb/s Tx-Power=28 dBm

 

Using FortiPlanner PRO with a site survey

The most thorough method to solve signal strength issues is to perform a site survey. To this end, Fortinet offers the FortiPlanner, downloadable at http://www.fortinet.com/resource_center/product_downloads.html.

 

Sample depiction of a site survey using FortiPlanner

The site survey provides you with optimal placement for your APs based on the variables in your environment. You must provide the site survey detailed information including a floor plan (to scale), structural materials, and more. It will allow you to place the APs on the map and adjust the radio bands and power levels while providing you with visual wireless coverage.

Below is a list of mechanisms for gathering further information on the client for Rx strength. The goal is to see how well the client is receiving the signal from the AP. You can also verify FortiAP signal strength on the client using WiFi client utilities, or third party utilities such as InSSIDer or MetaGeek Chanalyzer. You can get similar tools from the app stores on Android and iOS devices.

• Professional Site Survey software (Ekahau, Airmagnet survey Pro, FortiPlanner)
• InSSIDer
• On Windows: “netsh wlan show networks mode=bssid” (look for the BSSID, it’s in % not in dBm!)
• On MacOS: Use the “airport” command:

“/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A/Resources/airport” airport –s |

grep <the_bssid> (live scan each time)

 

l  On Droid: WiFiFoFum

 

Frequency interference

If the wireless signal seems to be strong but then periodically drops, this may be a symptom of frequency interference. Frequency interference is when another device also emits radio frequency using the same channel, co-channel, or adjacent channel, thereby overpowering or corrputing your signal. This is a common problem on a 2.4GHz network.

There are two types of interference: coherent and non-coherent.

• Coherent interference: a result of another device using the same channel as your AP, or poor planning of a wireless infrastructure (perhaps the other nearby APs are using the same channel or the signal strength is too high).
• Non-coherent interference: a result of other radio signals such as bluetooth, microwave, cordless phone, or (as in medical environments) x-ray machines.

Most common and simple solution for frequency interference is to change your operation channel. Typically, the channel can be set from 1 to 11 for the broadcast frequency, although you should always use channels 1, 6, and 11 on the 2.4GHz band.

Another solution, if it’s appropriate for your location, is to use the 5GHz band instead.

 

MetaGeek Chanalyzer

You can perform a site survey using spectrum analysis at various points in your environment looking for signal versus interference/noise. MetaGeek Chanalyzer is an example of a third party utility which shows a noise threshold.

Note that a signal of -95dBm or less will be ignored by Fortinet wireless adapters.

 

Throughput issues

Sometimes communication issues can be caused by low performance.

 

Testing the link

You can identify delays or lost packets by sending ping packets from your wireless client. If there is more than 10ms of delay, there may be a problem with your wireless deployment, such as:

• a weak transmit signal from the client (the host does not reach the AP)
• the AP utilization is too high (your AP could be saturated with connected clients)
• interference (third party signal could degrade your AP or client’s ability to detect signals between them)
• weak transmit power from the AP (the AP does not reach the host) — not common in a properly deployed network, unless the client is too far away

Keep in mind that water will also cause a reduction in radio signal strength for those making use out of outdoor APs or wireless on a boat.

Support For Location Based Services

FortiOS supports location-based services by collecting information about WiFi devices near FortiGate-managed access points, even if the devices don’t associate with the network.

Overview

• Configuring location tracking
• Viewing device location data on the FortiGate unit

 

Overview

WiFi devices broadcast packets as they search for available networks. The FortiGate WiFi controller can collect information about the interval, duration, and signal strength of these packets. The Euclid Analytics service uses this information to track the movements of the device owner. A typical application of this technology is to analyze shopper behavior in a shopping center. Which stores do people walk past? Which window displays do they stop to look at? Which stores do they enter and how long do they spend there? The shoppers are not personally identified, each is known only by the MAC address of their WiFi device.

After enabling location tracking on the FortiGate unit, you can confirm that the feature is working by using a specialized diagnostic command to view the raw tracking data. The Euclid Analytics service obtains the same data in its proprietary format using a JSON inquiry through the FortiGate unit’s web-based manager interface.

 

Configuring location tracking

You can enable location tracking in any FortiAP profile, using the CLI. Location tracking is part of location-based services. Set the station-locate field to enable. For example:

config wireless-controller wtp-profile edit “FAP220B-locate”

set ap-country US

config platform set type 220B

end

config lbs

set station-locate enable end

end

 

Automatic deletion of outdated presence data

The FortiGate generates a log entry only the first time that station-locate detects a mobile client. No log is generated for clients that have been detected before. To log repeat client visits, previous station presence data must be deleted (flushed). The sta-locate-timer can flush this data periodically. The default period is 1800 seconds (30 minutes). The timer can be set to any value between 1 and 86400 seconds (24 hours). A setting of 0 disables the flush, meaning a client is logged only on the very first visit.

The timer is one of the wireless controller timers and it can be set in the CLI. For example:

config wireless-controller timers set sta-locate-timer 1800

end

 

The sta-locate-timer should not be set to less than the sta-capability-timer (default 30 seconds) because that could cause duplicate logs to be generated.

 

Viewing device location data on the FortiGate unit

You can use the FortiGate CLI to list located devices. This is mainly useful to confirm that the location data feature is working, You can also reset device location data.

 

To list located devices

diag wireless-controller wlac -c sta-locate

 

To reset device location data

diag wireless-controller wlac -c sta-locate-reset

 

Example output

The following output shows data for three WiFi devices.

FWF60C3G11004319 # diagnose wireless-controller wlac -c sta-locate

sta_mac vfid rid base_mac freq_lst frm_cnt frm_fst frm_last intv_sum intv2_sum intv3_ sum intv_min intv_max signal_sum signal2_sum signal3_sum sig_min sig_max sig_fst sig_last ap

00:0b:6b:22:82:61 0

FAP22B3U11005354 0 0 00:09:0f:f1:bb:e4 5745 257 708 56 651 1836 6441 0 12 -21832

1855438 -157758796 -88 -81 -84 -88 0

00:db:df:24:1a:67 0

FAP22B3U11005354 0 0 00:09:0f:f1:bb:e4 5745 42 1666 41 1625 97210 5831613 0 60 -3608

310072 -26658680 -90 -83 -85 -89 0

10:68:3f:50:22:29 0

FAP22B3U11005354 0 0 00:09:0f:f1:bb:e4 5745 102 1623 58 1565 94136 5664566 0 60 -8025

631703 -49751433 -84 -75 -78 -79 0

The output for each device appears on two lines. The first line contains only the device MAC address and the VLAN ID. The second line begins with the ID (serial number) of the FortiWiFi or FortiAP unit that detected the device, the AP’s MAC address, and then the fields that the Euclid service uses. Because of its length, this line wraps around and displays as multiple lines.

 

Using a FortiWiFi unit as a client

A FortiWiFi unit by default operates as a wireless access point. But a FortiWiFi unit can also operate as a wireless client, connecting the FortiGate unit to another wireless network.

• Use of client mode
• Configuring client mode

 

Use of client mode

In client mode, the FortiWiFi unit connects to a remote WiFi access point to access other networks or the Internet. This is most useful when the FortiWiFi unit is in a location that does not have a wired infrastructure.

For example, in a warehouse where shipping and receiving are on opposite sides of the building, running cables might not be an option due to the warehouse environment. The FortiWiFi unit can support wired users using its Ethernet ports and can connect to another access point wirelessly as a client. This connects the wired users to the network using the 802.11 WiFi standard as a backbone.

Note that in client mode the FortiWiFi unit cannot operate as an AP. WiFi clients cannot see or connect to the FortiWifi unit in Client mode.

 

FortiWiFi unit in Client mode

Using a FortiWiFi unit as a client

FortiGate                                     FortiAP

>))

Wired  clients

Configuring client mode

To set up the FortiAP unit as a WiFi client, you must use the CLI. Before you do this, be sure to remove any AP WiFi configurations such as SSIDs, DHCP servers, policies, and so on.

 

To configure wireless client mode

1. Change the WiFi mode to client.

In the CLI, enter the following commands:

config system global

set wireless-mode client end

Respond “y” when asked if you want to continue. The FortiWiFi unit will reboot.

 

2. Configure the WiFi interface settings.

For example, to configure the client for WPA-Personal authentication on the our_wifi SSID with passphrase

justforus, enter the following in the CLI:

config system interface edit wifi

set mode dhcp

config wifi-networks edit 0

set wifi-ssid our_wifi

set wifi-security wpa-personal set wifi-passphrase “justforus”

end

end

The WiFi interface client_wifi will receive an IP address using DHCP.

 

3. Configure a wifi to port1 policy.

You can use either CLI or web-based manager to do this. The important settings are:

Incoming Interface (srcintf)     wifi

Source Address (srcaddr)       all

Outgoing Interface (dstintf)     port1

Destination Address

(dstaddr)

all

Schedule                                    always

Service                                       ALL

Action                                         ACCEPT

Enable NAT                                Selected