Category Archives: FortiOS 5.4 Handbook

The complete handbook for FortiOS 5.4

Adding disclaimer messages to explicit proxy policies

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Adding disclaimer messages to explicit proxy policies

This feature allows you to create user exceptions for specific URL categories (including warning messages) based on user groups. The Disclaimer Options are configured under Policy & Objects > Explicit Proxy Policy.

You can also configure a disclaimer for each Authentication Rule by setting Action to Authenticate.

 

Disclaimer explanations

  • Disable: No disclaimer (default setting).
  • By Domain: The disclaimer will be displayed on different domains. The explicit web proxy will check the referring header to mitigate the javascript/css/images/video/etc page.
  • By Policy: The disclaimer will be displayed ifa the HTTP request matches a different explicit firewall policy.
  • By User: The disclaimer will be displayed when a new user logs on.

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Proxy chaining (web proxy forwarding servers)

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Proxy chaining (web proxy forwarding servers)

For the explicit web proxy you can configure web proxy forwarding servers to use proxy chaining to redirect web proxy sessions to other proxy servers. Proxy chaining can be used to forward web proxy sessions from the FortiGate unit to one or more other proxy servers on your network or on a remote network. You can use proxy chaining to integrate the FortiGate explicit web proxy with an web proxy solution that you already have in place.

A FortiGate unit can forward sessions to most web proxy servers including a remote FortiGate unit with the explicit web proxy enabled. No special configuration of the explicit web proxy on the remote FortiGate unit is required.

You can deploy the explicit web proxy with proxy chaining in an enterprise environment consisting of small satellite offices and a main office. If each office has a FortiGate unit, users at each of the satellite offices can use their local FortiGate unit as an explicit web proxy server. The satellite office FortiGate units can forward explicit web proxy sessions to an explicit web proxy server at the central office. From here the sessions can connect to web servers on the Internet.

FortiGate proxy chaining does not support authenticating with the remote forwarding server.

 

Adding a web proxy forwarding server

To add a forwarding server, select Create New in the Web Proxy Forwarding Servers section of the Explicit Proxy page by going to Network > Explicit Proxy.

Server Name             Enter the name of the forwarding server.

Proxy Address         Enter the IP address of the forwarding server.

Proxy Address Type

Select the type of IP address of the forwarding server. A forwarding server can have an FQDN or IP address.

 

Port

Enter the port number on which the proxy receives connections. Traffic leaving the FortiGate explicit web proxy for this server has its destination port number changed to this number.
Server Down action

Select what action the explicit web proxy to take if the forwarding server is down.

 

Block means if the remote server is down block traffic.

 

Use Original Server means do not forward traffic to the forwarding sever but instead forward it from the FortiGate to its destination. In other words operate as if there is no forwarding server configured.

 

Enable Health

Monitor                     Select to enable health check monitoring and enter the address of a remote site. See

 

Health Check

Monitor Site

“Web proxy forwarding server monitoring and health checking”.

 

Use the following CLI command to add a web proxy forwarding server named fwd-srv at address proxy.example.com and port 8080.

 

config web-proxy forward-server

 

edit fwd-srv

set addr-type fqdn

set fqdn proxy.example.com set port 8080

end

 

Web proxy forwarding server monitoring and health checking

By default, a FortiGate unit monitors web proxy forwarding server by forwarding a connection to the remote server every 10 seconds. If the remote server does not respond it is assumed to be down. Checking continues and when the server does send a response the server is assumed to be back up. If you configure health checking, every 10 seconds the FortiGate unit attempts to get a response from a web server by connecting through the remote forwarding server.

You can configure health checking for each remote server and specify a different website to check for each one. If the remote server is found to be down you can configure the FortiGate unit to block sessions until the server comes back up or to allow sessions to connect to their destination, bypassing the remote forwarding server. You cannot configure the FortiGate unit to fail over to another remote forwarding server.

Configure the server down action and enable health monitoring from the web-based manager by going to Network > Explicit Proxy, selecting a forwarding server, and changing the server down action and changing the health monitor settings.

Use the following CLI command to enable health checking for a web proxy forwarding server and set the server down option to bypass the forwarding server if it is down.

config web-proxy forward-server edit fwd-srv

set healthcheck enable

set monitor http://example.com set server-down-option pass

end

 

Grouping forwarding servers and load balancing traffic to them

You can add multiple web proxy forwarding servers to a forwarding server group and then add the server group to an explicit web proxy policy instead of adding a single server. Forwarding server groups are created from the FortiGate CLI but can be added to policies from the web-based manager (or from the CLI).

When you create a forwarding server group you can select a load balancing method to control how sessions are load balanced to the forwarding servers in the server group. Two load balancing methods are available:

  • Weighted load balancing sends more sessions to the servers with higher weights. You can configure the weight for each server when you add it to the group.
  • Least-session load balancing sends new sessions to the forwarding server that is processing the fewest sessions.

When you create a forwarding server group you can also enable affinity. Enable affinity to have requests from the same client processed by the same server. This can reduce delays caused by using multiple servers for a single multi-step client operation. Affinity takes precedence over load balancing.

You can also configure the behavior of the group if all of the servers in the group are down. You can select to block traffic or you can select to have the traffic pass through the FortiGate explicit proxy directly to its destination instead of being sent to one of the forwarding servers.

Use the following command to add a forwarding server group that users weighted load balancing to load balance traffic to three forwarding servers. Server weights are configured to send most traffic to server2. The group has affinity enabled and blocks traffic if all of the forward servers are down:

config web-proxy forward-server edit server_1

set ip 172.20.120.12 set port 8080

next

edit server_2

set ip 172.20.120.13 set port 8000

next

edit server_3

set ip 172.20.120.14 set port 8090

next end

config web-proxy forward-server-group edit New-fwd-group

set affinity enable set ldb-method weight

set group-down-option block config server-list

edit server_1 set weight 10

next

edit server_2 set weight 40

next

edit server_3 set weight 10

next

end

 

Adding proxy chaining to an explicit web proxy policy

You enable proxy chaining for web proxy sessions by adding a web proxy forwarding server or server group to an explicit web proxy policy. In a policy you can select one web proxy forwarding server or server group. All explicit web proxy traffic accepted by this security policy is forwarded to the specified web proxy forwarding server or server group.

 

To add an explicit web proxy forwarding server – web-based manager:

1. Go to Policy & Objects > Explicit Proxy Policy and select Create New.

2. Configure the policy:

 

Explicit Proxy Type                  Web

Source Address                        Internal_subnet

Outgoing Interface                   wan1

Destination Address                 all

Schedule                                    always

Action                                         ACCEPT

Web Proxy Forwarding

Server

Select, fwd-srv

3. Select OK to save the security policy.

 

To add an explicit web proxy forwarding server – CLI:

1. Use the following command to add a security policy that allows all users on the 10.31.101.0 subnet to use the explicit web proxy for connections through the wan1 interface to the Internet. The policy forwards web proxy sessions to a remote forwarding server named fwd-srv

config firewall explicit-proxy-policy edit 0

set proxy web

set dstintf wan1

set scraddr Internal_subnet set dstaddr all

set action accept set schedule always

set webproxy-forward-server fwd-srv end


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Other explicit web proxy options

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Other explicit web proxy options

You can change the following explicit web proxy options as required by your configuration.

 

HTTP port, HTTPS port, FTP port, PAC port

The TCP port that web browsers use to connect to the explicit proxy for HTTP, HTTPS, FTP and PAC services. The default port is 8080 for all services. By default HTTPS, FTP. and PAC use the same port as HTTP. You can change any of these ports as required. Users configuring their web browsers to use the explicit web proxy should add the same port numbers to their browser configurations.

 

Proxy FQDN             Enter the fully qualified domain name (FQDN) for the proxy server. This is the domain name to enter into browsers to access the proxy server.

 

Max HTTP request length

Enter the maximum length of an HTTP request in Kbytes. Larger requests will be rejec- ted.

 

Max HTTP mes- sage length

Enter the maximum length of an HTTP message in Kbytes. Larger messages will be rejected.

 

Configuring an external IP address for the IPv4 explicit web proxy

You can use the following command to set an external IP address (or pool) that will be used by the explicit web proxy policy.

config web-proxy explicit set status enable

set outgoing-ip <ip1> <ip2> … <ipN>

end

 

 

Configuring an external IP address for the IPv6 explicit web proxy

You can use the following command to set an external IP address (or pool) that will be used by the explicit web proxy policy.

config web-proxy explicit set status enable

set outgoing-ipv6 <ip1> <ip2> … <ipN>

end

 

Restricting the IP address of the IPv4 explicit web proxy

You can use the following command to restrict access to the explicit web proxy using only one IP address. The IP address that you specify must be the IP address of an interface that the explicit HTTP proxy is enabled on. You might want to use this option if the explicit FTP proxy is enabled on an interface with multiple IP addresses.

For example, to require uses to connect to the IP address 10.31.101.100 to connect to the explicit HTTP proxy:

config web-proxy explicit

set incoming-ip 10.31.101.100 end

 

Restricting the outgoing source IP address of the IPv4 explicit web proxy

You can use the following command to restrict the source address of outgoing web proxy packets to a single IP address. The IP address that you specify must be the IP address of an interface that the explicit HTTP proxy is enabled on. You might want to use this option if the explicit HTTP proxy is enabled on an interface with multiple IP addresses.

 

For example, to restrict the outgoing packet source address to 172.20.120.100:

config http-proxy explicit

set outgoing-ip 172.20.120.100 end

 

Restricting the IP address of the explicit IPv6 web proxy

You can use the following command to restrict access to the IPv6 explicit web proxy to use only one IP6 IP address. The IPv6 address that you specify must be the IPv6 address of an interface that the explicit HTTP proxy is enabled on. You might want to use this option if the explicit web proxy is enabled on an interface with multiple IPv6 addresses.

For example, to require uses to connect to the IPv6 address 2001:db8:0:2::30 to connect to the explicit IPv6 HTTP proxy:

config web-proxy explicit

set incoming-ipv6 2001:db8:0:2::30 end

 

Restricting the outgoing source IP address of the IPv6 explicit web proxy

You can use the following command to restrict the source address of outgoing web proxy packets to a single IPv6 address. The IP address that you specify must be the IPv6 address of an interface that the explicit HTTP proxy is enabled on. You might want to use this option if the explicit HTTP proxy is enabled on an interface with multiple IPv6 addresses.

 

For example, to restrict the outgoing packet source address to 2001:db8:0:2::50:

config http-proxy explicit

set outgoing-ipv6 2001:db8:0:2::50 end


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Unknown HTTP version

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Unknown HTTP version

You can select the action to take when the proxy server must handle an unknown HTTP version request or message. Set unknown HTTP version to Reject or Best Effort. Best Effort attempts to handle the HTTP traffic as best as it can. Reject treats known HTTP traffic as malformed and drops it. The Reject option is more secure.

 

Authentication realm

You can enter an authentication realm to identify the explicit web proxy. The realm can be any text string of up to 63 characters. If the realm includes spaces enclose it in quotes. When a user authenticates with the explicit web proxy the HTTP authentication dialog includes the realm so you can use the realm to identify the explicitly web proxy for your users.

 

Implementing Botnet features

The option scan-botnet-connections can be added to an explicit proxy policy.

 

CLI Syntax:

config firewall explicit-proxy-policy

edit <policy_id>

set scan-botnet-connections [disable|block|monitor]

end

 

where:

  • disable means do not scan connections to botnet servers.
  • block means block connections to botnet servers.
  • monitor means log connections to botnet servers.

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Proxy auto-config (PAC) configuration

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Proxy auto-config (PAC) configuration

A proxy auto-config (PAC) file defines how web browsers can choose a proxy server for receiving HTTP content. PAC files include the FindProxyForURL(url, host) JavaScript function that returns a string with one or more access method specifications. These specifications cause the web browser to use a particular proxy server or to connect directly.

To configure PAC for explicit web proxy users, you can use the port that PAC traffic from client web browsers use to connect to the explicit web proxy. explicit web proxy users must configure their web browser’s PAC proxy settings to use the PAC port.

 

PAC File Content

You can edit the default PAC file from the web-based manager or use the following command to upload a custom PAC file:

config web-proxy explicit

set pac-file-server-status enable set pac-file-data <pac_file_str>

end

Where <pac_file_str> is the contents of the PAC file. Enter the PAC file text in quotes. You can copy the contents of a PAC text file and paste the contents into the CLI using this option. Enter the command followed by two sets of quotes then place the cursor between the quotes and paste the file content.

The maximum PAC file size is 256 kbytes. If your FortiGate unit is operating with multiple VDOMs each VDOM has its own PAC file. The total amount of FortiGate memory available to store all of these PAC files 2 MBytes. If this limit is reached you will not be able to load any additional PAC files.

You can use any PAC file syntax that is supported by your users’s browsers. The FortiGate unit does not parse the PAC file.

To use PAC, users must add an automatic proxy configuration URL (or PAC URL) to their web browser proxy configuration. The default FortiGate PAC file URL is:

http://:/

For example, if the interface with the explicit web proxy has IP address 172.20.120.122, the PAC port is the same as the default HTTP explicit web proxy port (8080) and the PAC file name is proxy.pac the PAC file URL would be:

http://172.20.120.122:8080/proxy.pac

From the CLI you can use the following command to display the PAC file URLs:

get web-proxy explicit


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Explicit proxy firewall address types

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Explicit proxy firewall address types

Explicit proxy firewall address types improve granularity over header matching for explicit web proxy policies. You can enable this option using the Show in Address List button on the Address and Address Group New/Edit forms under Policy & Objects > Addresses.

 

The following address types are available:

  • URL Pattern – destination address
  • Host Regex Match – destination address
  • URL Category – destination address (URL filtering)
  • HTTP Method – source address
  • User Agent – source address
  • HTTP Header – source address
  • Advanced (Source) – source address (combines User Agent, HTTP Method, and HTTP Header)
  • Advanced (Destination) – destination address (combines Host Regex Match and URL Category)

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The FortiGate explicit web proxy

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The FortiGate explicit web proxy

You can use the FortiGate explicit web proxy to enable explicit proxying of IPv4 and IPv6 HTTP, and HTTPS traffic one or more FortiGate interfaces. The explicit web proxy also supports proxying FTP sessions from a web browser and proxy auto-config (PAC) to provide automatic proxy configurations for explicit web proxy users. From the CLI you can also configure the explicit web proxy to support SOCKS sessions from a web browser.

The explicit web and FTP proxies can be operating at the same time on the same or on different FortiGate interfaces.

If explicit web proxy options are not visible on the web-based manager, go to System > Feature Select and turn on Explicit Proxy.

In most cases you would configure the explicit web proxy for users on a network by enabling the explicit web proxy on the FortiGate interface connected to that network. Users on the network would configure their web browsers to use a proxy server for HTTP and HTTPS, FTP, or SOCKS and set the proxy server IP address to the IP address of the FortiGate interface connected to their network. Users could also enter the PAC URL into their web browser PAC configuration to automate their web proxy configuration using a PAC file stored on the FortiGate unit.

Enabling the explicit web proxy on an interface connected to the Internet is a security risk because anyone on the Internet who finds the proxy could use it to hide their source address.

If the FortiGate unit is operating in Transparent mode, users would configure their browsers to use a proxy server with the FortiGate management IP address.

If the FortiGate unit is operating with multiple VDOMs the explicit web proxy is configured for each VDOM. The web proxy receives web browser sessions to be proxied at FortiGate interfaces with the explicit web proxy enabled. The web proxy uses FortiGate routing to route sessions through the FortiGate unit to a destination interface. Before a session leaves the exiting interface, the explicit web proxy changes the source addresses of the session packets to the IP address of the exiting interface. When the FortiGate unit is operating in Transparent mode the explicit web proxy changes the source addresses to the management IP address. You can configure the explicit web proxy to keep the original client IP address. See Preventing the explicit web proxy from changing source addresses on page 2925.

 

For more information about explicit web proxy sessions, see Explicit web proxy sessions and user limits on page 2930.


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FortiClient WAN optimization over IPsec VPN configuration example

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FortiClient WAN optimization over IPsec VPN configuration example

This example shows how to add WAN optimization to a FortiClient IPsec VPN. The IPsec VPN tunnel allows remote FortiClient users to connect to the internal network behind the FortiGate unit.

 

Example FortiClient WAN optimization configuration

To configure the FortiGate unit

Because computers running FortiClient can have IP addresses that change often, it is usually not practical to add FortiClient peers to the FortiGate WAN optimization peer list. Instead, a FortiGate unit that accepts WAN optimization tunnel requests from FortiClient is usually configured to accept any peer. This example does this by adding a WAN optimization authentication group with Peer acceptance set to Accept Any Peer.

In addition this example includes a wanopt to internal policy to allow WAN optimization traffic reach the internal network. Finally passive WAN optimization is added to the ssl.root policy because WAN optimization is accepting traffic from the IPsec VPN tunnel.

1. Go to WAN Opt. & Cache > Authentication Groups and select Create New.

2. Configure the WAN optimization authentication group:

 

Name                                           auth-fc

Authentication Method            Certificate

Certificate                                   Fortinet_Firmware

Peer Acceptance                       Accept Any Peer

3. Select OK.

4. Go to WAN Opt. & Cache > Profiles and select Create New (select the + button).

5. Add a profile for FortiClient WAN optimization sessions:

Name                                           Fclient_Pro

Transparent Mode                    Select

Authentication Group              auth-fc

 

Category                                     Address

Address Name                           Internal-Server-Net

Type                                            IP Range

Subnet / IP Range                     192.168.10.0/24

Interface                                     internal

9. Enter the following CLI command to add an explicit proxy policy to accept WAN optimization tunnel connections.

configure firewall explicit-proxy-policy edit 0

set proxy wanopt

set dstintf internal set srcaddr all

set dstaddr all set action accept set schedule always set service ALL

next end

 

To set up IPsec VPN to support WAN optimization

1. Go to VPN > IPsec Wizard, enter a Name for the IPsec VPN and select Dialup – FortiClient (Windows, Mac OS, Android).

2. Follow the wizard steps to configure the VPN. No special WAN optimization settings are required.

3. Go to Policy & Objects > IPv4 Policy and edit the policy created by the wizard.

 

This policy has the IPsec VPN interface created by the wizard as the source interface.

4. Turn on WAN Optimization and configure the following settings:

 

Enable WAN Optimization       passive

Passive Option                          default

5. Select OK.

 

To configure FortiClient and start the WAN optimization SSL VPN connection

1. Open FortiClient, configure Advanced settings, and select Enable WAN optimization.

2. Add a new IPsec VPN connection.

 

Set the Server to the WAN1 IP address of the FortiGate unit (172.20.120.30 in this example).

No other settings are required for this example. You can add authentication in the form of a user name and password if required by the FortiGate unit.

3. Start the IPsec VPN tunnel.

 

You should be connected to the IPsec VPN tunnel and traffic in it should be optimized.


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