Authentication servers

FortiGate units support the use of external authentication servers. An authentication server can provide password checking for selected FortiGate users or it can be added as a member of a FortiGate user group.

If you are going to use authentication servers, you must configure the servers before you configure FortiGate users or user groups that require them.

This section includes the following topics:

l FortiAuthenticator servers l RADIUS servers l LDAP servers l TACACS+ servers l POP3 servers l SSO servers l RSA ACE (SecurID) servers

FortiAuthenticator servers

FortiAuthenticator is an Authentication, Authorization, and Accounting (AAA) server, that includes a RADIUS server, an LDAP server, and can replace the FSSO Collector Agent on a Windows AD network. Multiple FortiGate units can use a single FortiAuthenticator for FSSO, remote authentication, and FortiToken management.

For more information, see the FortiAuthenticator Administration Guide.

RADIUS servers

Remote Authentication and Dial-in User Service (RADIUS) is a broadly supported client-server protocol that provides centralized authentication, authorization, and accounting functions. RADIUS clients are built into gateways that allow access to networks such as Virtual Private Network servers, Network Access Servers (NAS), as well as network switches and firewalls that use authentication. FortiGate units fall into the last category.

RADIUS servers use UDP packets to communicate with the RADIUS clients on the network to authenticate users before allowing them access to the network, to authorize access to resources by appropriate users, and to account or bill for those resources that are used. RADIUS servers are currently defined by RFC 2865 (RADIUS) and RFC 2866 (Accounting), and listen on either UDP ports 1812 (authentication) and 1813 (accounting) or ports 1645 (authentication) and 1646 (accounting) requests. RADIUS servers exist for all major operating systems.

You must configure the RADIUS server to accept the FortiGate unit as a client. FortiGate units use the authentication and accounting functions of the RADIUS server.

FortiOS does not accept all characters from auto generated keys from MS Windows 2008. These keys are very long and as a result RADIUS authentication will not work. Maximum key length for MS Windows 2008 is 128 bytes. In older versions of FSAE, it was 40 bytes.

Microsoft RADIUS servers

Microsoft Windows Server 2000, 2003, and 2008 have RADIUS support built-in. Microsoft specific RADIUS features are defined in RFC 2548. The Microsoft RADIUS implementation can use Active Directory for user credentials.

For details on Microsoft RADIUS server configurations, refer to Microsoft documentation.

RADIUS user database

The RADIUS user database is commonly an SQL or LDAP database, but can also be any combination of:

l usernames and passwords defined in a configuration file l user account names and passwords configured on the computer where the RADIUS server is installed.

If users are members of multiple RADIUS groups, then the user group authentication timeout value does not apply.

RADIUS authentication with a FortiGate unit

To use RADIUS authentication with a FortiGate unit l configure one or more RADIUS servers on the FortiGate unit l assign users to a RADIUS server

When a configured user attempts to access the network, the FortiGate unit will forward the authentication request to the RADIUS server which will match the username and password remotely. Once authenticated the RADIUS server passes the authorization granted message to the FortiGate unit which grants the user permission to access the network.

The RADIUS server uses a “shared secret” key along with MD5 hashing to encrypt information passed between RADIUS servers and clients, including the FortiGate unit. Typically only user credentials are encrypted. Additional security can be configured through IPsec tunnels by placing the RADIUS server behind another VPN gateway.

RADIUS attribute value pairs

RADIUS packets include a set of attribute value pairs (AVP) to identify information about the user, their location and other information. The FortiGate unit sends the following RADIUS attributes.

FortiOS supported RADIUS attributes

RADIUS Attribute	Name	Description	AVP type
1	Acct-Session-ID	Unique number assigned to each start and stop record to make it easy to match them, and to eliminate duplicate records.	44
2	Username	Name of the user being authenticated	1
3	NAS-Identifier	Identifier or IP address of the Network Access Server (NAS) that is requesting authentication. In this case, the NAS is the FortiGate unit.	32
4	Framed-IP-Address	Address to be configured for the user.	8
5	Fortinet-VSA	See Vendor-specific attributes on page 26	26
6	Acct-Input-Octets	Number of octets received from the port over the course of this service being provided. Used to charge the user for the amount of traffic they used.	42
7	Acct-Output-Octets	Number of octets sent to the port while delivering this service. Used to charge the user for the amount of traffic they used.	43
8	NAS-IP-Address	IP address of the Network Access Server (NAS) that is requesting authentication. In this case, the NAS is the FortiGate unit.	4
9	Called-Station-Id	Used to send the telephone number the user called as part of the Access-Request packet.	30
10	Framed-IP-Address	IP address to be configured for the user, by sending the IP address of a user to the RADIUS server in the Access-Request packet.	8
11	Event-Timestamp	Records the time that the event occurred on the NAS. The timestamp is measured in seconds since January 1, 1970 00:00 UTC. Before the Event-Timestamp attribute can be sent in a packet, make sure that the correct time is set on the FortiGate.	55
12	Class	Used in accounting packets and requests for firewall, WiFi, and proxy authentication. The attribute is returned in Access-Access message and is added to all accounting packets.	25

The following table describes the supported authentication events and the RADIUS attributes that are sent in the RADIUS accounting message.

RADIUS attributes sent in RADIUS accounting message

	RADIUS Attributes
Authentication Method	1	2	3	4	5	6	7
Web	X	X	X		X
XAuth of IPsec (without DHCP)	X	X	X		X
XAuth of IPsec (with DHCP)	X	X	X	X	X
PPTP/L2TP (in PPP)	X	X	X	X	X	X	X
SSL-VPN	X	X	X	X	X

External captive portal POST message

In external RADIUS captive portal, the captive portal web page is a script that gathers the user’s logon credentials and sends it back to the FortiGate as a POST message. Session URL parameters are sent from the client in a POST messages, and in the redirect. These parameters are separated by & characters (see examples below):

POST message to redirect server:

http://<redirectserver>/index2.php/?login&post=http://192.168.200.1:1000/fgtau th&magic=02050f889bc21644&usermac=54:26:96:16:a2:45&apmac=00:09:0f:b9:f4:c0&ap ip=127.0.0.1&userip=192.168.200.2

POST message back to the FortiGate: http://FGT_IP_addr:1000/fgtauth

The magic text data, provided in the initial FortiGate request to the web server, contains the username, password parameters:

magic=00050c839182f095&username=<username>&password=<password>

Vendor-specific attributes

Vendor specific attributes (VSA) are the method RADIUS servers and client companies use to extend the basic functionality of RADIUS. Some major vendors, such as Microsoft, have published their VSAs, however many do not.

In order to support vendor-specific attributes (VSA), the RADIUS server requires a dictionary to define which VSAs to support. This dictionary is typically supplied by the client or server vendor.

The Fortinet RADIUS vendor ID is 12356.

The FortiGate unit RADIUS VSA dictionary is supplied by Fortinet and is available through the Fortinet Knowledge Base (http://kb.forticare.com) or through Technical Support. Fortinet’s dictionary for FortiOS 4.0 and up is configured this way:

##

Fortinet’s VSA’s

#

VENDOR fortinet 12356

BEGIN-VENDOR fortinet

ATTRIBUTE Fortinet-Group-Name   1   string

ATTRIBUTE Fortinet-Client-IP-Address   2   ipaddr

ATTRIBUTE Fortinet-Vdom-Name   3   string

ATTRIBUTE Fortinet-Client-IPv6-Address   4   octets

ATTRIBUTE Fortinet-Interface-Name   5   string

ATTRIBUTE Fortinet-Access-Profile   6   string

#

# Integer Translations

#

END-VENDOR Fortinet

Note that using the Fortinet-Vdom-Name, users can be tied to a specific VDOM on the FortiGate unit. See the documentation provided with your RADIUS server for configuration details.

RADIUS CoA support

As of FortiOS 5.4, RADIUS Change of Authorization (CoA) settings can be configured via the CLI. CoA is a common feature in user authentication that provides the ability to change authentication attributes for sessions even after they have authenticated.

User, user group, and captive portal authentication supports RADIUS CoA, when the back end authentication server is RADIUS. The main use case of this feature is with external captive portal, where it can be used to disconnect hotspot users when their time, credit, or bandwidth has been used up.

The commands below control CoA settings.

1. Set the name of the FortiAP connected to the FortiGate as a location identifier.

config system global set alias <name>

2. Set URL of external authentication logout server.

config vdom edit root config wireless-controller vap edit <example> set security captive-portal set external-logout

3. Set URL of external authentication logout server config vdom edit root config system interface edit <example> set security captive-portal set security-external-logout
4. Set class name(s) included in an Access-Accept message.

config vdom edit root config user radius edit accounting set class <“A1=aaa” “B2=bbb” “C3=ccc”>

Role-based access control

In role-based access control (RBAC), network administrators and users have varying levels of access to network resources based on their role, and that role’s requirement for access specific resources. For example, a junior accountant does not require access to the sales presentations, or network user account information.

There are three main parts to RBAC: role assignment, role authorization, and transaction authorization. Role assignment is accomplished when someone in an organization is assigned a specific role by a manager or HR. Role authorization is accomplished when a network administrator creates that user’s RADIUS account and assigns them to the required groups for that role. Transaction authorization occurs when that user logs on and authenticates before performing a task.

RBAC is enforced when FortiOS network users are remotely authenticated via a RADIUS server. For users to authenticate, a security policy must be matched. That policy only matches a specific group of users. If VDOMs are enabled, the matched group will be limited to a specific VDOM. Using this method network administrators can separate users into groups that match resources, protocols, or VDOMs. It is even possible to limit users to specific FortiGate units if the RADIUS servers serve multiple FortiOS units.

For more information on security policies, see Authentication in security policies on page 80.

RADIUS password encoding

Certain RADIUS servers use ISO-8859-1 password encoding instead of others such as UTF-8. In these instances, the server will fail to authenticate the user, if the user’s password is using UTF-8.

CLI syntax

config user radius edit <example> set password-encoding <auto | ISO-8859-1>

end

This option will be skipped if the auth-type is neither auto nor pap.

RADIUS accounting start message options

Administrators can now choose between sending accounting start messages to all configured accounting servers, or just the one server that was previously connected.

Syntax

config user radius edit <name> set acct-interim-interval <seconds> set acct-all-servers {enable | disable}

next end

Configuring the FortiGate unit to use a RADIUS server

The information you need to configure the FortiGate unit to use a RADIUS server includes l the RADIUS server’s domain name or IP address l the RADIUS server’s shared secret key.

You can optionally specify the NAS IP or Called Station ID. When configuring the FortiGate to use a RADIUS server, the FortiGate is a Network Access Server (NAS). If the FortiGate interface has multiple IP addresses, or you want the RADIUS requests to come from a different address you can specify it here. Called Station ID applies to carrier networks. However, if the NAS IP is not included in the RADIUS configuration, the IP of the FortiGate unit interface that communicates with the RADIUS server is used instead.

A maximum of 10 remote RADIUS servers can be configured on the FortiGate unit. One or more servers must be configured on FortiGate before remote users can be configured. To configure remote users, see Local and remote users on page 50.

On the FortiGate unit, the default port for RADIUS traffic is 1812. Some RADIUS servers use port 1645. If this is the case with your server, you can either:

• Re-configure the RADIUS server to use port 1812. See your RADIUS server documentation for more information on this procedure.

or

• Change the FortiGate unit default RADIUS port to 1645 using the CLI:

config system global set radius-port 1645

end

One wildcard admin account can be added to the FortiGate unit when using RADIUS authentication. This uses the wildcard character to allow multiple admin accounts on RADIUS to use a single account on the FortiGate unit. See Example — wildcard admin accounts – CLI on page 36.

To configure the FortiGate unit for RADIUS authentication – web-based manager:

1. Go to User & Device > RADIUS Servers and select Create New.
2. Enter the following information and select OK.

Name	A name to identify the RADIUS server on the FortiGate unit.
Authentication method	If you know the RADIUS server uses a specific authentication protocol, select Specify and select it from the list. Otherwise select Default. The Default option will usually work.
NAS IP	Enter the IP address to be used as the NAS-IP-Address attribute in RADIUS access requests.
Include in every user group	When enabled this RADIUS server will automatically be included in all user groups. This is useful if all users will be authenticating with the remote RADIUS server.
Primary Server	IP/Name: Enter the domain name (such as fgt.exmaple.com) or the IP address of the RADIUS server. Secret: Enter the server secret key, such as radiusSecret. This can be a maximum of 16 characters long. This must match the secret on the RADIUS primary server. Test Connectivity: Test the validity of the IP/Name. Test User Connectivity: Test the validity of the Secret.
Secondary Server	IP/Name: Optionally enter the domain name (such as fgt.exmaple.com) or the IP address of the secondary RADIUS server. Secret: Optionally, enter the secondary server secret key, such as radiusSecret2. This can be a maximum of 16 characters long. This must match the secret on the RADIUS secondary server. Test Connectivity: Test the validity of the IP/Name. Test User Connectivity: Test the validity of the Secret.

3. Select OK.

To configure the FortiGate unit for RADIUS authentication – CLI example:

config user radius edit ourRADIUS set auth-type auto set server 10.11.102.100 set secret radiusSecret

end

For more information about RADIUS server options, refer to the FortiGate CLI Reference.

Troubleshooting RADIUS

To test the connection to the RADIUS server use the following command: diagnose test authserver radius-direct <server_name or IP> <port number> <secret>

For the port number, enter -1 to use the default port. Otherwise enter the port number to check.

Test results show RADIUS server reachability, NAS client rejection, and invalid User/Password. Test also shows RADIUS Attributes returned from the RADIUS server.

 

LDAP servers

Lightweight Directory Access Protocol (LDAP) is an Internet protocol used to maintain authentication data that may include departments, people, groups of people, passwords, email addresses, and printers. LDAP consists of a data-representation scheme, a set of defined operations, and a request/response network.

The scale of LDAP servers range from big public servers such as BigFoot and Infospace, to large organizational servers at universities and corporations, to small LDAP servers for workgroups that may be using OpenLDAP.

This document focuses on the institutional and workgroup applications of LDAP.

This section includes:

l Components and topology l LDAP directory organization l Configuring the FortiGate unit to use an LDAP server l Example — wildcard admin accounts – CLI l Example of LDAP to allow dial-in through member-attribute – CLI l Troubleshooting LDAP

Components and topology

LDAP organization starts with directories. A directory is a set of objects with similar attributes organized in a logical and hierarchical way. Generally, an LDAP directory tree reflects geographic and organizational boundaries, with the Domain name system (DNS) names to structure the top level of the hierarchy. The common name identifier for most LDAP servers is cn, however some servers use other common name identifiers such as uid.

When LDAP is configured and a user is required to authenticate the general steps are:

1. The FortiGate unit contacts the LDAP server for authentication.
2. To authenticate with the FortiGate unit, the user enters a username and password.
3. The FortiGate unit sends this username and password to the LDAP server.
4. If the LDAP server can authenticate the user, the user is successfully authenticated with the FortiGate unit.
5. If the LDAP server cannot authenticate the user, the connection is refused by the FortiGate unit.

Binding

Binding is the step where the LDAP server authenticates the user. If the user is successfully authenticated, binding allows the user access to the LDAP server based on that user’s permissions.

The FortiGate unit can be configured to use one of three types of binding:

l anonymous – bind using anonymous user search l regular – bind using username/password and then search l simple – bind using a simple password authentication without a search

You can use simple authentication if the user records all fall under one domain name (dn). If the users are under more than one dn, use the anonymous or regular type, which can search the entire LDAP database for the required username.

If your LDAP server requires authentication to perform searches, use the regular type and provide values for username and password.

Supported versions

The FortiGate unit supports LDAP protocol functionality defined in RFC 2251: Lightweight Directory Access Protocol v3, for looking up and validating user names and passwords. FortiGate LDAP supports all LDAP servers compliant with LDAP v3, including FortiAuthenticator. In addition, FortiGate LDAP supports LDAP over SSL/TLS, which can be configured only in the CLI.

FortiGate LDAP does not support proprietary functionality, such as notification of password expiration, which is available from some LDAP servers. FortiGate LDAP does not supply information to the user about why authentication failed.

LDAP user authentication is supported for PPTP, L2TP, IPsec VPN, and firewall authentication.

However, with PPTP, L2TP, and IPsec VPN, PAP (Packet Authentication Protocol) is supported, while CHAP (Challenge Handshake Authentication Protocol) is not.

LDAP directory organization

To configure your FortiGate unit to work with an LDAP server, you need to understand the organization of the information on the server.

The top of the hierarchy is the organization itself. Usually this is defined as Domain Component (DC), a DNS domain. If the name contains a dot, such as example.com, it is written as two parts separated by a comma: dc=example,dc=com.

In this example, Common Name (CN) identifiers reside at the Organization Unit (OU) level, just below DC. The Distinguished Name (DN) is ou=People,dc=example,dc=com.

LDAP object hierarchy

In addition to the DN, the FortiGate unit needs an identifier for the individual person. Although the FortiGate unit GUI calls this the Common Name (CN), the identifier you use is not necessarily CN. On some servers, CN is the full name of a person. It might be more convenient to use the same identifier used on the local computer network. In this example, User ID (UID) is used.

Locating your identifier in the hierarchy

You need to determine the levels of the hierarchy from the top to the level that contain the identifier you want to use. This defines the DN that the FortiGate unit uses to search the LDAP database. Frequently used distinguished name elements include:

• uid (user identification) l pw (password) l cn (common name)
• ou (organizational unit) l o (organization) l c (country)

One way to test this is with a text-based LDAP client program. For example, OpenLDAP includes a client, ldapsearch, that you can use for this purpose.

Enter the following at the command line: ldapsearch -x ‘(objectclass=*)’

The output is lengthy, but the information you need is in the first few lines:

version: 2

#

# filter: (objectclass=*) # requesting: ALL

dn: dc=example,dc=com dc: example objectClass: top objectClass: domain

dn: ou=People,dc=example,dc=com

ou: People objectClass: top objectClass: organizationalUnit … dn: uid=tbrown,ou=People,dc=example,dc=com

uid: tbrown cn: Tom Brown

In the output above, you can see tbrown (uid) and Tom Brown(cn). Also note the dn is ou=People, dc=example, dc=com.

Configuring the FortiGate unit to use an LDAP server

After you determine the common name and distinguished name identifiers and the domain name or IP address of the LDAP server, you can configure the server on the FortiGate unit. The maximum number of remote LDAP servers that can be configured is 10.

One or more servers must be configured on FortiGate before remote users can be configured.

To configure the FortiGate unit for LDAP authentication – web-based manager:

1. Go to User & Device > LDAP Servers and select Create New.
2. Enter a Name for the LDAP server.
3. In Server Name/IP enter the server’s FQDN or IP address.
4. If necessary, change the Server Port The default is port 389.
5. Enter the Common Name Identifier (20 characters maximum).

cn is the default, and is used by most LDAP servers.

6. In the Distinguished Name field, enter the base distinguished name for the server using the correct X.500 or LDAP format.

The FortiGate unit passes this distinguished name unchanged to the server. The maximum number of characters is 512.

If you don’t know the distinguished name, leave the field blank and select the Query icon to the right of the field. See Using the query icon on page 35.

7. In the Distinguished Name field, enter the base distinguished name for the server using the correct X.500 or LDAP format.

The FortiGate unit passes this distinguished name unchanged to the server. The maximum number of characters is 512.

If you don’t know the distinguished name, leave the field blank and select the Query icon to the right of the field.

See Using the query icon on page 35.

8. In Bind Type, select Regular.
9. In User DN, enter the LDAP administrator’s distinguished name.
10. In Password, enter the LDAP administrator’s password.
11. Select OK.

To verify your Distinguished Name field is correct, you can select the Test button. If your DN field entry is valid, you will see the part of the LDAP database it defines. If your DN field entry is not valid, it will display an error message and return no information.

For detailed information about configuration options for LDAP servers, see the Online Help on your FortiGate unit or the FortiGate CLI Reference.

To configure the FortiGate unit for LDAP authentication – CLI example:

config user ldap edit ourLDAPsrv set server 10.11.101.160

set cnid cn

set dn cn=users,dc=office,dc=example,dc=com

set type regular

set username cn=administrator,cn=users,dc=office,dc=example,dc=com set password w5AiGVMLkgyPQ set password-expiry-warning enable set password-renewal enable end

password-expiry-warning and password-renewal

In SSLVPN, when an LDAP user is connecting to the LDAP server it is possible for them to receive any pending password expiry or renewal warnings. When the password renewal or expiry warning exists, SSLVPN users will see a prompt allowing them to change their password.

password-expiry-warning allows FortiOS to detect from the OpenLDAP server when a password is expiring or has expired using server controls or error codes. Please note that this is currently not supported for Windows AD LDAP.

password-renewal allows FortiOS to perform the online LDAP password renewal operations the LDAP server expects.

On an OpenLDAP server, when a user attempts to logon with an expired password they are allowed to logon but only to change their password.

When changing passwords on a Windows AD system, the connection must be SSL-protected.

UPN processing method and filter name

The following CLI commands available under config user ldap allow you to keep or strip the domain string of userPrincipalName (UPN) in the token as well as the search name for this kind of UPN.

Principle name peer user mode was only supported with Windows AD, and fnbamd has a hard coded UserAccountControl when doing LDAP authentication. UserAccountControl is a Windows AD specific attribute which doesn’t exist in FortiAuthenticator or OpenLDAP.

To make LDAP query more flexible with different LDAP server versions, account-key-filter has been introduced to replace account-key-name. Enter the UPN attribute as the filter.

CLI syntax:

config user ldap set account-key-processing set account-key-filter

end

Using the query icon

The LDAP Distinguished Name Query list displays the LDAP directory tree for the LDAP server connected to the FortiGate unit. This helps you to determine the appropriate entry for the DN field. To see the distinguished name associated with the Common Name identifier, select the Expand icon next to the CN identifier. Select the DN from the list. The DN you select is displayed in the Distinguished Name field. Select OK and the Distinguished Name you selected will be saved in the Distinguished Name field of the LDAP Server configuration.

To see the users within the LDAP Server user group for the selected Distinguished Name, expand the Distinguished Name in the LDAP Distinguished Name Query tree.

LDAP server Distinguished Name Query tree

Non-blocking LDAP authentication

To support non-blocking LDAP authentication, fnbamd will create its own event-driven connection with LDAP servers over LDAP/LDAPS/STARTTLS, make it non-blocking, do CRL checking if necessary, and compose all LDAP requests using liblber (including bind, unbind, search, password renewal, password query, send request and receive response, and parse response). The whole process is done in one connection.

This doesn’t change any openLDAP implementation but moves some data structure definitions and API definitions from some internal header files to public header files.

Example — wildcard admin accounts – CLI

A wildcard admin account is an administrator account with the wildcard option enabled. This option allows multiple different remote administration accounts to match one local administration account, avoiding the need to set up individual admin accounts on the FortiGate unit. Instead multiple LDAP admin accounts will all be able to use one FortiGate admin account.

The initial benefit of wildcard admin accounts is fast configuration of the FortiGate unit’s administration account to work with your LDAP network. The many to one ratio saves on effort, and potential errors.

The ongoing benefit is that as long as the users on the LDAP system belong to that group, and the test admin user settings don’t change on the FortiGate unit, no other work is required. This point is important as it can help avoid system updates or changes that would otherwise require changes to the LDAP administrator account configuration. Even if a user is added to or removed from the LDAP group, no changes are required on the FortiGate unit.

Two potential issues with wildcard admin accounts are that multiple users may be logged on to the same account at the same time. This becomes an issue if they are changing the same information at the same time. The other potential issue is that security is reduced because multiple people have login access for the same account. If each user was assigned their own account, a hijacking of one account would not affect the other users.

Note that wildcard admin configuration also applies to RADIUS. When configuring for RADIUS, configure the RADIUS server, and RADIUS user group instead of LDAP. When using web-based management, wildcard admin is the only type of remote administrator account that does not require you to enter a password on account creation. That password is normally used when the remote authentication server is unavailable during authentication.

In this example, default values are used where possible. If a specific value is not mentioned, it is set to its default value.

Configuring the LDAP server

The important parts of this configuration are the username and group lines. The username is the domain administrator account. The group binding allows only the group with the name GRP to access.

To configure LDAP server – CLI:

config user ldap edit “ldap_server” set server “192.168.201.3” set cnid “sAMAccountName” set dn “DC=example,DC=com,DC=au”

set type regular

set username “CN=Administrator,CN=Users,DC=example,DC=COM” set password *

set group-member-check group-object set group-object-filter (&

(objectcategory=group)member=”CN=GRP,OU=training,DC=example,DC=COM”)) next

end

To configure the user group and add the LDAP server – CLI:

config user group edit “ldap_grp” set member “ldap” config match

edit 1 set server-name “ldap_server”

set group-name “CN=GRP,OU=training,DC=example,DC=COM”

next

end

next end

Configuring the admin account

The wildcard part of this example is only available in the CLI for admin configuration. When enabled, this allows all LDAP group members to login to the FortiGate unit without the need to create a separate admin account for each user. In effect the members of that group will each be able to login as “test”.

To configure the admin account – CLI:

config system admin edit “test” set remote-auth enable set accprofile “super_admin” set wildcard enable set remote-group “ldap_grp”

next

end

For troubleshooting, test that the admin account is operational, and see Troubleshooting LDAP on page 39.

Example of LDAP to allow dial-in through member-attribute – CLI

In this example, users defined in MicroSoft Windows Active Directory (AD) are allowed to setup a VPN connection simply based on an attribute that is set to TRUE, instead of based on being part of a specific group.

In AD, the “Allow Dial-In” property is activated in the user properties, and this sets the msNPAllowDialin attribute to “TRUE”.

This same procedure can be used for other member attributes, as your system requires.

Configuring LDAP member-attribute settings

To accomplish this with a FortiGate unit, the member attribute must be set. Setting member attributes can only be accomplished through the CLI using the member-attr keyword – the option is not available through the webbased manager.

Before configuring the FortiGate unit, the AD server must be configured and have the msNPAllowDialin attribute set to “TRUE” for the users in question. If not, those users will not be able to properly authenticate.

The dn used here is as an example only. On your network use your own domain name.

To configure user LDAP member-attribute settings – CLI:

config user ldap edit “ldap_server” set server “192.168.201.3” set cnid “sAMAccountName” set dn “DC=fortinet,DC=com,DC=au” set type regular

set username “fortigate@example.com” set password ****** set member-attr “msNPAllowDialin”

next end

Configuring LDAP group settings

A user group that will use LDAP must be configured. This example adds the member ldap to the group which is the LDAP server name that was configured earlier.

To configure LDAP group settings – CLI:

config user group edit “ldap_grp” set member “ldap” config match edit 1 set server-name “ldap” set group-name “TRUE”

next

end

end

Once these settings are in place, users can authenticate.

Types of authentication

FortiOS supports two different types of authentication based on your situation and needs: security policy authentication and Virtual Private Network (VPN) authentication.

Security policy authentication is easily applied to all users logging on to a network, or network service. For example if a group of users on your network such as the accounting department who have access to sensitive data need to access the Internet, it is a good idea to make sure the user is a valid user and not someone trying to send company secrets to the Internet. Security policy authentication can be applied to as many or as few users as needed, and it supports a number of authentication protocols to easily fit with your existing network.

VPN authentication enables secure communication with hosts located outside the company network, making them part of the company network while the VPN tunnel is operating. Authentication applies to the devices at both ends of the VPN and optionally VPN users can be authenticated as well.

Security policy authentication

Security policies enable traffic to flow between networks. Optionally, the policy can allow access only to specific originating addresses, device types, users or user groups. Where access is controlled by user or user group, users must authenticate by entering valid username and password credentials.

The user’s authentication expires if the connection is idle for too long, five minutes by default but that can be customized.

Security policies are the mechanism for FSSO, NTLM, certificate based, and RADIUS SSO authentication.

FSSO

Fortinet Single Sign on (FSSO) provides seamless authentication support for Microsoft Windows Active Directory (AD) and Novell eDirectory users in a FortiGate environment.

On a Microsoft Windows or Novell network, users authenticate with the Active Directory or Novell eDirectory at login. FSSO provides authentication information to the FortiGate unit so that users automatically get access to permitted resources. See Introduction to agent-based FSSO on page 147.

NTLM

The NT LAN Manager (NTLM) protocol is used when the MS Windows Active Directory (AD) domain controller can not be contacted. NTLM is a browser-based method of authentication.

The FSSO software is installed on each AD server and the FortiGate unit is configured to communicate with each

FSSO client. When a user successfully logs into their Windows PC (and is authenticated by the AD Server), the

FSSO client communicates the user’s name, IP address, and group login information to the FortiGate unit. The FortiGate unit sets up a temporary access policy for the user, so when they attempt access through the firewall they do not need to re-authenticate. This model works well in environments where the FSSO client can be installed on all AD servers.

In system configurations where it is not possible to install FSSO clients on all AD servers, the FortiGate unit must be able to query the AD servers to find out if a user has been properly authenticated. This is achieved using the NTLM messaging features of Active Directory and Internet Explorer.

Even when NTLM authentication is used, the user is not asked again for their username and password. Internet Explorer stores the user’s credentials and the FortiGate unit uses NTLM messaging to validate them in the Windows AD environment.

Note that if the authentication reaches the timeout period, the NTLM message exchange restarts. For more information on NTLM, see NTLM authentication on page 86 and FSSO NTLM authentication support on page 153.

Certificates

RADIUS SSO

RADIUS Single Sign-On (RSSO) is a remote authentication method that does not require any local users to be configured, and relies on RADIUS Start records to provide the FortiGate unit with authentication information. That information identifies the user and user group, which is then matched using a security policy. See SSO using RADIUS accounting records on page 192.

FortiGuard web filter override authentication

Optionally, users can be allowed the privilege of overriding FortiGuard Web Filtering to view blocked web sites. Depending on the override settings, the override can apply to the user who requested it, the entire user group to which the user belongs, or all users who share the same web filter profile. As with other FortiGate features, access to FortiGuard overrides is controlled through user groups. Firewall and Directory Services user groups are eligible for the override privilege. For more information about web filtering and overrides, see the UTM chapter of this FortiOS Handbook.

VPN authentication

Authentication involves authenticating the user. In IPsec VPNs authenticating the user is optional, but authentication of the peer device is required. This section includes:

l Authenticating IPsec VPN peers (devices) l Authenticating IPsec VPN users l Authenticating SSL VPN users l Authenticating PPTP and L2TP VPN users

Authenticating IPsec VPN peers (devices)

A VPN tunnel has one end on a local trusted network, and the other end is at a remote location. The remote peer (device) must be authenticated to be able to trust the VPN tunnel. Without that authentication, it is possible for a malicious hacker to masquerade as a valid VPN tunnel device and gain access to the trusted local network.

The three ways to authenticate VPN peers are with a pre-shared key, RSA X.509 certificate, or a specific peer ID value.

The simplest way for IPsec VPN peers to authenticate each other is through the use of a pre-shared key, also called a shared secret. The pre-shared key is a text string used to encrypt the data exchanges that establish the VPN tunnel. The pre-shared key must be six or more characters. The VPN tunnel cannot be established if the two peers do not use the same key. The disadvantage of pre-shared key authentication is that it can be difficult to securely distribute and update the pre-shared keys.

RSA X.509 certificates are a better way for VPN peers to authenticate each other. Each peer offers a certificate signed by a Certificate Authority (CA) which the other peer can validate with the appropriate CA root certificate. For more information about certificates, see Certificate-based authentication on page 110.

You can supplement either pre-shared key or certificate authentication by requiring the other peer to provide a specific peer ID value. The peer ID is a text string configured on the peer device. On a FortiGate peer or FortiClient Endpoint Security peer, the peer ID provided to the remote peer is called the Local ID.

Authenticating IPsec VPN users

An IPsec VPN can be configured to accept connections from multiple dynamically addressed peers. You would do this to enable employees to connect to the corporate network while traveling or from home. On a FortiGate unit, you create this configuration by setting the Remote Gateway to Dialup User.

It is possible to have an IPsec VPN in which remote peer devices authenticate using a common pre-shared key or a certificate, but there is no attempt to identify the user at the remote peer. To add user authentication, you can do one of the following:

l require a unique pre-shared key for each peer l require a unique peer ID for each peer l require a unique peer certificate for each peer l require additional user authentication (XAuth)

The peer ID is a text string configured on the peer device. On a FortiGate peer or FortiClient Endpoint Security peer, the peer ID provided to the remote peer is called the Local ID.

Authenticating SSL VPN users

SSL VPN users can be l user accounts with passwords stored on the FortiGate unit l user accounts authenticated by an external RADIUS, LDAP or TACACS+ server l PKI users authenticated by certificate

You need to create a user group for your SSL VPN. Simply create a firewall user group, enable SSL VPN access for the group, and select the web portal the users will access.

SSL VPN access requires an SSL VPN security policy that permits access to members of your user group.

Authenticating PPTP and L2TP VPN users

PPTP and L2TP are older VPN tunneling protocols that do not provide authentication themselves. FortiGate units restrict PPTP and L2TP access to users who belong to one specified user group. Users authenticate themselves to the FortiGate unit by username/password. You can configure PPTP and L2TP VPNs only in the CLI. Before you configure the VPN, create a firewall user group and add to it the users who are permitted to use the VPN. Users are authenticated when they attempt to connect to the VPN. For more information about configuring PPTP or L2TP VPNs, see the FortiGate CLI Reference.

Single sign-on authentication for users

Single sign-on (SSO)means that users logged on to a computer network are authenticated for access to network resources through the FortiGate unit without having to enter their username and password again. FortiGate units directly provide SSO capability for:

l Microsoft Windows networks using either Active Directory or NTLM authentication l Novell networks, using eDirectory

In combination with a FortiAuthenticator unit, the FortiGate unit can provide SSO capability that integrates multiple external network authentication systems such as Windows Active Directory, Novell e-Directory, RADIUS and LDAP. The FortiAuthenticator unit gathers user logon information from all of these sources and sends it to the FortiGate unit.

Through the SSO feature, the FortiGate unit knows the username, IP address, and external user groups to which the user belongs. When the user tries to access network resources, the FortiGate unit selects the appropriate security policy for the destination. If the user belongs to one of the permitted user groups, the connection is allowed.

User’s view of authentication

From the user’s point of view, they see a request for authentication when they try to access a protected resource, such as an FTP repository of intellectual property or simply access a website on the Internet. The way the request is presented to the user depends on the method of access to that resource.

VPN authentication usually controls remote access to a private network.

Web-based user authentication

Security policies usually control browsing access to an external network that provides connection to the Internet. In this case, the FortiGate unit requests authentication through the web browser.

The user types a username and password and then selects Continue or Login. If the credentials are incorrect, the authentication screen is redisplayed with blank fields so that the user can try again. When the user enters valid credentials, access is granted to the required resource. In some cases, if a user tries to authenticate several times without success, a message appears, such as: “Too many bad login attempts. Please try again in a few minutes.” This indicates the user is locked out for a period of time. This prevents automated brute force password hacking attempts. The administrator can customize these settings if required.

After a defined period of user inactivity (the authentication timeout, defined by the FortiGate administrator), the user’s access expires. The default is 5 minutes. To access the resource, the user will have to authenticate again.

VPN client-based authentication

A VPN provides remote clients with access to a private network for a variety of services that include web browsing, email, and file sharing. A client program such as FortiClient negotiates the connection to the VPN and manages the user authentication challenge from the FortiGate unit.

FortiClient can store the username and password for a VPN as part of the configuration for the VPN connection and pass them to the FortiGate unit as needed. Or, FortiClient can request the username and password from the user when the FortiGate unit requests them.

Social ID data from FortiClient is recorded so that if an email or phone number is changed on FortiClient, the new values are updated on the FortiGate.

The data is sent in KeepAlive messages in the following format:

USR_NAME|<full name for the service account>|USR_

EMAIL|<email for the service account>|SERVICE|<os|custom|linkedin|google|salesforce>|

SSL VPN is a form of VPN that can be used with a standard Web browser. There are two modes of SSL VPN operation (supported in NAT/Route mode only):

l web-only mode, for remote clients equipped with a web-browser only l tunnel mode, for remote computers that run a variety of client and server applications.

After a defined period of user inactivity on the VPN connection (the idle timeout, defined by the FortiGate administrator), the user’s access expires. The default is 30 minutes. To access the resource, the user will have to authenticate again.

FortiGate administrator’s view of authentication

Authentication is based on user groups. The FortiGate administrator configures authentication for security policies and VPN tunnels by specifying the user groups whose members can use the resource. Some planning is required to determine how many different user groups need to be created. Individual user accounts can belong to multiple groups, making allocation of user privileges very flexible.

A member of a user group can be:

• a user whose username and password are stored on the FortiGate unit l a user whose name is stored on the FortiGate unit and whose password is stored on a remote or external authentication server
• a remote or external authentication server with a database that contains the username and password of each person who is permitted access

The general process of setting up authentication is as follows:

1. If remote or external authentication is needed, configure the required servers.

General authentication settings

2. Configure local and peer (PKI) user identities. For each local user, you can choose whether the FortiGate unit or a remote authentication server verifies the password. Peer members can be included in user groups for use in security policies.
3. Create user groups.
4. Add local/peer user members to each user group as appropriate. You can also add an authentication server to a user group. In this case, all users in the server’s database can authenticate. You can only configure peer user groups through the CLI.
5. Configure security policies and VPN tunnels that require authenticated access.

For authentication troubleshooting, see the specific chapter for the topic or for general issues see Troubleshooting on page 219.

General authentication settings

Go to User & Device > Authentication Settings to configure authentication timeout, protocol support, and authentication certificates.

When user authentication is enabled within a security policy, the authentication challenge is normally issued for any of the four protocols (depending on the connection protocol):

• HTTP (can also be set to redirect to HTTPS) l HTTPS l FTP
• Telnet

The selections made in the Protocol Support list of Authentication Settings control which protocols support the authentication challenge. Users must connect with a supported protocol first so they can subsequently connect with other protocols. If HTTPS is selected as a method of protocol support, it allows the user to authenticate with a customized Local certificate.

When you enable user authentication within a security policy, the security policy user will be challenged to authenticate. For user ID and password authentication, users must provide their user names and passwords. For certificate authentication (HTTPS or HTTP redirected to HTTPS only), you can install customized certificates on the unit and the users can also have customized certificates installed on their browsers. Otherwise, users will see a warning message and have to accept a default Fortinet certificate.

Authentication Timeout	Enter a length of time in minutes, from 1 to 4320 (72 hours). Authentication timeout controls how long an authenticated firewall connection can be idle before the user must authenticate again. The default value is 5.
Protocol Support	Select the protocols to challenge during firewall user authentication.
Certificate	If using HTTPS protocol support, select the local certificate to use for authentication. Available only if HTTPS protocol support is selected.
Apply	Select to apply the selections for user authentication settings.

 

Authentication binds to MAC address

In previous FortiOS versions, firewall authentication was source IP based, thus there was no action in response to a MAC address change. This was a security flaw that allowed an unauthenticated user to access restricted resources, especially in a WiFi environment where the IP and MAC binding changed frequently.

MAC addresses can now be bound with the user identity so that the MAC address is matched while matching an auth logon.

Two-factor authentication

A user can be required to provide both something they know (their username and password combination) and something they have (certificate or a random token code). Certificates are installed on the user’s computer.

Two-factor authentication is available for PKI users.

Another type of two-factor authentication is to use a randomly generated token (multi-digit number) along with the username and password combination. One method is a FortiToken — a one-time password (OTP) generator that generates a unique code every 60 seconds. Others use email or SMS text messaging to deliver the random token code to the user or administrator.

When one of these methods is configured, the user enters this code at login after the username and password have been verified. The FortiGate unit verifies the token code after as well as the password and username.

Certificate-based authentication

An RSA X.509 server certificate is a small file issued by a certificate authority (CA) that is installed on a computer or FortiGate unit to authenticate itself to other devices on the network. When one party on a network presents the certificate as authentication, the other party can validate that the certificate was issued by the CA. The identification is therefore as trustworthy as the CA that issued the certificate.

To protect against compromised or misused certificates, CAs can revoke any certificate by adding it to a certificate revocation list (CRL). Certificate status can also be checked online using the Online Certificate Status Protocol (OCSP).

RSA X.509 certificates are based on public-key cryptography, in which there are two keys: the private key and the public key. Data encrypted with the private key can be decrypted only with the public key, and the other way round. As the names suggest, the private key is never revealed to anyone and the public key can be freely distributed. Encryption with the recipient’s public key creates a message that only the intended recipient can read. Encryption with the sender’s private key creates a message whose authenticity is proven because it can be decrypted only with the sender’s public key.

Server certificates contain a signature string encrypted with the CA’s private key. The CA’s public key is contained in a CA root certificate. If the signature string can be decrypted with the CA’s public key, the certificate is genuine. Certificate authorities

A CA can be:

l an organization, such as VeriSign Inc., that provides certificate services l a software application, such as Microsoft Certificate Services or OpenSSH

For a company web portal or customer-facing SSL VPN, a third-party certificate service has some advantages. The CA certificates are already included in popular web browsers and customers trust the third-party. On the other hand, third-party services have a cost.

For administrators and for employee VPN users, the local CA based on a software application provides the required security at low cost. You can generate and distribute certificates as needed. If an employee leaves the organization, you can simply revoke their certificate.

Certificates for users

FortiGate unit administrators and SSL VPN users can install certificates in their web browsers to authenticate themselves. If the FortiGate unit uses a CA-issued certificate to authenticate itself to the clients, the browser will also need the appropriate CA certificate.

FortiGate IPsec VPN users can install server and CA certificates according to the instructions for their IPsec VPN client software. The FortiClient Endpoint Security application, for example, can import and store the certificates required by VPN connections.

FortiGate units are also compatible with some Public Key Infrastructure systems. For an example of this type of system, see RSA ACE (SecurID) servers on page 44.

Server-based password authentication

Using external authentication servers is desirable when multiple FortiGate units need to authenticate the same users, or where the FortiGate unit is added to a network that already contains an authentication server. FortiOS supports the use of LDAP, RADIUS, TACACS+, AD, or POP3 servers for authentication.

When you use an external authentication server to authenticate users, the FortiGate unit sends the user’s entered credentials to the external server. The password is encrypted. The server’s response indicates whether the supplied credentials are valid or not.

You must configure the FortiGate unit to access the external authentication servers that you want to use. The configuration includes the parameters that authenticate the FortiGate unit to the authentication server.

You can use external authentication servers in two ways:

• Create user accounts on the FortiGate unit. However, instead of storing each user’s password, specify the server used to authenticate that user. As with accounts that store the password locally, you add these users to appropriate user groups.
• Add the authentication server to user groups. Any user who has an account on the server can be authenticated and have the access privileges of the FortiGate user group. Optionally, when an LDAP server is a FortiGate user group member, you can limit access to users who belong to specific groups defined on the LDAP server.

Local password authentication

The simplest authentication is based on user accounts stored locally on the FortiGate unit. For each account, a username and password is stored. The account also has a disable option so that you can suspend the account without deleting it.

Local user accounts work well for a single-FortiGate installation. If your network has multiple FortiGate units that will use the same accounts, the use of an external authentication server can simplify account configuration and maintenance.

You can create local user accounts in the web-based manager under User & Device > User Definition. This page is also used to create accounts where an external authentication server stores and verifies the password.