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> Chapter 35 - WAN Optimization, Web Cache, Explicit Proxy, and WCCP > Peers and authentication groups

Peers and authentication groups

All communication between WAN optimization peers begins with one WAN optimization peer (or client-side FortiGate unit) sending a WAN optimization tunnel request to another peer (or server-side FortiGate unit). During this process, the WAN optimization peers identify and optionally authenticate each other.

Basic WAN optimization peer requirements

WAN optimization requires the following configuration on each peer. For information about configuring local and peer host IDs, see Configuring peers.

  • The peer must have a unique host ID.
  • Unless authentication groups are used, peers authenticate each other using host ID values. Do not leave the local host ID at its default value.
  • The peer must know the host IDs and IP addresses of all of the other peers that it can start WAN optimization tunnels with. This does not apply if you use authentication groups that accept all peers.
  • All peers must have the same local certificate installed on their FortiGate units if the units authenticate by local certificate. Similarly, if the units authenticate by pre-shared key (password), administrators must know the password. The type of authentication is selected in the authentication group. This applies only if you use authentication groups.

Accepting any peers

Strictly speaking, you do not need to add peers. Instead you can configure authentication groups that accept any peer. However, for this to work, both peers must have the same authentication group (with the same name) and both peers must have the same certificate or pre-shared key.

Accepting any peer is useful if you have many peers or if peer IP addresses change. For example, you could have many travelling FortiClient peers with IP addresses that are always changing as the users travel to different customer sites. This configuration is also useful if you have FortiGate units with dynamic external IP addresses (using DHCP or PPPoE). For most other situations, this method is not recommended and is not a best practice as it is less secure than accepting defined peers or a single peer. For more information, see Configuring authentication groups.

How FortiGate units process tunnel requests for peer authentication

When a client-side FortiGate unit attempts to start a WAN optimization tunnel with a peer server-side FortiGate unit, the tunnel request includes the following information:

  • the client-side local host ID
  • the name of an authentication group, if included in the rule that initiates the tunnel
  • if an authentication group is used, the authentication method it specifies: pre-shared key or certificate
  • the type of tunnel (secure or not).

For information about configuring the local host ID, peers and authentication groups, see Configuring peers and Configuring authentication groups.

The authentication group is optional unless the tunnel is a secure tunnel. For more information, see Secure tunneling.

If the tunnel request includes an authentication group, the authentication will be based on the settings of this group as follows:

  • The server-side FortiGate unit searches its own configuration for the name of the authentication group in the tunnel request. If no match is found, the authentication fails.
  • If a match is found, the server-side FortiGate unit compares the authentication method in the client and server authentication groups. If the methods do not match, the authentication fails.
  • If the authentication methods match, the server-side FortiGate unit tests the peer acceptance settings in its copy of the authentication group.
  • If the setting is Accept Any Peer, the authentication is successful.
  • If the setting is Specify Peer, the server-side FortiGate unit compares the client-side local host ID in the tunnel request with the peer name in the server-side authentication group. If the names match, authentication is successful. If a match is not found, authentication fails.
  • If the setting is Accept Defined Peers, the server-side FortiGate unit compares the client-side local host ID in the tunnel request with the server-side peer list. If a match is found, authentication is successful. If a match is not found, authentication fails.

If the tunnel request does not include an authentication group, authentication will be based on the client-side local host ID in the tunnel request. The server-side FortiGate unit searches its peer list to match the client-side local host ID in the tunnel request. If a match is found, authentication is successful. If a match is not found, authentication fails.

If the server-side FortiGate unit successfully authenticates the tunnel request, the server-side FortiGate unit sends back a tunnel setup response message. This message includes the server-side local host ID and the authentication group that matches the one in the tunnel request.

The client-side FortiGate unit then performs the same authentication procedure as the server-side FortiGate unit did. If both sides succeed, tunnel setup continues.

Configuring peers

When you configure peers, you first need to add the local host ID that identifies the FortiGate unit for WAN optimization and then add the peer host ID and IP address of each FortiGate unit with which a FortiGate unit can create WAN optimization tunnels.

To configure WAN optimization peers - web-based manager:
  1. Go to WAN Opt. & Cache > Peers.
  2. For Local Host ID, enter the local host ID of this FortiGate unit and select Apply. If you add this FortiGate unit as a peer to another FortiGate unit, use this ID as its peer host ID.

    The local or host ID can contain up to 25 characters and can include spaces.
  3. Select Create New to add a new peer.
  4. For Peer Host ID, enter the peer host ID of the peer FortiGate unit. This is the local host ID added to the peer FortiGate unit.
  5. For IP Address, add the IP address of the peer FortiGate unit. This is the source IP address of tunnel requests sent by the peer, usually the IP address of the FortiGate interface connected to the WAN.
  6. Select OK.
To configure WAN optimization peers - CLI:

In this example, the local host ID is named HQ_Peer and has an IP address of 172.20.120.100. Three peers are added, but you can add any number of peers that are on the WAN.

  1. Enter the following command to set the local host ID to HQ_Peer.

config wanopt settings

set host-id HQ_peer

end

  1. Enter the following commands to add three peers.

config wanopt peer

edit Wan_opt_peer_1

set ip 172.20.120.100

next

edit Wan_opt_peer_2

set ip 172.30.120.100

next

edit Wan_opt_peer_3

set ip 172.40.120.100

end

Configuring authentication groups

You need to add authentication groups to support authentication and secure tunneling between WAN optimization peers.

To perform authentication, WAN optimization peers use a certificate or a pre-shared key added to an authentication group so they can identify each other before forming a WAN optimization tunnel. Both peers must have an authentication group with the same name and settings. You add the authentication group to a peer-to-peer or active rule on the client-side FortiGate unit. When the server-side FortiGate unit receives a tunnel start request from the client-side FortiGate unit that includes an authentication group, the server-side FortiGate unit finds an authentication group in its configuration with the same name. If both authentication groups have the same certificate or pre-shared key, the peers can authenticate and set up the tunnel.

Authentication groups are also required for secure tunneling.

To add authentication groups, go to WAN Opt. & Cache > Authentication Groups.

To add an authentication group - web-based manager:

Use the following steps to add any kind of authentication group. It is assumed that if you are using a local certificate to authenticate, it is already added to the FortiGate unit

  1. Go to WAN Opt. & Cache > Authentication Groups.
  2. Select Create New.
  3. Add a Name for the authentication group.

    You will select this name when you add the authentication group to a WAN optimization rule.
  4. Select the Authentication Method.

    Select Certificate if you want to use a certificate to authenticate and encrypt WAN optimization tunnels. You must select a local certificate that has been added to this FortiGate unit. (To add a local certificate, go to System > Certificates.) Other FortiGate units that participate in WAN optimization tunnels with this FortiGate unit must have an authentication group with the same name and certificate.

    Select Pre-shared key if you want to use a pre-shared key or password to authenticate and encrypt WAN optimization tunnels. You must add the Password (or pre-shared key) used by the authentication group. Other FortiGate units that participate in WAN optimization tunnels with this FortiGate unit must have an authentication group with the same name and password. The password must contain at least 6 printable characters and should be known only by network administrators. For optimum protection against currently known attacks, the key should consist of a minimum of 16 randomly chosen alphanumeric characters.
  5. Configure Peer Acceptance for the authentication group.

    Select Accept Any Peer if you do not know the peer host IDs or IP addresses of the peers that will use this authentication group. This setting is most often used for WAN optimization with the FortiClient application or with FortiGate units that do not have static IP addresses, for example units that use DHCP.

    Select Accept Defined Peers if you want to authenticate with peers added to the peer list only.

    Select Specify Peer and select one of the peers added to the peer list to authenticate with the selected peer only.

  6. Select OK.
  7. Add the authentication group to a WAN optimization rule to apply the authentication settings in the authentication group to the rule.
To add an authentication group that uses a certificate- CLI:

Enter the following command to add an authentication group that uses a certificate and can authenticate all peers added to the FortiGate unit configuration.

In this example, the authentication group is named auth_grp_1 and uses a certificate named Example_Cert.

config wanopt auth-group

edit auth_grp_1

set auth-method cert

set cert Example_Cert

set peer-accept defined

end

To add an authentication group that uses a pre-shared key - CLI:

Enter the following command to add an authentication group that uses a pre-shared key and can authenticate only the peer added to the authentication group.

In this example, the authentication group is named auth_peer, the peer that the group can authenticate is named Server_net, and the authentication group uses 123456 as the pre-shared key. In practice you should use a more secure pre-shared key.

config wanopt auth-group

edit auth_peer

set auth-method psk

set psk 123456

set peer-accept one

set peer Server_net

end

To add an authentication group that accepts WAN optimization connections from any peer - web-based manager

Add an authentication group that accepts any peer for situations where you do not have the Peer Host IDs or IP Addresses of the peers that you want to perform WAN optimization with. This setting is most often used for WAN optimization with the FortiClient application or with FortiGate units that do not have static IP addresses, for example units that use DHCP. An authentication group that accepts any peer is less secure than an authentication group that accepts defined peers or a single peer.

The example below sets the authentication method to Pre-shared key. You must add the same password to all FortiGate units using this authentication group.

  1. Go to WAN Opt. & Cache > Authentication Groups.
  2. Select Create New to add a new authentication group.
  3. Configure the authentication group:
Name Specify any name.
Authentication Method Pre-shared key
Password Enter a pre-shared key.
Peer Acceptance Accept Any Peer
To add an authentication group that accepts WAN optimization connections from any peer - CLI:

In this example, the authentication group is named auth_grp_1. It uses a certificate named WAN_Cert and accepts any peer.

config wanopt auth-group

edit auth_grp_1

set auth-method cert

set cert WAN_Cert

set peer-accept any

end

Secure tunneling

You can configure WAN optimization rules to use AES‑128bit‑CBC SSL to encrypt the traffic in the WAN optimization tunnel. WAN optimization uses FortiASIC acceleration to accelerate SSL decryption and encryption of the secure tunnel. Peer-to-peer secure tunnels use the same TCP port as non-secure peer-to-peer tunnels (TCP port 7810).

To use secure tunneling, you must select Enable Secure Tunnel in a WAN optimization rule and add an authentication group. The authentication group specifies the certificate or pre-shared key used to set up the secure tunnel. The Peer Acceptance setting of the authentication group does not affect secure tunneling.

The FortiGate units at each end of the secure tunnel must have the same authentication group with the same name and the same configuration, including the same pre-shared key or certificate. To use certificates you must install the same certificate on both FortiGate units.

For active-passive WAN optimization you can select Enable Secure Tunnel only in the active rule. In peer-to-peer WAN optimization you select Enable Secure Tunnel in the WAN optimization rule on both FortiGate units. For information about active-passive and peer-to-peer WAN optimization, see Manual (peer-to-peer) and active-passive WAN optimization

For a secure tunneling configuration example, see Example Adding secure tunneling to an active-passive WAN optimization configuration.

Monitoring WAN optimization peer performance

The WAN optimization peer monitor lists all of the WAN optimization peers that a FortiGate unit can perform WAN optimization with. These include peers manually added to the configuration as well as discovered peers.

The monitor lists each peer’s name, IP address, and peer type. The peer type indicates whether the peer was manually added or discovered. To show WAN optimization performance, for each peer the monitor lists the percent of traffic reduced by the peer in client-side WAN optimization configurations and in server-side configurations (also called gateway configurations).

To view the peer monitor, go to WAN Opt. & Cache > Peer Monitor.