This guide describes in detail how to configure the various features of the KEMP LoadMaster using the WUI. This document also describes the Web User Interface (WUI) of the KEMP LoadMaster. The available menu options in the LoadMaster may vary from the ones described in this document. The features available in a LoadMaster depend on what license is in place.


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Clicking the Home menu option displays the home page which presents a list of basic information regarding the LoadMaster.

Figure 2‑1: LoadMaster Vitals screen

Virtual Services

From this point onwards, the headings in this document generally correspond to the options in the main menu on the left of the LoadMaster WUI.

Add New

Figure 3‑1: Add a new Virtual Service screen.

Here the Virtual IP (VIP) address, port, protocol and name are defined. The VIP address, name and port are manually entered into the text boxes and the protocol is selected from the drop-down list.

If templates are installed on your machine, a Use Template drop-down list is available whereby you can select a template to configure the Virtual Service parameters such as port and protocol.

For the LoadMaster Exchange appliance there is a maximum limit of thirteen (13) Virtual Services that may be configured.

View/Modify (Existing HTTP Service)

Figure 3‑2: Virtual Services screen

This screen displays a list of Virtual Services on the LoadMaster, summarizing the main properties of each and giving the options to modify or delete services, or create a new service.


Delete is permanent, there is no UNDO feature. Use with care.

Each configured Virtual Service may be changed by clicking the Modify button or deleted by clicking the Delete button.

The Virtual Service status may be one of the following:

Up – At least one Real Server is available.

Down – No Real Servers are available.

Sorry – All Real Servers are down and traffic is routed to a separately configured Sorry Server that is not part of the Real Server set, with no health checking.

Disabled – The service has been administratively disabled.

Redirect – A fixed redirect response has been configured. Redirect Virtual Services can be created by using the Add a Port 80 Redirector VS option in the Advanced Properties section. For more information, refer to Section 3.6.

Fail Message – A fixed error message has been configured. A fixed error message can be specified using the Not Available Redirection Handling options. Refer to Section 3.6 for more information.

Unchecked – Health checking of the Real Servers has been disabled. All Real Servers are accessed and presumed UP.

Security Down – The LoadMaster is unable to reach the Authentication Server and will prevent access to any Virtual Service which has Edge Security Pack (ESP).

WAF Misconfigured – If the WAF for a particular Virtual Service is misconfigured, for example if there is an issue with a rule file, the status changes to WAF Misconfigured and turns red. If the Virtual Service is in this state, all traffic is blocked. AFP can be disabled for that Virtual Service to stop the traffic being blocked, if required, while troubleshooting the problem.

The image below shows the Virtual Service properties screen. It is composed of several component sections:

Figure 3‑3: Virtual Service Properties screen

Basic Properties - where the usual and most common attributes are set

Standard Options – the most widely used features of a Virtual Service

SSL Properties – if SSL acceleration is being used,it will show Acceleration Enabled and this section of the screen will be used to configure the SSL functions

Advanced Properties – the additional features for a Virtual Service

WAF Options – where the options relating to the Application Firewall Pack (AFP) can be set

ESP Options –where the options relating to ESP are set

Real Servers/SubVSs – where Real Servers/SubVSs are assigned to a Virtual Server

Depending upon the service type, and enabled or disabled features, specific fields and options show in the WUI. The screenshots in this document may not represent every possible configuration.

Basic Properties

Figure 3‑4: Basic Properties section

There are two buttons adjacent to the Basic Properties heading:
Duplicate VIP
This option makes a copy of the Virtual Service, including any related SubVSs. All Virtual Service configuration settings are copied to the duplicate Virtual Service. When this button is clicked, a screen appears where the IP address and port can be specified for the copied Virtual Service.
Change Address
Clicking this button opens a screen where the virtual IP address and port of the Virtual Service can be modified.
The fields in the Virtual Service modify screen are:
Service Name
This text box allows you to assign a nickname to the Virtual Service being created, or change an existing one.

In addition to the usual alphanumeric characters, the following ‘special’ characters can be used as part of the Service Name:

. @ - _

However, there must be at least one alphanumeric character before the special characters.

Alternate Address
This is where, if so desired, you would specify a secondary address in either IPv6 or IPv4 format.
Service Type
Setting the Service Type controls the options displayed for the Virtual Service. It’s important to make sure the Service Type is set according to the type of application that you are load balancing.

WebSocket Virtual Services must be get to the Generic Service Type.

The HTTP/2 Service Type allows HTTP/2 traffic - but does not currently offer any Layer 7 options beyond address translation (transparency, subnet originating, alternate source).

Activate or Deactivate Service
This check box gives you the option to activate or deactivate a Virtual Service. The default (active) is selected.

Standard Options

Figure 3‑5: Standard Options section

Force L7
If visible, Force L7 should be selected (default). If it is not selected, the Virtual Service will be forced to Layer 4.

L7 Transparency
Enabling this option makes the Virtual Service transparent (NO NAT). However, if the client resides on the same subnet as the Virtual IP and Real Servers, then the Virtual Services will automatically NAT the source IP (enabling non-transparency).

If the Real Servers considered local option is enabled, then the Real Servers, within a two-armed configuration, are considered local even if they are on a different arm of the configuration.

Subnet Originating Requests

This option is only available if Transparency is not enabled.

When transparency is not enabled, the source IP address of connections to the Real Servers is that of the Virtual Service. When transparency is enabled, the source IP address will be the IP address that is initiating connection to the Virtual Service. If the Real Server is on a subnet, and the Subnet Originating Requests option is enabled, then the subnet address of the LoadMaster will be used as the source IP address.

This switch allows control of subnet originating requests on a per-Virtual Service basis. If the global switch (Subnet Originating Requests in System Configuration > Miscellaneous Options > Network Options in the main menu) is enabled then it is enabled for all Virtual Services.

It is recommended that the Subnet Originating Requests option is enabled on a per-Virtual Service basis.

If the global option is not enabled, it can be controlled on a per-Virtual Service basis.

If this option is switched on for a Virtual Service that has SSL re-encryption enabled, all connections currently using the Virtual Service will be terminated.

Extra Ports
You may specify a range of ports, sequential or otherwise, starting with the base port already configured for the Virtual Service. The port numbers are inputted to the field and separated with a space, and the maximum range is 510 ports.

You can enter the extra ports either as port ranges or single ports separated by spaces or comma in whatever order you wish, for example, entering the list 8000-8080, 9002, 80, 8050, 9000 will add the ports 80, 8000 to 8080, 9000 and 9002.

Server Initiating Protocols
By default, the LoadMaster will not initiate a connection with a Real Server until it has received some data from a client. This prohibits certain protocols from working as they need to communicate with the Real Server before transmitting data.

If the Virtual Service uses one of these protocols then select the protocol from the drop-down list to enable it to work correctly.

The protocols that can be selected are:






Other Server Initiating Protocols

The Server Initiating Protocols option is not visible when the port specified in the Virtual Service is 80, 8080 or 443.

Persistence Options
Persistence is setup on a per Virtual Service basis. This section allows you to select whether persistence is enabled for this service, to set the type of persistence and the persistence timeout value.

If persistence is enabled it means that a client connection to a particular Real Server via the LoadMaster is persistent, in other words - the same client will subsequently connect to the same Real Server. The timeout value determines for how long this particular connection is remembered.

The drop-down list gives you the option to select the type of persistence. These are:

Source IP Address:

The source IP address (of the requesting client) is used as the key for persistency in this case.

Super HTTP:

Super HTTP is the recommended method for achieving persistence for HTTP and HTTPS services with the LoadMaster. It functions by creating a unique fingerprint of the client browser and uses that fingerprint to preserve connectivity to the correct Real Server. The fingerprint is based on the combined values of the User-Agent field and, if present, the Authorization header. Connections with the same header combination will be sent back to the same Real Server.

Server Cookie:

The LoadMaster checks the value of a specially set cookie in the HTTP header. Connections with the same cookie will go to the same Real Server.

Server Cookie or Source IP:

If cookie persistence fails, it reverts to source-based persistence.

Active Cookie:

The LoadMaster automatically sets the special cookie.

Active Cookie or Source IP:

If active cookie persistence fails, it reverts to source-based persistence.

Hash All Cookies:

The Hash All Cookies method creates a hash of the values of all cookies in the HTTP stream. Cookies with the same value will be sent to the same server for each request. If the values change, then the connection will be treated as a new connection and the client will be allocated to a server according to the load balancing algorithm.

Hash All Cookies or Source IP:

Hash All Cookies or Source IP is identical to Hash All Cookies, with the additional feature that it will fall back to Source IP persistence in the event no cookies are in the HTTP string.

Super HTTP and Source IP Address:

This is the same as super HTTP but it also appends the source IP address to the string, thus improving the distribution of the resulting HASH.

URL Hash:

With URL Hash persistence, the LoadMaster will send requests with the same URL to the same server.

HTTP Host Header:

With HTTP Host Header persistence, the LoadMaster will send all requests that contain the same value in the HTTP Host: header to the same server.

Hash of HTTP Query Item:

This method operates in exactly the same manner as Server Persistence, except that the named item being inspected is a Query Item in the Query String of the URL. All queries with the same Query Item value will be sent to the same server.

Selected Header:

With Selected Header persistence, the LoadMaster will send all requests that contain the same value in the specified header to the same server.

SSL Session ID:

Each session over SSL has its own session ID which can be persisted on.

For this option to appear as a persistence method, the Virtual Service needs to have a Service Type of Generic and SSL acceleration must be disabled.

If a Virtual Service is an SSL service and not offloaded, the LoadMaster cannot meaningfully interact with any of the data in the stream at Layer 7. The reason is, the data is encrypted and the LoadMaster has no way of decrypting it.

If, in the above scenario, a persistence mode that is not based off source IP is required, this is the only other option. When an SSL session is started, it generates a session ID for the connection. This session ID can be used to cause the client to persist to the correct server.

There are some downsides to this however, as most modern browsers regenerate the session ID at very short intervals, basically overwriting it, even if there is a longer interval set on the persist timeout.

UDP Session Initiation Protocol (SIP):

This persistence mode is only available in a UDP Virtual Service when Force L7 is enabled. SIP uses request and response transactions, similar to HTTP. An initial INVITE request is sent, which contains a number of header fields. These header fields can be used for persistence.

When any persistence mode is selected, a Timeout drop-down list appears. This allows you to set the length of time after the last connection that the LoadMaster will remember the persistence information.

Header field name
When UDP Session Initiation Protocol is selected as the persistence mode is selected sin the LoadMaster, a text box called Header field name will appear. The header field that is to be used as the basis for the persistence information should be entered here.

Scheduling Methods
This section allows you to select the method by which the LoadMaster will select a Real Server, for this particular service. The scheduling methods are as follows:

Round Robin:

Round Robin causes the LoadMaster to assign Real Servers to a session in order, i.e. the first session connects to Real Server 1, the second to Real Server 2 etc. There is no bias in the way the Real Servers are assigned.

Weighted Round Robin:

This method uses the weight property of the Real Servers to determine which Real Servers get preference. The higher the weight a Real Server has, the higher the proportion of connections it will receive.

Least Connection:

With this method, the current Real Server with the fewest open connections is assigned to the session.

Weighted Least Connection:

As with Least Connection, but with a bias relative to the weight.

Resource Based (Adaptive):

Adaptive scheduling means that the load on the Real Servers is periodically monitored and that packets are distributed such that load will be approximately equal for all machines. More details can be found in the section covering scheduling methods.

Resource Based (SDN Adaptive):A Virtual Service which is using an adaptive scheduling method (whether using SDN or not) can be viewed as a control system. The intent is to achieve an evenly distributed load over the Real Servers and the controller calculates an error value from this (that describes the deviation from the desired even distribution). It also calculates a set of control values (Real Server weights) that are fed back into the system in a way to decrease the error value.

Fixed Weighting:

All traffic goes to highest weight Real Server that is available. Real Servers should be weighted at the time they are create and no two Real Servers should have same weight, otherwise unpredictable results may occur.

Weighted Response Time:

Every 15 seconds the LoadMaster measures the time it takes for a response to arrive for a health check probe and uses this time to adjust the weights of the Real Servers accordingly, i.e. a faster response time relative to the other Real Servers leads to a higher weight which in turn leads to more traffic sent to that server.

Source IP Hash:

Instead of using the weights or doing round robin, a hash of the source IP is generated and used to find the correct real server. This means that the real server is always the same from the same host.You do not need any source IP persistence.

Because this method relies solely on the client (source) IP address and ignores current server load, using this method can lead to a particular Real Server becoming overloaded, or a general traffic imbalance across all Real Servers.

Idle Connection Timeout (Default 660)
The seconds before an idle connection is closed. There are some special values that can be set for this field:

Setting it to 0 will ensure that the default L7 connection timeout will be used. The default Connection Timeout value can be modified by going to System Configuration > Miscellaneous Options > Network Options.

Setting it to 1 will discard the connection after the packet is first forwarded – a response is not expected or handled

Setting it to 2 will use a DNS type of operation. The connection is dropped after the reply message.

Setting the Idle Connection Timeout to the special values of 1 or 2 allow better performance and memory usage for UDP connections and they correspond better to how UDP is used.

Quality of Service
The Quality of Service drop-down sets a Differentiated Services Code Point (DSCP) in the IP header of packets that leave the Virtual Service. This means that the next device or service that deals with the packets will know how to treat and prioritise this traffic. Higher priority packets are sent from the LoadMaster before lower priority packets.

The different options are described below:

Normal-Service: No special priority given to the traffic

Minimize-Cost: Used when data needs to be transferred over a link that has a lower “cost”

Maximize-Reliability: Used when data needs to travel to the destination over a reliable link and with little or no retransmission

Maximize-Throughput: Used when the volume of data transferred during an interval is important, even if the latency over the link is high

Minimize-Delay: Used when the time required (latency) for the packet to reach the destination must be low. This option has the quickest queue of each of the Quality of Service choices.

The Quality of Service feature only works with Layer 7 traffic. It does not work with Layer 4 traffic.

Use Address for Server NAT
By default, when the LoadMaster is being used to SNAT Real Servers, the source IP address used on the internet is that of the LoadMaster. The Use Address for Server NAT option allows the Real Servers configured on the Virtual Service to use the Virtual Service as the source IP address instead.

This option is most useful for services such as SMTP when the LoadMaster is in a public domain and when the service requires a reverse DNS check to see if the source address sent from the LoadMaster is the same as the Mail Exchanger (MX) record of the sender.

If the Real Servers are configured on more than one Virtual Service which has this option set, only connections to destination port 80 will use this Virtual Service as the source IP address.

The Use Address for Server NAT option only works on Virtual Services which are operating on the default gateway. This option is not supported on non-default gateway interfaces.

SSL Properties

Figure 3‑6: SSL Properties section

SSL Acceleration
This checkbox appears when the criteria for SSL Acceleration have been met, and serves to activate SSL Acceleration.

Enabled: If the Enabled check box is selected, and there is no certificate for the Virtual Service, you will be prompted to install a certificate. A certificate can be added by clicking the Manage Certificates button and importing or adding a certificate.

Reencrypt: Selecting the Reencrypt checkbox re-encrypts the SSL data stream before sending it to the Real Server.

Reversed: Selecting this checkbox will mean that the data from the LoadMaster to the Real Server is re-encrypted. The input stream must not be encrypted. This is only useful in connection with a separate Virtual Service which decrypts SSL traffic then uses this Virtual Service as a Real Service and loops data back to it. In this way, the client to real server data path is always encrypted on the wire.

Supported Protocols
The checkboxes in the Supported Protocols section allow you to specify which protocols should be supported by the Virtual Service. By default, the three TLS protocols are enabled and SSLv3 is disabled.

Require SNI hostname
If require Server Name Indication (SNI) is selected, the hostname will always be required to be sent in the TLS client hello message.

When Require SNI hostname is disabled, the first certificate will be used if a host header match is not found.

When Require SNI hostname is enabled, a certificate with a matching common name must be found, otherwise an SSL error is yielded. Wildcard certificates are also supported with SNI.

When using a Subject Alternative Name (SAN) certificate, alternate source names are not matched against the host header.

Wildcard certificates are supported but please note that the root domain name will not be matched as per RFC 2459. Only anything to the left of the dot will be matched. Additional certificates must be added to match the root domain names. For example, www.kemptechnologies.com will be matched until a wildcard of *.kemptechnologies.com. Kemptechnologies.com will not be matched.

To send SNI host information in HTTPS health checks, please enable Use HTTP/1.1 in the Real Servers section of the relevant Virtual Service(s) and specify a host header. If this is not set, the IP address of the Real Server will be used.

Available certificates will be listed in the Available Certificates select list on the left. To assign or unassign a certificate, select it and click the right or left arrow button. Then click Set Certificates. Multiple certificates can be selected by holding Ctrl on your keyboard and clicking each required certificate.

Reencryption Client Certificate
With SSL connections, the LoadMaster gets a certificate from the client and also gets a certificate from the server. The LoadMaster transcribes the client certificate in a header and sends the data to the server. The server still expects a certificate. This is why it is preferable to install a pre-authenticated certificate in the LoadMaster.

Reencryption SNI Hostname
Specify the Server Name Indication (SNI) hostname that should be used when connecting to the Real Servers.

This field is only visible when SSL re-encryption is enabled.

Cipher Set
A cipher is an algorithm for performing encryption or decryption.
Each Virtual Service (which has SSL Acceleration enabled) has a cipher set assigned to it. This can either be one of the system-defined cipher sets or a user-customized cipher set. The system-defined cipher sets can be selected to quickly and easily select and apply the relevant ciphers.

The system-defined cipher sets are as follows:

Default: The current default set of ciphers in the LoadMaster.

Default_NoRc4: The Default_NoRc4 cipher set contains the same ciphers as the default cipher set, except without the RC4 ciphers (which are considered to be insecure).

BestPractices: This is the recommended cipher set to use. This cipher set is for services that do not need backward compatibility - the ciphers provide a higher level of security. The configuration is compatible with Firefox 27, Chrome 22, IE 11, Opera 14 and Safari 7.

Intermediate_compatibility: For services that do not need compatibility with legacy clients (mostly Windows XP), but still need to support a wide range of clients, this configuration is recommended. It is compatible with Firefox 1, Chrome 1, IE 7, Opera 5 and Safari 1.

Backward_compatibility: This is the old cipher suite that works with clients back to Windows XP/IE6. This should be used as a last resort only.

FIPS: Ciphers which conform to FIPS (Federal Information Processing Standards).

Legacy: This is the set of ciphers that were available on the old LoadMaster firmware (v7.0-10) before OpenSSL was updated.

Refer to the SSL Accelerated Services, Feature Description for a full list of the ciphers supported by the LoadMaster, and a breakdown of what ciphers are in each of the system-defined cipher sets.

KEMP Technologies can change the contents of these cipher sets as required based on the best available information.

The list of ciphers which are assigned to a Virtual Service can be edited by clicking the Modify Cipher Set button. If changes are made to a preconfigured cipher set, a new custom cipher set will be created. Custom cipher sets can be named and can be used across different Virtual Services.

By default, the name for the custom cipher set will be Custom_

. KEMP recommends changing the name of custom cipher sets because if another system-defined cipher set is modified, the name will again default to Custom_

and will overwrite any existing cipher sets with that name.

It is not possible to modify the list of ciphers in a system-defined cipher set. Instead, a new custom cipher set will be created when changes are made to the ciphers list.

It is not possible to delete a custom cipher set in the LoadMaster WUI. However, it is possible to delete a cipher set using the RESTful API.

When a cipher set is selected and applied, the Ciphers list is read only. To modify the ciphers that are assigned to a Virtual Service, either change the assigned Cipher Set or click Modify Cipher Set.

When modifying a cipher set, available ciphers are listed on the left. Ciphers can be assigned or unassigned by selecting them and clicking the right or left arrow buttons. Then, specify a name for the custom cipher set and click Save Cipher Set. Multiple ciphers can be selected by holding the Ctrl key on your keyboard and selecting the required ciphers.

Client Certificates

No Client Certificates required: enables the LoadMaster to accept HTTPS requests from any client. This is the recommended option.

By default the LoadMaster will accept HTTPS requests from any client. Selecting any of the other values below will require all clients to present a valid client certificate. In addition, the LoadMaster can also pass information about the certificate to the application.

This option should not be changed from the default of No Client Certificates required. Only change from the default option if you are sure that all clients that access this service have valid client certificates.

Client Certificates required: requires that all clients forwarding a HTTPSrequest must present a valid client certificate.

Client Certificates and add Headers: requires that all clients forwarding a HTTPS request must present a valid client certificate. The LoadMaster also passes information about the certificate to the application by adding headers.

The below options send the certificate in its original raw form. The different options let you specify the format that you want to send the certificate in:

Client Certificates and pass DER through as SSL-CLIENT-CERT

Client Certificates and pass DER through as X-CLIENT-CERT

Client Certificates and pass PEM through as SSL-CLIENT-CERT

Client Certificates and pass PEM through as X-CLIENT-CERT

Verify Client using OCSP
Verify (via Online Certificate Status Protocol (OCSP)) that the client certificate is valid.

This option is only visible when ESP is enabled.

Advanced Properties

Figure 3‑7: Advanced Properties section

Content Switching
Clicking the Enable button, enables rule-based Content Switching on this Virtual Service. Once enabled,
rules must be assigned to the various Real Servers. Rules can be attached to Real Server by clicking the

None button located next the Real Server. Once rules are attached to a Real Server the None button will display the count of rules attached.

Rules Precedence
Clicking the Rules Precedence button displays the order in which Content Switching rules are applied. This option only appears when Content Switching and when rules are assigned to the Real Server(s).

Figure 3‑8: Request Rules

This screen shows the Content Switching rules that are assigned to the Real Servers of the Virtual Services and the order in which they apply. A rule may be promoted in the order of precedence by clicking its corresponding Promote button.

HTTP Selection Rules
Show the selection rules that are associated with the Virtual Service.

HTTP Header Modifications
Clicking the Show Header Rules button displays the order in which Header Modification rules are implemented. The number of rules (of both request and response type) is displayed on the actual button.

Figure 3‑9: Modification Rules

From within the screen you can Add and Delete Header Modification rules. The order in which the rules are applied can be changed by clicking the Promote buttons.

Enable Caching
This option enables caching of static content. This saves valuable Real Server processing power and bandwidth. Caching can be enabled per HTTP and offloaded HTTPS Virtual Services.

Types of file that can be cached may be defined in AFE configuration under the Systems Configuration > Miscellaneous Options menu.

Maximum Cache Usage
This option limits the size of the cache memory per Virtual Service. For example, two Virtual Services, each running with a limit of 50% will use 100% of the cache store. The default is No Limit. It is recommended to limit the cache size to prevent unequal use of the cache store. Ensure that the cache maximum usage is adjusted so that each Virtual Service has a percentage of cache to use. If there is not remaining space to be allocated for a cache enabled Virtual Service, that service will not cache content.

Enable Compression
Files sent from LoadMaster are compressed with Gzip.

If compression is enabled without caching, LoadMaster performance may suffer.
The types of file that can be compressed may be defined in AFE configuration in the Systems

Configuration > Miscellaneous section of the LoadMaster WUI.

Compression is not recommended for files 100MB or greater in size

Detect Malicious Requests
The Intrusion Prevention System (IPS) service will provide in-line protection of Real Server(s) by providing real-time mitigation of attacks and isolation of Real Server(s). Intrusion prevention is based on the industry standard SNORT database and provides real-time intrusion alerting.

To get updated or customized rules, please refer to the SNORT website: https://www.snort.org/.
Selecting the Detect Malicious Requests check box enables the IPS per HTTP and offloaded HTTPS Virtual Services. There are two options for handling of requests that match a SNORT rule. Drop Connection, where a rule match will generate no HTTP response, or Send Reject, where a rule match will generate a response to the client of HTTP 400 “Invalid Request”. Both options prevent the request from reaching the Real Server(s).

Enable Multiple Connect
Enabling this option permits the LoadMaster to manage connection handling between the LoadMaster and the Real Servers. Requests from multiple clients will be sent over the same TCP connection.

Multiplexing only works for simple HTTP GET operations. The Enable Multiple Connect check box will not be available in certain situations, for example if WAF, ESP or SSL Acceleration is enabled.

Port Following
Port following enables a switch from an HTTP connection to an HTTPS (SSL) connection to be persistent on the same Real Server. Port following is possible between UDP and TCP connections.
To switch on port following, the following must be true:

The Virtual Service where port following is being switched on must be an HTTPS service

There must be a HTTP service

Both of these Virtual Services must the same Layer 7 persistence modeselected, i.e. Super HTTP or Source IP Address persistence

Port following is not available on SubVSs.

Add Header to Request
Input the key and the value for the extra header that is to be inserted into every request sent to the Real Servers.

Click the Set Header button to implement the functionality.

Add HTTP Headers

The Add HTTP Headers drop-down list is only available when SSL offloading (SSL Acceleration) is enabled.

This option allows you to select which headers are to be added to the HTTP stream. The options available include:

Legacy Operation(XXX)



X-Forwarded-For (No Via)


X-ClientSide (No Via)

Via Only

In the Legacy operation, if the system is in HTTP kernel mode, then a header is added. Otherwise nothing is done. For the other operation methods, then the system is forced into HTTP kernel mode and the specified operation is performed.

Sorry Server
Enter the IP Address and Port number in the applicable fields. If no Real Servers are available, the LoadMaster will redirect to a specified location, with no checking. The IP address of a Sorry Server must be on a network or subnet that is defined on the LoadMaster.

When using a Layer 7 Virtual Service with transparency enabled, the Sorry Server should be on the same subnet as the Real Server.

Not Available Redirection Handling
When no Real Servers are available to handle the request you can define the error code and URL that the client should receive.

Error Code: If no Real Servers are available, the LoadMaster can terminate the connection with a HTTP error code. Select the appropriateerror code.

Redirect URL: When there are no Real Servers available and an error response is to be sent back to the client, a redirect URL can also be specified. If the string entered in this text box does not include http:// or https:// the string is treated as being relative to the current location, so the hostname will be added to the string in the redirect. This field also supports the use of wildcards such as %h and %swhich represent the requested hostname and Uniform Resource Identifier (URI) respectively.

Error Message: When no Real Servers are available and an error response is to be sent back to the client, the specified error message will be added to the response.

For security reasons, the returned HTML page only returns the text Document has moved. No request-supplied information is returned.

Error File:When no Real Servers are available and an error response is to be sent back to the client, the specified file will be added to the response. This enables simple error HTML pages to be sent in response to the specified error.

The maximum size of this error page is 16KB.
Not Available Server/Port

Figure 3‑10: Not Available Server

In a UDP Virtual Service there is an option to specify a Not Available Server and Port. When there are no Real Servers available to handle the request this option defines the URL that the client will receive.

The value of the Not Available Server can only be changed for UDP if the service is not currently using the Not Available Server.

Add a Port 80 Redirector VS
If no port 80 Virtual Service is configured, one can be created. It will then redirect the client to the URL specified in the Redirection URL: field.

Click the Add HTTP Redirector button to implement the redirector.

When the Add HTTP Redirector button is clicked, a redirect Virtual Service is created and this WUI option disappears from the relevant Virtual Service.

Default Gateway
Specify the Virtual Service-specific gateway to be used to send responses back to the clients. If this is not set, the global default gateway will be used.

Click the Set Default Gateway button to implement the default gateway.

If the global Use Default Route Only option is set in System Configuration > Miscellaneous Options > Network Options, traffic from Virtual Services that have the Default Gateway set will be only routed to the interface where the Virtual Service’s default route is located. This can allow the LoadMaster to be directly connected to client networks without returning traffic directly using the adjacent interface.

Alternate Source Addresses
If no list is specified, the LoadMaster will use the IP address of the Virtual Service as its local address. Specifying a list of addresses ensures the LoadMaster will use these addresses instead.

Click the Set Alternate Source Addresses button to implement the Alternate Source Addresses.

This option is only available if the Allow connection scaling over 64K Connections option is enabled in the L7 Configurationscreen.

Service Specific Access Control
Allows you to change the Virtual Service-specific Access Control lists.

If you implement the Access Control Lists option, the Extra Ports option will not work correctly.

Web Application Firewall (WAF) Options

Figure 3‑11: AFP Options

The Web Application Firewall (WAF) feature must be enabled before you can configure these options.

Figure 3‑12: Enable AFP

To enable WAF, select the Enabled check box. A message will be displayed next to the Enabled check box displaying how many WAF-enabled Virtual Services exist and it will also display the maximum number of WAF-enabled Virtual Services that can exist. If the maximum number of WAF-enabled Virtual Services have been reached, the Enabled check box will be greyed out.

Utilizing WAF can have a significant performance impact on your LoadMaster deployment. Please ensure that the appropriate resources are allocated.

For virtual and bare metal LoadMaster instances, a minimum of 2GB of allocated RAM is required for operation of AFP. The default memory allocation for Virtual LoadMasters and LoadMaster Bare Metal instances prior to LoadMaster Operating System version 7.1-22 is 1GB of RAM. If this default allocation has not been changed please modify the memory settings before attempting to proceed with AFP configuration.

Default Operation
Select the default operation of the WAF:

Audit Only: This is an audit-only mode – logs will be created but requests and responses are not blocked.

Block Mode: Either requests or responses are blocked.

Audit mode
Select what logs to record:

No Audit: No data is logged.

Audit Relevant: Logs data which is of a warning level and higher. This is the default option for this setting.

Audit All: Logs all data through the Virtual Service.

Selecting the Audit All option produces a large amount of log data. KEMP does not recommend selecting the Audit All option for normal operation. However, the Audit All option can be useful when troubleshooting a specific problem.

Inspect HTML POST Request Content
Enable this option to also process the data supplied in POST requests.

Two additional options (Disable JSON Parser and Disable XML Parser) only become available if Inspect HTML Post Request Content is enabled.

Disable JSON Parser
Disable processing of JavaScript Object Notation (JSON) requests.

Disable XML Parser
Disable processing of XML requests.

Process Responses
Enable this option to verify responses sent from the Real Servers.

This can be CPU and memory intensive.

If a Real Server is gzip encoding, WAF will not check that traffic, even if Process Responses is enabled.
Hourly Alert Notification Threshold

This is the threshold of incidents per hour before sending an alert. Setting this to 0 disables alerting.

This is where you can assign/un-assign generic, custom, application-specific and application-generic rules to/from the Virtual Service.

You cannot assign application-specific and application-generic rules to the same Virtual Service.

Edge Security Pack (ESP) Options
The ESP feature must be enabled before you can configure these options. To enable the ESP function, please select the Enable ESP check box.

Figure 3‑13: SP Options section

The full ESP Options screen will appear.

The ESP feature can only be enabled if the Virtual Service is a HTTP, HTTPS or SMTP Virtual Service

Figure 3‑14: ESP Options

Enable ESP
Enable or disable the ESP feature set by selecting or removing the checkmark from the Enable ESP checkbox.

ESP Logging
There are three types of logs stored in relation to the ESP feature. Each of these logs can be enabled or disabled by selecting or deselecting the relevant checkbox. The types of log include:

User Access:logs recording all user logins

Security: logs recording all security alerts

Connection:logsrecording each connection

Logs are persistent and can be accessed after a reboot of the LoadMaster.

Client Authentication Mode
Specifies how clients attempting to connect to the LoadMaster are authenticated. The following types of methods are available:

Delegate to Server:the authentication is delegated to the server

Basic Authentication: standard Basic Authentication is used

Form Based: clients must enter their user details within a form to be authenticated on the LoadMaster

Client Certificate: clients must present the certificate which is verified against the issuing authority

NTLM: NTLM credentials are based on data obtained during the interactive logon process and consist of a domain name and a user name

The remaining fields in the ESP Options section will change based on the Client Authentication Mode selected.

SSO Domain
Select the Single Sign-On (SSO) Domain within which the Virtual Service will be included.

An SSO Domain must be configured in order to correctly configure the ESP feature.

Only SSO domains with the Configuration type of Inbound Configuration will be shown as options in this SSO Domain field.

Alternative SSO Domains
Many organizations use extranets to share information with customers and partners. It is likely that extranet portals will have users from two or more Active Directory domains. Rather than authenticating users from individual domains one at a time, assigning Alternative SSO Domains gives the ability to simultaneously authenticate users from two or more domains using one Virtual Service.

This option appears only when more than one domain has been configured.

Currently this option is available for domains which are configured with the following Authentication Protocols:




Figure 3‑15: Enabled and Reencrypt tick boxes selected

Before configuring the ESP Options to use Alternative SSO Domains ensure that, in the SSL Properties section, the Enabled and Reencrypt tick boxes are selected.

Figure 3‑16: Available Domains

The domain name which appears in the SSO Domain drop-down list is the default domain. This is also the domain which will be used if only one is configured.

Previously configured alternative domains appear in the Available Domain(s) list.

Figure 3‑17: Alternative Domains (SECOND and THIRD) Assigned to the Virtual Service.

To assign alternative SSO Domains:

Highlight each of the domains you wish to assign and click the > button.

An assigned domain is a domain which can be authenticated using a particular Virtual Service.

All domains which appear as available may be assigned to a Virtual Service.

Click the Set Alternative SSO Domains button to confirm the updated list of Assigned Domain(s).

Choose Basic Authentication from the Server Authentication Mode drop-down list.

When logging in to a domain using the ESP form, users should enter the name of the SSO Domain if an alternative domain needs to be accessed. If no domain name is entered in the username, users are, by default, logged on the domain entered in the default SSO Domain drop-down list.

To view the status of the Virtual Services, click Virtual Services and View/Modify Services in the main menu.

A list of the Virtual Services displays showing the current status of each service.
If alternative domains are assigned and there is an issue with a particular domain, the affected domain name is indicated in the Status column.

Allowed Virtual Hosts
The Virtual Service will only be allowed access to specified virtual hosts. Any virtual hosts that are not specified will be blocked.

Enter the virtual host name(s) in the Allowed Virtual Hosts field and click the Set Allowed Virtual Hosts button to specify the allowed virtual hosts.

Multiple domains may be specified within the field allowing many domains to be associated with the Single Sign On Domain.

The use of regular expressions is allowed within this field.

If this field is left blank, the Virtual Service will be blocked.

Allowed Virtual Directories
The Virtual Service will only be allowed access to the specified virtual directories, within the allowed virtual hosts. Any virtual directories that are not specified will be blocked.

Enter the virtual directory name(s) in the Allowed Virtual Directories field and click the Set Allowed

Virtual Directories button to specify the allowed virtual directories.
The use of regular expressions is allowed within this field.

Pre-Authorization Excluded Directories
Any virtual directories specified within this field will not be pre-authorized on this Virtual Service and will be passed directly to the relevant Real Servers.

Permitted Groups
Specify the groups that are allowed to access this Virtual Service. When set, if a user logs in to a service published by this Virtual Service, the user must be a member of at least one of the groups specified. Up to 10 groups are supported per Virtual Service. Performance may be impacted if a large number of groups are entered. Groups entered in this field are validated via an LDAP query.
Some guidelines about this field are as follows:

The group(s) specified must be valid groups on the Active Directory in the SSO domain associated with the Virtual Service. The SSO domain in the LoadMaster must be set to the directory for the groups. For example, if the SSO domain in the LoadMaster is set to webmail.example and webmail is not the directory for the groups, it will not work. Instead, the SSO domain may need to be set to .example.com.

The group(s) listed must be separated by a semi-colon

A space-separated list does not work because most groups contain a space in the name, for example Domain Users.

The following characters are not allowed in permitted group names:/ : + *

The authentication protocol of the SSO domain must be LDAP

The groups should be specified by name, not by full distinguished name

Include Nested Groups
This field relates to the Permitted Groups setting. Enable this option to include nested groups in the authentication attempt. If this option is disabled, only users in the top-level group will be granted access. If this option is enabled, users in both the top-level and first sub-level group will be granted access.

SSO Image Set
This option is only available if Form Based is selected as the Client Authentication Mode. You can choose which form to use to gather the Username and Password. There are three form options, Exchange, Blank and Dual Factor Authentication. There are also options to display the form and error messages in other languages.

Exchange Form

Figure 3‑18: Exchange form

The Exchange Form contains the KEMP Logo

Blank Form

Figure 3‑19: Blank form

The Blank Form does not contain the large KEMP logo.

Dual Factor Authentication

Figure 3‑20: Dual Factor Authentication form

The Dual Factor Authentication form contains four fields - two for the remote credentials and two for the internal credentials.

Remote Credentials are credentials that are used to authenticate against remote authentication servers such as RADIUS, before allowing the user to authenticate against Domain Servers such as Active Directory servers.

Internal Credentials are credentials that ar

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