Kemp Support, how can we help?

The latest application delivery knowledge and expertise at your fingertips.

LoadMaster Release Notes

LMOS Version is a feature and bug-fix release made available in April 2021. Please read the sections below before installing or upgrading to this GA release.


Before You Upgrade (READ ME FIRST)

Please pay special attention to the issues below before you begin an upgrade to this LMOS release.

Generation of 4096-bit DHE Key

During an upgrade to this version of LMOS from a version prior to, a new 4096-bit DHE key is generated. On smaller LoadMasters, this can lead to significant CPU and memory consumption that could impact regular virtual service traffic. So, Kemp strongly recommends that this update be performed in a maintenance interval. 

Best Practices Cipher Set

In LMOS, the BestPractices cipher set was updated. If you are upgrading from a version prior to, this change is effective immediately after upgrade to this release. This change was made to improve LoadMaster security and conform to the latest industry best practices.

If you depend on any of the cipher sets being removed from the BestPractices set, then before you upgrade you must create a custom cipher set that contains these ciphers and assign this new custom cipher set to the Virtual Services that are currently using the BestPractices cipher set. After this is done, you can upgrade to this release and your services will continue to use the old ciphers. If you do not, then after upgrade any clients that depend on these ciphers being available will no longer be able to connect.

It is recommended, however, that you migrate your services as soon as possible to use the new BestPractices cipher set. For more information on the cipher suites removed from the set, please see the LMOS Release Notes.

Supported Models for Upgrade

This release of LMOS is supported on the Hardware and Virtual models shown in the first three columns of the table below. It is not supported and should not be installed on any model listed in the two columns at right. This update patch can be applied to any supported model regardless of licensing (e.g., SPLA, MELA) or platform (e.g., hardware, local cloud, public cloud).

Supported Bare Metal Models UNSUPPORTED





If your model number is not listed above, please see the list of End of Life models.

Upgrade Path

You can upgrade to this release of LMOS from any previous 7.2.x release. For full upgrade path information, please see the article Kemp LoadMaster Firmware Upgrade Path.

Upgrade Patch XML File Verification Notes

By default, verification of the digital signature on upgrade images is required in LMOS and above. See the Update Verification Options setting under System Administration > Miscellaneous Options > WUI Settings. If the unit you are upgrading is set to require validation, you'll need to supply the XML Verification File supplied with this release.

Note that:

  • In previous releases, two verification files were provided: one for pre-7.2.51 systems and one for later systems. This restriction has been removed with this release; if upgrading from firmware / and above you can use the XML file provided with this release. If upgrading from any other firmware version you must following the upgrade path detailed in Kemp LoadMaster Firmware Upgrade Path article.
  • LoadMasters running an LMOS version prior to 7.2.49 do not provide the option of XML file verification in the UI or API. If you are upgrading from one of these releases to this release, you can verify the digital signatures offline using a manual process documented on the support website.

Downgrading to Earlier Versions

Downgrading a LoadMaster running LMOS to LMOS (or a later release) can be performed using any desired Update Verification Options setting.

Downgrading to LMOS or a previous release can only be done when the Update Verification Options setting is set to Optional or Legacy. When performing the downgrade, do not specify an XML file. If you want to verify the digital signature on the image before downgrading, you can do so using a manual process documented on the support website.

New Features

WAF Enhancements (WAF 1.5)

The following major enhancements to LoadMaster's WAF capabilities are included in LMOS 7.2.54.

Native Support for the OWASP Core Rule Set (CRS)

The OWASP CRS is a set of generic attack detection rules designed to protect web applications from a wide range of attacks, including the OWASP Top Ten. The CRS provides protection against many common attack categories, including SQL Injection, Cross Site Scripting, Local File Inclusion, and others, providing significantly better baseline protection for your applications as well as deeper insight into application traffic attacks.

Anomaly Scoring and Paranoia Modes

Support has been added for utilizing the anomaly scoring and paranoia modes available with the OWASP CRS to better enable tuning and reducing any false positives.

Enhanced Log Event Data

Additionally, real-time per Virtual Service logging of events and rules triggered whilst performing false positive analysis is available to make WAF operations more transparent to our customers.

User Interface Improvements

The LoadMaster user interface, for WAF, is being significantly modified to allow easy selection of countries to block and this will be reflected in enhanced statistics.

For more information, please see the WAF Feature Description.

Change Notices

WAF Rules being retired -- No Further Updates Available

With the introduction of the Open Web Application Security Project® (OWASP) Core Rule Set (CRS) as the primary set of rules-based protection on LoadMaster, the legacy WAF rules are being retired on 29th June 2021. After this date, you can continue to use the currently installed rules, but no further updates will be available. These legacy rules will remain available in the  LoadMaster user interface under the title ‘WAF Options (Legacy)’.

Issues Resolved

PD-18022 IPv6: If packet filtering is enabled, returning IPv6 traffic destined for a Real Server acting as a client is ignored by LoadMaster. This issue has been fixed.
PD-17940 Wildcard VS: After upgrade to 7.2.53, Loadmaster may reboot if a Wildcard Virtual Service exists and connections are not completed by the client. This bug has been fixed.
PD-17921 Body Response Content Rules: Fixed an issue where a body response rule applied to an empty file causes a significant response delay.
PD-17878 Bandwidth Limiting Statistics: Fixed an issue that caused incorrect client bandwidth limiting statistics to be displayed.
PD-17721 SSL Certificate Login: Fixed issues associated with rejecting certificates with an unknown user error when multiple "Other names" are specified in the certificate.
PD-17717 WAF: Addressed issues where a specific custom WAF rule could not be added because of internal dependencies within the standard rule set.
PD-17714 OIDC: In previous releases, the minimum allowed value for the Application Secret ID length was 32, which caused issues on some providers. With this release, the minimum value is 1.
PD-17694 User Interface: Fixed an issue with rendering the Network Telemetry interface table in some browsers.
PD-17693 ESP Logging: In previous releases, Layer 7 User Agent logs were appearing in the messages log file when accessing a Virtual Service using Single Sign On even when Layer 7 Debug Logs were not enabled. This issue has been fixed.
PD-17636 UDP Virtual Service: Fixed an issue that caused the system to panic when a UDP port 443 Virtual Service was created.
PD-17616 CSR Generation: In previous releases, the T61STRING string type was used for the Common Name field of a Certificate Signing Request (CSR) created by LoadMaster. With this release, LoadMaster uses the UTF8STRING string type for the Common Name.
PD-17612 Licensing: Fixed an issue with licensed bandwidth limits where Virtual Services with SubVSs would be prematurely limited.
PD-17504 SSL: Fixed an issue that caused SSL handshakes to fail between LoadMaster and a Real Server with certain types of EC certificates.
PD-17308 Body Response Content Rules: If a user adds a body response rule to a Nested/Cascaded Virtual Service the LoadMaster removes all "Set-Cookie" headers. This bug has been fixed.
PD-17207 API: Using the killsession API to end an SSO session results in an overflow error. This issue has been fixed.
PD-16707 SSO: Steering Groups: Fixed an issue where a user would close the browser and get an error logging into the application again using a steering group.
PD-16495 GEO: Fixed an issue where adding an IP address of to an FQDN caused issues. Now, is blocked from being added to an FQDN.
PD-16113 GEO: LoadMaster adds the Global TTL to TXT records when local settings are enabled on the FQDN. This issue has been fixed; now, the Local TTL is added when local settings are enabled.
PD-15396 GEO: Fixed an issue that caused LM to send a spurious "KEMP GEO" TXT record in DNS responses, if the TXT record field is empty and the queried FQDN is not a sub-domain of the ZoneName.

New Known Issues

PD-18467 Mobile ActiveSync User Single Sign On: Mobile Devices using ActiveSync are denied access when using Principal Name (e.g., to log in. The workaround is to use Username instead (e.g., company\name).
PD-18099 Client Certificates: Authentication may be denied if multiple "Other names" are present in the client certificate.
PD-18028 Client Certificates: Under certain circumstances, a user with a valid certificate is incorrectly denied access; adding the email address of the user to the CN field causes login to succeed.
PD-18021 Content Rule UI: Display is incorrect when the 'Ignore case' option is enabled.
PD-17934 Client Limiting: An internal error can cause client limiting to be incorrectly applied; e.g., log messages may indicate that limiting is being applied, removed, and applied again within a period of time that is shorter than the period set by the user.
PD-17933 ESP: When ESP sends data, it sets the Set-Cookie header without a samesite parameter, which causes some browsers to interpret this as "samesite=lax" and possibly refuse to deliver content.
PD-17927 LDAP UI Access: Under certain circumstances, a user that has no LDAP credentials can gain access to the UI.
PD-17867 Historical Graphs: Under certain circumstances, graphs for VLANs and Bonded Interfaces may no longer appear in the UI after upgrade to 7.2.53.
PD-16140 GEO Clustering Mode: TXT records are blank after 1024 IP addresses are added to an FQDN.

Existing Known Issues

The following issues appeared in the Release Notes for the previous release of LMOS.

PD-15872 LDAP/Syslog: StartTLS is not working when the Server Certificate Validation flag is enabled.
PD-15633 GEO: If you add a Zone Name to GEO after you have created working FQDNs, GEO may no longer respond to queries for one or more of the FQDN safter the Zone Name is added. The workaround is to remove and then re-add the FQDNs that are no longer working.
PD-15475 VS Redirects: If you attempt to upload a new redirect error HTML file to a Virtual Service with Not Available Redirection Handling enabled while traffic is currently being redirected, then traffic to the VS is dropped. Click the Error Message radio button in the UI and the VS begins accepting connections again.
PD-15354 SSO Timeout: In LMOS, a fix was introduced for issues that caused an SSO client to not be properly logged out when the configured session timeout expires. It has been observed that while sessions do timeout, they are not always closed immediately upon the expiry of the timer; it can take close to a minute longer for the session to actually be closed.
PD-15294 ESP Verify Bearer Header: LoadMaster does not return an error when an encrypted token is received and there is no SSL certificate assigned to the VS to decrypt the token.
PD-15172 ESP Verify Bearer Header: Validation is not working when "Allowed Virtual Hosts" and "Allowed Virtual Directories" are blank on the Virtual Service.
PD-14943 Single Sign On: When Form Based Authentication is enabled on the server side, it is possible that after filling out correct credentials and submitting the login form, the form will be presented again; once the second login form is submitted with correct credentials, the login succeeds.
PD-13899 ACLs and Real Servers: Real Servers located on networks on which LoadMaster also has an IP address are always allowed to access Virtual Services configured to use ports 22 (SSH), 25 (SMTP), 53 (DNS), 161 (SNMP), and 443(UI). Any access control list (ACL) settings on LoadMaster will be ignored for these Real Servers. For Layer 7 services, this issue can be worked around using Content Rules. The only workaround for other services is to block access for local Real Servers (if desired) on another network device (firewall, switch, router, etc.).
PD-12838 ESP / SSO: The ESP Permitted Group SID(s) setting is not working as expected when configured on a SubVS.
PD-12616 WAF / Compression: With Web Application Firewall (WAF) enabled, compressed files are incorrectly decompressed. As a workaround, ensure compression is enabled in VS Advanced Properties by selecting the Enable Compression option.
PD-12492 Downgrade: If an Azure VLM is downgraded to the LTS firmware release (7.1.35.x), the WUI may display in the top right-hand corner that the VLM is a Hyper-V VLM. This indicates that the Azure VLM Add-On Package must be added to the system to provide full Azure VLM functionality. If this occurs, please contact Kemp Support to get the required add-on package.
Hardware Support: The LoadMaster models LM-X15, LM-X25, and LM-X40 do not support the following SFP+ modules: LM-SFP-SX (SFP+ SX Transceiver 1000BASE-SX 850nm, 550m over MMF), LM-SFP-LX (SFP+ LX Transceiver 1000BASE-LX 1310nm, 10KM over SMF).
PD-12237 HA / NTP: Configuring NTP for the first time after the system is running in High Availability (HA) mode and when the current time on the machines is not correct, may cause the systems to both go into the Master state.
PD-12147 ESP / RADIUS: In a LoadMaster configuration with ESP and Radius server-side authentication enabled, sessions may fail to be established.
PD-12058 Browser Support: An issue exists when connecting to the LoadMaster WUI when using newer versions of the Firefox browser on initial configuration of a hardware FIPS LoadMaster.
PD-11861 RADIUS / IPv6: IPv6 is not supported by the current RADIUS implementation in the LoadMaster for both WUI Authorization and ESP Authentication.
PD-11166 Networking: Azure LoadMasters are not translating the additional network address between the Master and Slave correctly.
PD-11044 SharePoint Virtual Services: A second authentication prompt is presented when a file is uploaded to SharePoint with the following configuration: WAF is configured with Process Responses enabled on the main Virtual Service and KCD is enabled on the SubVS level for server-side authentication.
PD-10917 HA: An issue exists when setting up a 2-armed HA Virtual LoadMaster in Azure.
PD-10784 HA: Configuring LoadMaster HA using eth1 on an Amazon Web Services (AWS) Virtual LoadMaster does not work.
PD-10586 GEO: If a GEO FQDN is configured with All Available as the Selection Criteria, IP addresses are returned even if the cluster is disabled.
PD-10490 Content Rules: The vsremovewafrule RESTful API command does not allow multiple rules to be removed.
PD-10474 Intrusion Detection: A SNORT rule is triggering a false positive in certain scenarios.
PD-10193 Exchange 2010 Virtual Services: A WAF, ESP, and KCD configuration with Microsoft Exchange 2010 is not supported.
PD-10188 Browser Support: (Safari) When adding a Real Server to a Virtual Service or SubVS using the Safari browser, the list of available Real Servers is not available.
PD-10159 Statistics: When upgrading firmware from version 7.1.35.n, CPU and network usage graphs are not appearing. As a workaround, reset the statistics in the WUI.
PD-10136 Clustering: In a LoadMaster cluster configuration, a new node can be added with the same IP address as an existing node.
WAF: There is an API command to list individual rules in a ruleset, but there is no command to list the available rulesets themselves.
PD-9765 GEO: DNS TCP requests from unknown sources are not supported.
PD-9507 Networking: Unable to add an SDN controller using the RESTful API/WUI in a specific scenario.
PD-9375 SharePoint Virtual Services: Microsoft Office files in SharePoint do not work in Firefox and Chrome when using SAML authentication.