Synopsys Common Licensing (SCL) is the licence server package that Synopsys uses to serve keys for its tools. The Licensing QuickStart describes it as based on FlexNet: SCL 2025.03, 2025.03-SP1 and 2025.03-SP2 use FlexNet 11.19.7 for lmgrd, snpslmd, lmstat and the other utilities, and SCL 2025.03-SP2 is recommended for all customers.[1] It uses a combined vendor daemon, snpslmd, so one daemon and one licence file serve many products that previously had their own daemons.[1] For a software asset manager the licence server is the place where entitlement is enforced and evidence of use is produced, and the rules for editing, moving and verifying key files are therefore compliance controls.
Getting keys and software
Keys come from SmartKeys on SolvNetPlus, selected by Site ID. The Site ID appears in the site_info file in the tool tree or near the top of an old key file, in the line “Site Id” of the SYNOPSYS INC. KEY CERTIFICATE header.[1] SmartKeys processes a request and sends the key file by e-mail.[1] Keys for Flexible Spending Account orders follow the same route: once an order is placed in the Customer Self Service site, keys are generated and the ordering user is e-mailed that they can be downloaded from the self-retrieval site, after which any SolvNetPlus user registered for the Site ID can download them.[6] Entitled customers download SCL from the SolvNetPlus Download Center, and Linux users also need the separate Synopsys Installer.[1]
SCL versions track key versions. SCL 2025.03 or higher is required for new licence files issued on or after March 7, 2024, which reference the snpslmd daemon and the Valtrix daemons; SCL 2025.03 and later will not start unless the legacy VALTRIXT daemon is first shut down, and keys that reference VALTRIXT are not compatible with SCL on Windows and must be hosted on a supported Linux distribution.[1] SCL for Windows also does not support keys that reference several legacy daemons, including doradod, fishtail and sftlmd.[1] An upgrade of the licence server is therefore often forced by a new key file and not only by a new tool release.
The key file
A key file as received contains a SERVER line (host name, hostid, port), a VENDOR line for snpslmd, an SSS key, and INCREMENT lines, one per feature, each with a version, an expiration date, a quantity, and fields such as ISSUED, START, a serial number and an authorisation code.[1] Synopsys sets firm limits on editing:
- Only the SERVER and VENDOR lines may be modified. “DO NOT add, remove or modify any INCREMENT lines within the license file. Doing so will invalidate your licenses.”[4]
- The USE_SERVER keyword must stay, on a line by itself before any cvd-format INCREMENT lines. Remove VENDOR or DAEMON lines for non-snpslmd vendor daemons; “these are not allowed.”[1]
- On the SERVER line the host name must match the output of the hostname command, and the hostid is not to be changed. The port may be any available TCP port between 1024 and 64000, with 27000 to 27009 not supported for the lmgrd port; the Synopsys default is 27020.[1]
- The VENDOR line must give the full path to snpslmd and may add a path to an options file, and a vendor daemon port can be fixed on that line.[1]
The checklist requires verification with the sssverify utility every time a file is changed in any way, using the version shipped with the most recently installed SCL. Regular revenue keys must have a valid SSS key, temporary keys need an SSST feature, and a file with removed features fails the fingerprint check.[4] Temporary keys can be appended to a revenue file after removing duplicate SERVER, VENDOR and USE_SERVER lines, but “temporary keys can be voided by duplicate production keys with a later ISSUED date”, so Synopsys recommends keeping them on a separate server.[4]
Hostids and rehosting
The hostid in the SERVER line must match the licence server; for physical machines it is a 12-character value from the lmhostid command and should correspond to a physical device such as an Ethernet card.[2] Synopsys states that “you must not modify the key file hostid as it is encrypted into every key.” If the hostid is wrong the customer contacts its Synopsys Account Manager for a new file, and where no Synopsys error was made a rehost form may be required. Only on-support keys may be rehosted.[1] The dongle page repeats the point: “Off-support licenses cannot be rehosted.”[3] A licence server migration is therefore a commercial request as well as a technical task, and a customer whose maintenance has lapsed may be unable to move its keys.
Cloud and virtual machines
For cloud machines the Ethernet address is not acceptable. The FNLS (FlexNet Publisher Licensing Service) cloud service included with SCL must be running, and the hostid is then VM_UUID, obtained with lmhostid -ptype VM -uuid for all clouds, or the AWS elastic IP hostid, from lmhostid -ptype AMZN -eip, for AWS only.[2] Redundant licence servers, a triad with three SERVER lines and PRIMARY_IS_MASTER on the master, are “supported only for non-cloud machines”.[1] The QuickStart also requires FNLS to be running before SCL starts and states that SCL 2025.03 and later allow the server to run with root or sudo privileges on Linux.[1]
Dongles
Dongle-based licences are supported for specific tools only, such as HSPICE or Synplify Pro, on Windows and Linux x86_64 and on physical machines, and the hostid is a FLEXID value printed on the device.[2] Synopsys recommends FLEXID 10 WibuKey dongles purchased from Revenera, supports up to three per machine, and will in some cases supply a dongle for new HSPICE orders.[3] “Except for maintenance renewals, orders are no longer accepted for licenses for Rainbow/Sentinel USB dongles (FLEXID=7-) or Dallas (FLEXID=8-) parallel port dongles.” Revenera “does not recommend using FLEXID (dongle) hostids” for licence servers running in virtual machines.[3] Counted dongle licences need SCL, while uncounted, serverless licences do not.[3]
Starting the server and how clients find it
SCL is started with lmgrd and the key file, and the debug log should show the FlexNet version, the SCL version, no SSS errors (“Invalid license file fingerprint”) and the expected list of features.[1] All legacy vendor daemons must be shut down first.[1] Each user account sets a licensing variable: “SNPSLMD_LICENSE_FILE is preferred over LM_LICENSE_FILE”, with port@host values; several servers are separated by a colon on Linux and a semicolon on Windows, and triple redundant servers by commas.[1] For counting, the SCL log lists features served and the licence server can be queried with standard FlexNet tools, but the contract limits on Use Area and Clients apply regardless of how the server is configured.
Ansys Semiconductor
From December 7, 2026 the licence file format of Ansys Semiconductor licences is scheduled to change to the Synopsys CVD format compatible only with snpslmd, requiring SCL 2026.12 or later; the details are in the Synopsys and Ansys licensing transition article.[5]
Out of scope
This article does not cover the SCL Administration Guide, which requires a SolvNet login, option file syntax, borrowing, or the contractual consequences of altering a key file.