Here http://pubs.vmware.com/vsphere-6-5/index.jsp?topic=%2Fcom.vmware.wssdk.apiref.doc%2Fvim.vm.GuestOsDescriptor.GuestOsIdentifier.html you can find the Guest OS list with guest name and guest id.
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You can go to FTP of your WHMCS and go to this location WHMCS/modules/addons/vmware/guestOs/ and edit the file guestOsIdentifier.txt in editor. In this file you can add the more OS.
Copy the OS version and version id from given link and paste in this guestOsIdentifier.txt file according to OS family like (Windows/Linux/Others).
Instructions for add new OS
Format like "OS Family-OS Version-OS Version ID". Add all values with hyphen (-) separator.
Examples are given below:
- For Windows "Windows-Windows 7-windows7Guest"
- For Linux "Linux-Ubuntu Linux-ubuntuGuest"
- For Others "Others-FreeBSD-freebsdGuest"
| asianux3_64Guest | Asianux Server 3 (64 bit) Since vSphere API 4.0 |
| asianux3Guest | Asianux Server 3 (64 bit)Since vSphere API 4.0 |
| asianux3Guest | Asianux Server 3 Since vSphere API 4.0 |
| asianux4_64Guest | Asianux Server 4 (64 bit)Since vSphere API 4.0 |
| asianux4Guest | Asianux Server 4 Since vSphere API 4.0 |
| asianux5_64Guest | Asianux Server 5 (64 bit)Since vSphere API 6.0 |
| asianux7_64Guest | Asianux Server 7 (64 bit) Since vSphere API 6.5 |
| centos6_64Guest | CentOS 6 (64-bit) Since vSphere API 6.5 |
| centos64Guest | CentOS 4/5 (64-bit) Since vSphere API 4.1 |
| centos6Guest | CentOS 6 Since vSphere API 6.5 |
| centos7_64Guest | CentOS 7 (64-bit) Since vSphere API 6.5 |
| centos7Guest | CentOS 7 Since vSphere API 6.5 |
| centosGuest | CentOS 4/5 Since vSphere API 4.1 |
| coreos64Guest | CoreOS Linux (64 bit) Since vSphere API 6.0 |
| darwin10_64Guest | Mac OS 10.6 (64 bit) Since vSphere API 5.0 |
| darwin10Guest | Mac OS 10.6 Since vSphere API 5.0 |
| darwin11_64Guest | Mac OS 10.7 (64 bit) Since vSphere API 5.0 |
| darwin11Guest | Mac OS 10.7 Since vSphere API 5.0 |
| darwin12_64Guest | Mac OS 10.8 (64 bit) Since vSphere API 5.5 |
| darwin13_64Guest | Mac OS 10.9 (64 bit) Since vSphere API 5.5 |
| darwin14_64Guest | Mac OS 10.10 (64 bit) Since vSphere API 6.0 |
| darwin15_64Guest | Mac OS 10.11 (64 bit) Since vSphere API 6.5 |
| darwin16_64Guest | Mac OS 10.12 (64 bit) Since vSphere API 6.5 |
| darwin64Guest | Mac OS 10.5 (64 bit) Since vSphere API 4.0 |
| darwinGuest | Mac OS 10.5 |
| debian10_64Guest | Debian GNU/Linux 10 (64 bit) Since vSphere API 6.5 |
| debian10Guest | Debian GNU/Linux 10 Since vSphere API 6.5 |
| debian4_64Guest | Debian GNU/Linux 4 (64 bit) Since vSphere API 4.0 |
| debian4Guest | Debian GNU/Linux 4 Since vSphere API 4.0 |
| debian5_64Guest | Debian GNU/Linux 5 (64 bit) Since vSphere API 4.0 |
| debian5Guest | Debian GNU/Linux 5 Since vSphere API 4.0 |
| debian6_64Guest | Debian GNU/Linux 6 (64 bit) Since vSphere API 5.0 |
| debian6Guest | Debian GNU/Linux 6 Since vSphere API 5.0 |
| debian7_64Guest | Debian GNU/Linux 7 (64 bit) Since vSphere API 5.5 |
| debian7Guest | Debian GNU/Linux 7 Since vSphere API 5.5 |
| debian8_64Guest | Debian GNU/Linux 8 (64 bit) Since vSphere API 6.0 |
| debian8Guest | Debian GNU/Linux 8 Since vSphere API 6.0 |
| debian9_64Guest | Debian GNU/Linux 9 (64 bit) Since vSphere API 6.5 |
| debian9Guest | Debian GNU/Linux 9 Since vSphere API 6.5 |
| dosGuest | MS-DOS. |
| eComStation2Guest | eComStation 2.0 Since vSphere API 5.0 |
| eComStationGuest | eComStation 1.x Since vSphere API 4.1 |
| fedora64Guest | Fedora Linux (64 bit) Since vSphere API 5.1 |
| fedoraGuest | Fedora Linux Since vSphere API 5.1 |
| freebsd64Guest | FreeBSD x64 |
| freebsdGuest | FreeBSD |
| genericLinuxGuest | Other Linux Since vSphere API 5.5 |
| mandrakeGuest | Mandrake Linux Since vSphere API 5.5 |
| mandriva64Guest | Mandriva Linux (64 bit) Since vSphere API 4.0 |
| mandrivaGuest | Mandriva Linux Since vSphere API 4.0 |
| netware4Guest | Novell NetWare 4 |
| netware5Guest | Novell NetWare 5.1 |
| netware6Guest | Novell NetWare 6.x |
| nld9Guest | Novell Linux Desktop 9 |
| oesGuest | Open Enterprise Server |
| openServer5Guest | SCO OpenServer 5 Since vSphere API 4.0 |
| openServer6Guest | SCO OpenServer 6 Since vSphere API 4.0 |
| opensuse64Guest | OpenSUSE Linux (64 bit) Since vSphere API 5.1 |
| opensuseGuest | OpenSUSE Linux Since vSphere API 5.1 |
| oracleLinux6_64Guest | Oracle 6 (64-bit) Since vSphere API 6.5 |
| oracleLinux64Guest | Oracle Linux 4/5 (64-bit) Since vSphere API 4.1 |
| oracleLinux6Guest | Oracle 6 Since vSphere API 6.5 |
| oracleLinux7_64Guest | Oracle 7 (64-bit) Since vSphere API 6.5 |
| oracleLinux7Guest | Oracle 7 Since vSphere API 6.5 |
| oracleLinuxGuest | Oracle Linux 4/5 Since vSphere API 4.1 |
| os2Guest | OS/2 |
| other24xLinux64Guest | Linux 2.4x Kernel (64 bit) (experimental) |
| other24xLinuxGuest | Linux 2.4x Kernel |
| other26xLinux64Guest | Linux 2.6x Kernel (64 bit) (experimental) |
| other26xLinuxGuest | Linux 2.6x Kernel |
| other3xLinux64Guest | Linux 3.x Kernel (64 bit) Since vSphere API 5.5 |
| other3xLinuxGuest | Linux 3.x Kernel Since vSphere API 5.5 |
| otherGuest | Other Operating System |
| otherGuest64 | Other Operating System (64 bit) (experimental) |
| otherLinux64Guest | Linux (64 bit) (experimental) |
| otherLinuxGuest | Linux 2.2x Kernel |
| redhatGuest | Red Hat Linux 2.1 |
| rhel2Guest | Red Hat Enterprise Linux 2 |
| rhel3_64Guest | Red Hat Enterprise Linux 3 (64 bit) |
| rhel3Guest | Red Hat Enterprise Linux 3 |
| rhel4_64Guest | Red Hat Enterprise Linux 4 (64 bit) |
| rhel4Guest | Red Hat Enterprise Linux 4 |
| rhel5_64Guest | Red Hat Enterprise Linux 5 (64 bit) (experimental) Since VI API 2.5 |
| rhel5Guest | Red Hat Enterprise Linux 5 Since VI API 2.5 |
| rhel6_64Guest | Red Hat Enterprise Linux 6 (64 bit) Since vSphere API 4.0 |
| rhel6Guest | Red Hat Enterprise Linux 6 Since vSphere API 4.0 |
| rhel7_64Guest | Red Hat Enterprise Linux 7 (64 bit) Since vSphere API 5.5 |
| rhel7Guest | Red Hat Enterprise Linux 7 Since vSphere API 5.5 |
| sjdsGuest | Sun Java Desktop System |
| sles10_64Guest | Suse Linux Enterprise Server 10 (64 bit) (experimental) Since VI API 2.5 |
| sles10Guest | Suse linux Enterprise Server 10 Since VI API 2.5 |
| sles11_64Guest | Suse Linux Enterprise Server 11 (64 bit) Since vSphere API 4.0 |
| sles11Guest | Suse linux Enterprise Server 11 Since vSphere API 4.0 |
| sles12_64Guest | Suse Linux Enterprise Server 12 (64 bit) Since vSphere API 5.5 |
| sles12Guest | Suse linux Enterprise Server 12 Since vSphere API 5.5 |
| sles64Guest | Suse Linux Enterprise Server 9 (64 bit) |
| slesGuest | Suse Linux Enterprise Server 9 |
| solaris10_64Guest | Solaris 10 (64 bit) (experimental) |
| solaris10Guest | Solaris 10 (32 bit) (experimental) |
| solaris11_64Guest | Solaris 11 (64 bit) Since vSphere API 5.0 |
| solaris6Guest | Solaris 6 |
| solaris7Guest | Solaris 7 |
| solaris8Guest | Solaris 8 |
| solaris9Guest | Solaris 9 |
| suse64Guest | Suse Linux (64 bit) |
| suseGuest | Suse Linux |
| turboLinux64Guest | Turbolinux (64 bit) Since vSphere API 4.0 |
| turboLinuxGuest | Turbolinux |
| ubuntu64Guest | Ubuntu Linux (64 bit) |
| ubuntuGuest | Ubuntu Linux |
| unixWare7Guest | SCO UnixWare 7 |
| Since vSphere API 4.0 | |
| vmkernel5Guest | VMware ESX 5 Since vSphere API 5.0 |
| vmkernel65Guest | VMware ESX 6.5 Since vSphere API 6.5 |
| vmkernel6Guest | VMware ESX 6 Since vSphere API 6.0 |
| vmkernelGuest | VMware ESX 4 Since vSphere API 5.0 |
| vmwarePhoton64Guest | VMware Photon (64 bit) Since vSphere API 6.5 |
| win2000AdvServGuest | Windows 2000 Advanced Server |
| win2000ProGuest | Windows 2000 Professional |
| win2000ServGuest | Windows 2000 Server |
| win31Guest | Windows 3.1 |
| win95Guest | Windows 95 |
| win98Guest | Windows 98 |
| windows7_64Guest | Windows 7 (64 bit) Since vSphere API 4.0 |
| windows7Guest | Windows 7 Since vSphere API 4.0 |
| windows7Server64Guest | Windows Server 2008 R2 (64 bit) Since vSphere API 4.0 |
| windows8_64Guest | Windows 8 (64 bit) Since vSphere API 5.0 |
| windows8Guest | Windows 8 Since vSphere API 5.0 |
| windows8Server64Guest | Windows 8 Server (64 bit) Since vSphere API 5.0 |
| windows9_64Guest | Windows 10 (64 bit) Since vSphere API 6.0 |
| windows9Guest | Windows 10 Since vSphere API 6.0 |
| windows9Server64Guest | Windows 10 Server (64 bit) Since vSphere API 6.0 |
| windowsHyperVGuest | Windows Hyper-V Since vSphere API 5.5 |
| winLonghorn64Guest | Windows Longhorn (64 bit) (experimental) Since VI API 2.5 |
| winLonghornGuest | Windows Longhorn (experimental) Since VI API 2.5 |
| winMeGuest | Windows Millenium Edition |
| winNetBusinessGuest | Windows Small Business Server 2003 |
| winNetDatacenter64Guest | Windows Server 2003, Datacenter Edition (64 bit) (experimental) Since VI API 2.5 |
| winNetDatacenterGuest | Windows Server 2003, Datacenter Edition Since VI API 2.5 |
| winNetEnterprise64Guest | Windows Server 2003, Enterprise Edition (64 bit) |
| winNetEnterpriseGuest | Windows Server 2003, Enterprise Edition |
| winNetStandard64Guest | Windows Server 2003, Standard Edition (64 bit) |
| winNetStandardGuest | Windows Server 2003, Standard Edition |
| winNetWebGuest | Windows Server 2003, Web Edition |
| winNTGuest | Windows NT 4 |
| winVista64Guest | Windows Vista (64 bit) |
| winVistaGuest | Windows Vista |
| winXPHomeGuest | Windows XP Home Edition |
| winXPPro64Guest | Windows XP Professional Edition (64 bit) |
| winXPProGuest | Windows XP Professional |