Enabling single sign-on authentication for accessing protected network services

A Virtual Private Network (VPN) server, comprising:

• a memory;
• and
• a processing device, operatively coupled to the memory, the processing device to:
• receive a login information associated with a an authentication server;
• transmit an authentication request on behalf of a client to the authentication server;
• receive an authentication ticket responsive to the authentication request, wherein the authentication ticket is encrypted using a secret key shared by the VPN server and the authentication server, and wherein the secret key is not shared with the client;
• provide the authentication ticket to the client;
• receive, from the client, a service request comprising the authentication ticket and a request to access a service residing on a protected network associated with the VPN server;
• responsive to detecting that a number of authentication requests received from the client exceeds a threshold number, deny the request to access the service;
• and
• responsive to successfully authenticating the client presenting the authentication ticket, transmit, to the service, a service access request comprising the authentication ticket.

A non-transitory computer-readable storage medium comprising executable instructions that, when executed by a processing device of a Virtual Private Network (VPN) server, cause the processing device to:

• receive a login information associated with an authentication server;
• transmit an authentication request on behalf of a client to the authentication server, wherein the authentication ticket is encrypted using a secret key shared by the VPN server and the authentication server, and wherein the secret key is not shared with the client;
• provide the authentication ticket to the client;
• receive, from the client, a service request comprising the authentication ticket and a request to access a service residing on a protected network associated with the VPN server;
• responsive to detecting that a number of authentication requests received from the client exceeds a threshold number, deny the request to access the service;
• and
• responsive to successfully authenticating the client presenting the authentication ticket, transmit, to the service, a service access request comprising the authentication ticket.