Troubleshooting Cisco AnyConnect: Rejected Connection Request

NetCraftsmen®

The Cisco AnyConnect VPN client is Cisco’s SSL VPN client offering.  Cisco currently supports this VPN client and the legacy IPSec VPN client, called the Cisco VPN Client.  The Cisco VPN client will be phased out over time.  This can be seen by the Cisco VPN Client FAQ explaining that 64 bit operating systems are not supported by the Cisco VPN client, but are supported by the Cisco AnyConnect VPN client. 

With this in mind, it’s important to understand possible scenarios where the AnyConnect VPN client could break.  One scenario is shown below.  In this scenario, the AnyConnect VPN client works for all users except for one user.  This user had the AnyConnect VPN client working for period of time, but found that it didn’t work one day.  The error message that the user sees is shown below.

 

Since other users can connect to the network, through the AnyConnect VPN client, the problem can be narrowed down to something on the user’s computer.  The user is using the correct VPN settings.  In fact, the error message shows up after successful authentication.  There do not seem to be any other settings, within the AnyConnect VPN client, that could be modified to fix the problem.

The key to understanding the problem is recognizing that the AnyConnect VPN client uses SSL.  In addition to the client settings, the Microsoft Internet Explorer settings need to be taken into account.  For this particular problem, the web proxy settings were set.  This caused the failure shown above.  In order to get around this, the VPN server IP address, must be added to the “Exceptions” list.  This is shown below.

 

After adding the VPN server IP address to the “Exceptions” list, the AnyConnect VPN client connects successfully.  In general, this example serves as a reminder to look at the Microsoft Internet Explorer settings when troubleshooting AnyConnect VPN client connectivity problems.

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Nick Kelly

Cybersecurity Engineer, Cisco

Nick has over 20 years of experience in Security Operations and Security Sales. He is an avid student of cybersecurity and regularly engages with the Infosec community at events like BSides, RVASec, Derbycon and more. The son of an FBI forensics director, Nick holds a B.S. in Criminal Justice and is one of Cisco’s Fire Jumper Elite members. When he’s not working, he writes cyberpunk and punches aliens on his Playstation.

 

Virgilio “BONG” dela Cruz Jr.

CCDP, CCNA V, CCNP, Cisco IPS Express Security for AM/EE
Field Solutions Architect, Tech Data

Virgilio “Bong” has sixteen years of professional experience in IT industry from academe, technical and customer support, pre-sales, post sales, project management, training and enablement. He has worked in Cisco Technical Assistance Center (TAC) as a member of the WAN and LAN Switching team. Bong now works for Tech Data as the Field Solutions Architect with a focus on Cisco Security and holds a few Cisco certifications including Fire Jumper Elite.

 

John Cavanaugh

CCIE #1066, CCDE #20070002, CCAr
Chief Technology Officer, Practice Lead Security Services, NetCraftsmen

John is our CTO and the practice lead for a talented team of consultants focused on designing and delivering scalable and secure infrastructure solutions to customers across multiple industry verticals and technologies. Previously he has held several positions including Executive Director/Chief Architect for Global Network Services at JPMorgan Chase. In that capacity, he led a team managing network architecture and services.  Prior to his role at JPMorgan Chase, John was a Distinguished Engineer at Cisco working across a number of verticals including Higher Education, Finance, Retail, Government, and Health Care.

He is an expert in working with groups to identify business needs, and align technology strategies to enable business strategies, building in agility and scalability to allow for future changes. John is experienced in the architecture and design of highly available, secure, network infrastructure and data centers, and has worked on projects worldwide. He has worked in both the business and regulatory environments for the design and deployment of complex IT infrastructures.