You may get following error (shown in blue) in your VPN Client LOG, while connecting through Cisco VPN Client to PIX Firewall, which is configured to allow VPN Connections for Remote Access.
Cisco Systems VPN Client Version 5.0.07.0440
Copyright (C) 1998-2010 Cisco Systems, Inc. All Rights Reserved.
Client Type(s): Windows, WinNT
Running on: 6.1.7601 Service Pack 1
Config file directory: C:\Program Files (x86)\Cisco Systems\VPN Client\
Copyright (C) 1998-2010 Cisco Systems, Inc. All Rights Reserved.
Client Type(s): Windows, WinNT
Running on: 6.1.7601 Service Pack 1
Config file directory: C:\Program Files (x86)\Cisco Systems\VPN Client\
1 11:42:49.467 07/30/13 Sev=Warning/2 IKE/0xE300009B
Invalid SPI size (PayloadNotify:116)
Invalid SPI size (PayloadNotify:116)
2 11:42:49.467 07/30/13 Sev=Warning/3 IKE/0xA3000058
Received malformed message or negotiation no longer active (message id: 0x00000000)
Received malformed message or negotiation no longer active (message id: 0x00000000)
3 11:42:54.863 07/30/13 Sev=Warning/2 IKE/0xE300009B
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
4 11:42:54.864 07/30/13 Sev=Warning/2 IKE/0xE300009B
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
5 11:42:59.943 07/30/13 Sev=Warning/2 IKE/0xE300009B
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
6 11:42:59.944 07/30/13 Sev=Warning/2 IKE/0xE300009B
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
7 11:43:05.022 07/30/13 Sev=Warning/2 IKE/0xE300009B
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
8 11:43:05.023 07/30/13 Sev=Warning/2 IKE/0xE300009B
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Fragmented msg rcvd with no associated SA (PacketReceiver:133)
Solution
Cisco had dropped support for DES with the 4.0(2) VPN client’s release. So the VPN Client doesn’t support combination of cipher/hash (in this case, DES/SHA1)
But the VPN Client continues to support DES/MD5. However, support for DES/SHA is no longer available, and Release 3.7 and later VPN Clients cannot connect to any central-site device group that is configured for (or proposing) DES/SHA. The VPN Client must either connect to a different group or the system administrator for the central-site device must change the configuration from DES/SHA to DES/MD5 or another supported configuration.
