Hi All ,
Any one using Cisco VPN Client [vpnclient-linux-4.6.00.0045-k9.tar.gz] on CentOS 5 [2.6.18-53.1.4.el5-i686]
The client installation is giving error for making module "cisco_ipsec.ko".
Can any one help me out to resolve this :

The whole stack trace of the installation after the extraction of the tar is as shown:
[root@XBox vpnclient]# ./vpn_install
Cisco Systems VPN Client Version 4.6.00 (0045) Linux Installer
Copyright (C) 1998-2004 Cisco Systems, Inc. All Rights Reserved.

By installing this product you agree that you have read the
license.txt file (The VPN Client license) and will comply with
its terms.
Directory where binaries will be installed [/usr/local/bin]
Automatically start the VPN service at boot time [yes]
In order to build the VPN kernel module, you must have the
kernel headers for the version of the kernel you are running.
Directory containing linux kernel source code [/lib/modules/2.6.18-53.1.4.el5/build]
* Binaries will be installed in "/usr/local/bin".
* Modules will be installed in "/lib/modules/2.6.18-53.1.4.el5/CiscoVPN".
* The VPN service will be started AUTOMATICALLY at boot time.
* Kernel source from "/lib/modules/2.6.18-53.1.4.el5/build" will be used to build the module.
Is the above correct [y]
Making module
make -C /lib/modules/2.6.18-53.1.4.el5/build SUBDIRS=/home/saurabh/software/vpnclient modules
make[1]: Entering directory `/usr/src/kernels/2.6.18-53.1.4.el5-i686'
  CC [M]  /home/saurabh/software/vpnclient/linuxcniapi.o
In file included from /home/saurabh/software/vpnclient/linuxcniapi.c:12:
include/linux/config.h:6:2: warning: #warning Including config.h is deprecated.
/home/user1/software/vpnclient/linuxcniapi.c: In function ‘CniInjectReceive’:
/home/user1/software/vpnclient/linuxcniapi.c:315: error: ‘struct sk_buff’ has no member named ‘stamp’
/home/user1/software/vpnclient/linuxcniapi.c: In function ‘CniInjectSend’:
/home/user1/software/vpnclient/linuxcniapi.c:452: error: ‘struct sk_buff’ has no member named ‘stamp’
make[2]: *** [/home/user1/software/vpnclient/linuxcniapi.o] Error 1
make[1]: *** [_module_/home/user1/software/vpnclient] Error 2
make[1]: Leaving directory `/usr/src/kernels/2.6.18-53.1.4.el5-i686'
make: *** [default] Error 2
Failed to make module "cisco_ipsec.ko".

Thanks & Regards
Saurabh