Cisco VPN Client na Slackware

Por questões de segurança, principalmente numa rede de computadores onde haja muitos servidores, roteadores, estações e dispositivos suscetíveis à interceptação de informações, adota-se ferramentas de segurança para que possa obter uma melhor integridade dos dados. Com base nessa necessidade, iremos instalar e configurar o Cisco VPN Client para acesso através de um estação.

O que é VPN?

Traduzindo, rede privada virtual.
Conceituando, a VPN é uma implementação de segurança que utiliza criptografia e tunelamento de dados para a criação de um canal virtual entre dois pontos distintos. Funciona sobre a rede pública (Internet).

Vantagens
- Canal dedicado
- Canal privado
- Criptografia

Protocolos
- PPTP (Point-to-Point Tunneling Protocol)
- NAT (Network Address Translator)
- L2TP (Layer 2 Tunneling Protocol)
- L2TP/IPSec

Vamos ao que interessa...

Efetue o download do aplicativo, conforme o comando abaixo. O ideal é que seja instalada a versão mais recente. Neste link, a versão está atualizada (de acordo com a data de publicação desse pequeno tutorial) com as correções no instalador para os kernels 2.6.24 à superiores.

1) Iniciando o download...

root@spinho:~# wget -c http://www.lan.kth.se/vpn/bin/vpnclient-linux-x86_64-4.8.02.0030-k9.tar.gz&

2) Após ter “baixado” o arquivo, descompacte-o para que seja possível instalá-lo...

root@spinho:~# tar xvf vpnclient-linux-x86_64-4.8.02.0030-k9.tar.gz

Será visualizado...
vpnclient/
vpnclient/libvpnapi.so
vpnclient/vpnapi.h
vpnclient/cisco_cert_mgr
vpnclient/vpnclient
vpnclient/ipseclog
vpnclient/cvpnd
vpnclient/vpn_install
vpnclient/vpnclient_init
vpnclient/vpn_uninstall
vpnclient/driver_build.sh
vpnclient/sample.pcf
vpnclient/vpnclient.ini
vpnclient/license.txt
vpnclient/license.rtf
vpnclient/interceptor.c
vpnclient/linuxcniapi.c
vpnclient/linuxcniapi.h
vpnclient/vpn_ioctl_linux.h
vpnclient/IPSecDrvOS_linux.c
vpnclient/linux_os.h
vpnclient/frag.h
vpnclient/frag.c
vpnclient/linuxkernelapi.c
vpnclient/GenDefs.h
vpnclient/mtu.h
vpnclient/IPSecDrvOSFunctions.h
vpnclient/IPSecDrvOS_linux.h
vpnclient/Cniapi.h
vpnclient/unixcniapi.h
vpnclient/unixkernelapi.h
vpnclient/config.h
vpnclient/libdriver64.so
vpnclient/libdriver.so
vpnclient/Makefile

3) Acessando o diretório com os binários...

root@spinho:~# cd vpnclient

4) Instalando o aplicativo...

root@spinho:~# ./vpn_install

Será visualizado...
Cisco Systems VPN Client Version 4.8.02 (0030) Linux Installer
Copyright (C) 1998-2006 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]

Confirme o diretório...
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/2.6.27.7-smp/build]

* Binaries will be installed in "/usr/local/bin".
* Modules will be installed in "/lib/modules/2.6.27.7-smp/CiscoVPN".
* The VPN service will be started AUTOMATICALLY at boot time.
* Kernel source from "/lib/modules/2.6.27.7-smp/build" will be used to build the module.

Confirme o diretório...
Is the above correct [y]

Shutting down /opt/cisco-vpnclient/bin/vpnclient: module cisco_ipsec is not running.
Stopped: /etc/init.d/vpnclient_init (VPN init script)
Making module
make -C /lib/modules/2.6.27.7-smp/build SUBDIRS=/home/downloads/vpnclient modules
make[1]: Entering directory `/usr/src/linux-2.6.27.7'
CC [M] /home/downloads/vpnclient/linuxcniapi.o
CC [M] /home/downloads/vpnclient/frag.o
CC [M] /home/downloads/vpnclient/IPSecDrvOS_linux.o
CC [M] /home/downloads/vpnclient/interceptor.o
CC [M] /home/downloads/vpnclient/linuxkernelapi.o
LD [M] /home/downloads/vpnclient/cisco_ipsec.o
Building modules, stage 2.
MODPOST 1 modules
CC /home/downloads/vpnclient/cisco_ipsec.mod.o
LD [M] /home/downloads/vpnclient/cisco_ipsec.ko
make[1]: Leaving directory `/usr/src/linux-2.6.27.7'
Copying module to directory "/lib/modules/2.6.27.7-smp/CiscoVPN".
Already have group 'bin'

Creating start/stop script "/etc/init.d/vpnclient_init".
/etc/init.d/vpnclient_init
Enabling start/stop script for run level 3,4 and 5.

Installing license.txt (VPN Client license) in "/opt/cisco-vpnclient/":
/opt/cisco-vpnclient/license.txt

Installing bundled user profiles in "/etc/opt/cisco-vpnclient/Profiles/":
* New Profiles : sample

Copying binaries to directory "/opt/cisco-vpnclient/bin".
Adding symlinks to "/usr/local/bin".
/opt/cisco-vpnclient/bin/vpnclient
/opt/cisco-vpnclient/bin/cisco_cert_mgr
/opt/cisco-vpnclient/bin/ipseclog
Copying setuid binaries to directory "/opt/cisco-vpnclient/bin".
/opt/cisco-vpnclient/bin/cvpnd
Copying libraries to directory "/opt/cisco-vpnclient/lib".
/opt/cisco-vpnclient/lib/libvpnapi.so
Copying header files to directory "/opt/cisco-vpnclient/include".
/opt/cisco-vpnclient/include/vpnapi.h

Setting permissions.
/opt/cisco-vpnclient/bin/cvpnd (setuid root)
/opt/cisco-vpnclient (group bin readable)
/etc/opt/cisco-vpnclient (permissions not changed)
* You may wish to change these permissions to restrict access to root.
* You must run "/etc/init.d/vpnclient_init start" before using the client.
* This script will be run AUTOMATICALLY every time you reboot your computer.

5) Carregando o módulo...
root@spinho:~# /etc/init.d/vpnclient_init start

Será visualizado...
Starting /opt/cisco-vpnclient/bin/vpnclient: Done

A conexão só pode ser efetuada de posse do arquivo com as configurações de acesso para a rede desejada (“.pcf”).

6) Importando o arquivo “.pcf”. A seguir, exemplificamos com o arquivo “spinho.pcf”...
root@spinho:~# mv spinho.pcf /etc/opt/cisco-vpnclient/Profiles/

7) Conectando na rede pelo Cisco VPN Client. Mero exemplo, a seguir...
root@spinho:~# vpnclient connect spinho

No meu caso, de acordo com minha configuração...

User Authentication for spinho...

The server has requested the following information to complete the user authentication:

Username [spinho]:
Password []:
Authenticating user.
Negotiating security policies.
Securing communication channel.

Your VPN connection is secure.

Saudações Tecnológicas,
Jessé Spinho.