Configuring VPN connections with Linux clients
Supporting IPsec via the 2.6 Kernel
Make sure you install the right supporting daemons for your connection. If your system uses any version of the 2.6 kernel, it natively supports IPsec, but if you want to use KVpnc or vpnc, you'll still need to install the racoon daemon, which takes care of the key exchange for IPsec implementations. To install racoon, use your native package manager or look online for instructions on building a racoon connection .
To support FreeS/WAN, the older IPsec standard, you'll have to install the ipsec daemon. If you fail to install the appropriate daemon, your VPN implementation will fail because it will be impossible for your system to conduct the necessary key exchanges when establishing the tunnel.
Establishing VPN today has gotten much easier, but the GUI VPN clients still don't do it all for you. Although working with Microsoft, Cisco, and OpenVPN servers requires a bit of troubleshooting acumen, if you keep working at it, you'll find success.
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