Setting up a CIPE VPN

Adam Haeder

Technical Coordinator,

Applied Information Management Institute

Omaha, NE

adamh@omaha.org

8/7/2001

For the Omaha Linux User's Group

What is a VPN?

Official definition: a private data network that makes use of the public telecommunication infrastructure, maintaining privacy through the use of a tunneling protocol and security procedures. A virtual private network can be contrasted with a system of owned or leased lines that can only be used by one company.

Basically, creating a private network over a public one

Examples of Tunneling Protocols

Free S/WAN

IPSEC implementation

PPTP

Point-to-Point Tunneling Protocol

Developed by Ascend ,Microsoft, 3Com, ECI Telematics, and U.S. Robotics.

Default VPN solution on Windows machines

VTUN - Virtual Tunnel

Runs on Linux, Solaris, *BSD

CIPE

Crypto IP Encapsulation

Many others, most at the application level

CIPE Overview

http://sites.inka.de/sites/bigred/devel/cipe.html

Tunneling IP packets in encrypted UDP packets

Consists of two parts:

Kernel module: cipcb

User-space program: ciped-cb

Uses blowfish encryption by default, does support other encryption algorithms

CIPE Overview (cont.)

Two machines running CIPE communicate with each other using two chosen UDP ports

Sets up one (or more) "virtual" interface(s)

cipcb1, cipcb2, etc.

These interfaces can be treated like any other interfaces:

Configured with ifconfig

Added to the existing routing table

Firewalled with ipchains

Test Environment

System Configs

Client 1 & Client 2

Any generic Windows box

Client 1 IP: 192.168.1.10/24	Gateway: 192.168.1.1 (CIPE 1)

Client 2 IP: 192.168.2.10/24	Gateway: 192.168.2.1 (CIPE 2)

CIPE 1

Pentium 200/32M/2.5G/2 RTL8139 NICS

RH7.0 (with updates), CIPE 1.4, ipchains

IP (Internal): 192.168.1.1/24

IP (External): 10.1.1.1/24

System Configs (cont.)

Sniffer

Sony Vaio laptop running RedHat 7.1 and Ethereal

IP: 10.1.1.10/24

CIPE 2

Pentium 90/24M/500MB/2 RTL8139 Nics

RH7.0 (with updates), CIPE 1.4, ipchains

IP (Internal): 192.168.2.1/24

IP (External): 10.1.1.2/24

2001-08-05T16:10:02