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Virtual Private NetworksVirtual Private Networks
Alberto Pace
IT/IS Technical Meeting – January 2002
What is a VPN ?What is a VPN ?
A technology that allows to send confidential data securely over the internet
IT/IS Technical Meeting – January 2002
What is a VPN ?What is a VPN ?
The remote computer can connect to the internet using an arbitrary Internet Service Provider (ISP) and have an IP Address in the intranet.
The computer can act as if it was on the intranet
IT/IS Technical Meeting – January 2002
Point-to-Point Tunneling ProtocolPoint-to-Point Tunneling Protocol
You can access a private network through the Internet or other public network by using a virtual private network (VPN) connection with the Point-to-Point Tunneling Protocol (PPTP).
Developed as an extension of the Point-to-Point Protocol (PPP),
PPTP tunnels or encapsulates, IP, IPX, or NetBEUI protocols inside of PPP datagrams
PPTP does not require a dial-up connection. It does, however, require IP connectivity between your computer and the server
My understanding is that it uses Microsoft Point-to-Point Encryption (MPPE)
IT/IS Technical Meeting – January 2002
Layer Two Tunneling ProtocolLayer Two Tunneling Protocol
L2TP is an industry-standard Internet tunneling protocol with roughly the same functionality as the Point-to-Point Tunneling Protocol (PPTP).
Like PPTP, L2TP encapsulates Point-to-Point Protocol (PPP) frames, which in turn encapsulate IP, IPX, or NetBEUI protocols
With L2TP, the computer performs all security checks and validations, and enables data encryption, which makes it much safer to send information over nonsecure networks by using the new Internet Protocol security (IPSec)
In this case data transfer through a L2TP-enabled VPN is as secure as within a single LAN at a corporate site
IT/IS Technical Meeting – January 2002
Internet Protocol security (IPSec) Internet Protocol security (IPSec)
IPSec provides machine-level authentication, as well as data encryption.
IPSec negotiates between your computer and its remote tunnel server before an L2TP connection is established, which secures both passwords and data
IT/IS Technical Meeting – January 2002
Authentication MethodsAuthentication Methods
Challenge Handshake Authentication Protocol (CHAP) Uses Message Digest 5 (MD5) / challenge-response
MS-CHAP Same as Chap + functionality to which LAN-based users are
accustomed MS-CHAP is consistent with standard CHAP (superset of
functionalities) You must at least use MS-CHAP to use MPPE (encryption)
MS-CHAP v2 both the client and the server prove their identities. Not only the client.
V2 ensures that you can configure a your connection can be configured to connect to the expected server
Extensible Authentication Protocol (EAP) Allows to use other security devices. EAP provides a standard
mechanism for support of additional authentication methods within PPP including token cards, one-time passwords, public key authentication using smart cards, certificates, and others
IT/IS Technical Meeting – January 2002
Types of VPNsTypes of VPNs
Router-to-Router
IT/IS Technical Meeting – January 2002
Types of VPNsTypes of VPNs
Remote Access VPNs
IT/IS Technical Meeting – January 2002
Tests at CERNTests at CERN
PCAP7 (computer in my office)
IT/IS Technical Meeting – January 2002
From the clientFrom the client
The machine we have in on the intranet only. We have to simulate internet/intranet.
The page http://cern.ch/Win/Temp/vpn.asp considers intranet the address 137.138.32.xxx
IT/IS Technical Meeting – January 2002
Connect to the VPNConnect to the VPN
From “My Network Places” – Right-Click – “Properties” – “Create New Connection”
IT/IS Technical Meeting – January 2002
Try to connectTry to connect
IT/IS Technical Meeting – January 2002
Conclusions so farConclusions so far
If we open the pptp port on address 137.138.33.62, we have today a working solution with the following limitations Uses PPTP and Microsoft Point-to-Point Encryption
Windows computer have all necessary software natively Windows Machines can be identified (as member of the
domain or an ad-hoc domain) Security is strengthened by domain logon that can be
tightened to anything you want This is the current “industry standard”
Used world-wide, secure and proven technology Evolution towards L2TP and IPSec coming, but slowly
(requires heavy infrastructure)
IT/IS Technical Meeting – January 2002
More conclusion so farMore conclusion so far
Using this technology, we could open rapidly a VPN service for WINDOWS users
Time to install and configure the VPN server ~ 8 hours Time to install a windows client that has already TCP/IP connectivity ~
1 minute Support for Linux users could come for the “community”
May be very expensive to formally support Linux clients Not a standard technology – to my knowledge, no companies have
“roaming linux users” on the internet to the same extent that we have Deploying the IPsec infrastructure to support L2TP will require an
administrative office to distribute, revoke and maintain computer certificates and user certificates.
May not be possible within the current resources / May require several years
Yet another computer Registration ? Yet another user Registration ? Should try to have LANDB and CCDB moving in this direction. Only if this
happens the investment can be justified.
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