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Tuesday, April 29, 2008
فقط برای تو!
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VLAN
What is a VLAN? How to Setup a VLAN on a Cisco Switch
Have you ever wondered what a Virtual LAN (or VLAN) is or been unclear as to why you would want one? If so, I have been in your place at one time too. Since then, I have learned a lot about what a VLAN is and how it can help me. In this article, I will share that knowledge with you.
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Preparing for Cisco CCNP Exams? These are the videos you need to get certified...
Whether you are studying for the BCSI, BCMSN, ONT, ISCW or all four, Train Signal's Cisco CCNP Training Series is the best out there. The instructor uses a "hands-on" method for teaching complex technologies. Each video covers all the bases and gives you more than enough test prep to pass any of your CCNP exams!
Daniel Petri
Click Here to Watch the Cisco CCNP Training Videos!
document.context='YTowOnt9';
What is a LAN?
Okay, most of you already know what a LAN is but let’s give it a definition to make sure. We have to do this because, if you don’t know what a LAN is, you can’t understand what a VLAN is.
A LAN is a local area network and is defined as all devices in the same broadcast domain. If you remember, routers stop broadcasts, switches just forward them.
What is a VLAN?
As I said, a VLAN is a virtual LAN. In technical terms, a VLAN is a broadcast domain created by switches. Normally, it is a router creating that broadcast domain. With VLAN’s, a switch can create the broadcast domain.
This works by, you, the administrator, putting some switch ports in a VLAN other than 1, the default VLAN. All ports in a single VLAN are in a single broadcast domain.
Because switches can talk to each other, some ports on switch A can be in VLAN 10 and other ports on switch B can be in VLAN 10. Broadcasts between these devices will not be seen on any other port in any other VLAN, other than 10. However, these devices can all communicate because they are on the same VLAN. Without additional configuration, they would not be able to communicate with any other devices, not in their VLAN.
Are VLANs required?
It is important to point out that you don’t have to configure a VLAN until your network gets so large and has so much traffic that you need one. Many times, people are simply using VLAN’s because the network they are working on was already using them.
Another important fact is that, on a Cisco switch, VLAN’s are enabled by default and ALL devices are already in a VLAN. The VLAN that all devices are already in is VLAN 1. So, by default, you can just use all the ports on a switch and all devices will be able to talk to one another.
When do I need a VLAN?
You need to consider using VLAN’s in any of the following situations:
You have more than 200 devices on your LAN
You have a lot of broadcast traffic on your LAN
Groups of users need more security or are being slowed down by too many broadcasts?
Groups of users need to be on the same broadcast domain because they are running the same applications. An example would be a company that has VoIP phones. The users using the phone could be on a different VLAN, not with the regular users.
Or, just to make a single switch into multiple virtual switches.
Why not just subnet my network?
A common question is why not just subnet the network instead of using VLAN’s? Each VLAN should be in its own subnet. The benefit that a VLAN provides over a subnetted network is that devices in different physical locations, not going back to the same router, can be on the same network. The limitation of subnetting a network with a router is that all devices on that subnet must be connected to the same switch and that switch must be connected to a port on the router.
With a VLAN, one device can be connected to one switch, another device can be connected to another switch, and those devices can still be on the same VLAN (broadcast domain).
How can devices on different VLAN’s communicate?
Devices on different VLAN’s can communicate with a router or a Layer 3 switch. As each VLAN is its own subnet, a router or Layer 3 switch must be used to route between the subnets.
What is a trunk port?
When there is a link between two switches or a router and a switch that carries the traffic of more than one VLAN, that port is a trunk port.
A trunk port must run a special trunking protocol. The protocol used would be Cisco’s proprietary Inter-switch link (ISL) or the IEEE standard 802.1q.
How do I create a VLAN?
Configuring VLAN’s can vary even between different models of Cisco switches. Your goals, no matter what the commands are, is to:
Create the new VLAN’s
Put each port in the proper VLAN
Let’s say we wanted to create VLAN’s 5 and 10. We want to put ports 2 & 3 in VLAN 5 (Marketing) and ports 4 and 5 in VLAN 10 (Human Resources). On a Cisco 2950 switch, here is how you would do it:
At this point, only ports 2 and 3 should be able to communicate with each other and ports 4 & 5 should be able to communicate. That is because each of these is in its own VLAN. For the device on port 2 to communicate with the device on port 4, you would have to configure a trunk port to a router so that it can strip off the VLAN information, route the packet, and add back the VLAN information.
What do VLAN’s offer?
VLAN’s offer higher performance for medium and large LAN’s because they limit broadcasts. As the amount of traffic and the number of devices grow, so does the number of broadcast packets. By using VLAN’s you are containing broadcasts.
VLAN’s also provide security because you are essentially putting one group of devices, in one VLAN, on their own network.
Article Summary
Here is what we have learned:
A VLAN is a broadcast domain formed by switches
Administrators must create the VLAN’s then assign what port goes in what VLAN, manually.
VLAN’s provide better performance for medium and large LAN’s.
All devices, by default, are in VLAN 1.
A trunk port is a special port that runs ISL or 802.1q so that it can carry traffic from more than one VLAN.
For devices in different VLAN’s to communicate, you must use a router of Layer 3 switch.
Related articles
You might also want to read the following related articles:
How a Cisco Switch functions on an Ethernet network
How to Recover a Lost Password on a Cisco Switch
How to Use HyperTerminal with Cisco Switches
Basics of Cisco Switch Administration - Part 1
Basics of Cisco Switch Administration - Part 2
Setup VLAN Trunking Protocol (VTP) on Cisco Switches
About the writer
David Davis (CCIE #9369, CWNA, MCSE, CISSP, Linux+, CEH) has been in the IT industry for 15 years. Currently, he manages a group of systems/network administrators for a privately owned retail company and authors IT-related material in his spare time. He has written over fifty articles, eight practice tests and three video courses and has co-authored one book. His website is at www.happyrouter.com.
David Davis is also one of the Petri.co.il forum moderators.
Get All Our Articles Directly
Have you ever wondered what a Virtual LAN (or VLAN) is or been unclear as to why you would want one? If so, I have been in your place at one time too. Since then, I have learned a lot about what a VLAN is and how it can help me. In this article, I will share that knowledge with you.
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//]]>-->
Preparing for Cisco CCNP Exams? These are the videos you need to get certified...
Whether you are studying for the BCSI, BCMSN, ONT, ISCW or all four, Train Signal's Cisco CCNP Training Series is the best out there. The instructor uses a "hands-on" method for teaching complex technologies. Each video covers all the bases and gives you more than enough test prep to pass any of your CCNP exams!
Daniel Petri
Click Here to Watch the Cisco CCNP Training Videos!
document.context='YTowOnt9';
What is a LAN?
Okay, most of you already know what a LAN is but let’s give it a definition to make sure. We have to do this because, if you don’t know what a LAN is, you can’t understand what a VLAN is.
A LAN is a local area network and is defined as all devices in the same broadcast domain. If you remember, routers stop broadcasts, switches just forward them.
What is a VLAN?
As I said, a VLAN is a virtual LAN. In technical terms, a VLAN is a broadcast domain created by switches. Normally, it is a router creating that broadcast domain. With VLAN’s, a switch can create the broadcast domain.
This works by, you, the administrator, putting some switch ports in a VLAN other than 1, the default VLAN. All ports in a single VLAN are in a single broadcast domain.
Because switches can talk to each other, some ports on switch A can be in VLAN 10 and other ports on switch B can be in VLAN 10. Broadcasts between these devices will not be seen on any other port in any other VLAN, other than 10. However, these devices can all communicate because they are on the same VLAN. Without additional configuration, they would not be able to communicate with any other devices, not in their VLAN.
Are VLANs required?
It is important to point out that you don’t have to configure a VLAN until your network gets so large and has so much traffic that you need one. Many times, people are simply using VLAN’s because the network they are working on was already using them.
Another important fact is that, on a Cisco switch, VLAN’s are enabled by default and ALL devices are already in a VLAN. The VLAN that all devices are already in is VLAN 1. So, by default, you can just use all the ports on a switch and all devices will be able to talk to one another.
When do I need a VLAN?
You need to consider using VLAN’s in any of the following situations:
You have more than 200 devices on your LAN
You have a lot of broadcast traffic on your LAN
Groups of users need more security or are being slowed down by too many broadcasts?
Groups of users need to be on the same broadcast domain because they are running the same applications. An example would be a company that has VoIP phones. The users using the phone could be on a different VLAN, not with the regular users.
Or, just to make a single switch into multiple virtual switches.
Why not just subnet my network?
A common question is why not just subnet the network instead of using VLAN’s? Each VLAN should be in its own subnet. The benefit that a VLAN provides over a subnetted network is that devices in different physical locations, not going back to the same router, can be on the same network. The limitation of subnetting a network with a router is that all devices on that subnet must be connected to the same switch and that switch must be connected to a port on the router.
With a VLAN, one device can be connected to one switch, another device can be connected to another switch, and those devices can still be on the same VLAN (broadcast domain).
How can devices on different VLAN’s communicate?
Devices on different VLAN’s can communicate with a router or a Layer 3 switch. As each VLAN is its own subnet, a router or Layer 3 switch must be used to route between the subnets.
What is a trunk port?
When there is a link between two switches or a router and a switch that carries the traffic of more than one VLAN, that port is a trunk port.
A trunk port must run a special trunking protocol. The protocol used would be Cisco’s proprietary Inter-switch link (ISL) or the IEEE standard 802.1q.
How do I create a VLAN?
Configuring VLAN’s can vary even between different models of Cisco switches. Your goals, no matter what the commands are, is to:
Create the new VLAN’s
Put each port in the proper VLAN
Let’s say we wanted to create VLAN’s 5 and 10. We want to put ports 2 & 3 in VLAN 5 (Marketing) and ports 4 and 5 in VLAN 10 (Human Resources). On a Cisco 2950 switch, here is how you would do it:
At this point, only ports 2 and 3 should be able to communicate with each other and ports 4 & 5 should be able to communicate. That is because each of these is in its own VLAN. For the device on port 2 to communicate with the device on port 4, you would have to configure a trunk port to a router so that it can strip off the VLAN information, route the packet, and add back the VLAN information.
What do VLAN’s offer?
VLAN’s offer higher performance for medium and large LAN’s because they limit broadcasts. As the amount of traffic and the number of devices grow, so does the number of broadcast packets. By using VLAN’s you are containing broadcasts.
VLAN’s also provide security because you are essentially putting one group of devices, in one VLAN, on their own network.
Article Summary
Here is what we have learned:
A VLAN is a broadcast domain formed by switches
Administrators must create the VLAN’s then assign what port goes in what VLAN, manually.
VLAN’s provide better performance for medium and large LAN’s.
All devices, by default, are in VLAN 1.
A trunk port is a special port that runs ISL or 802.1q so that it can carry traffic from more than one VLAN.
For devices in different VLAN’s to communicate, you must use a router of Layer 3 switch.
Related articles
You might also want to read the following related articles:
How a Cisco Switch functions on an Ethernet network
How to Recover a Lost Password on a Cisco Switch
How to Use HyperTerminal with Cisco Switches
Basics of Cisco Switch Administration - Part 1
Basics of Cisco Switch Administration - Part 2
Setup VLAN Trunking Protocol (VTP) on Cisco Switches
About the writer
David Davis (CCIE #9369, CWNA, MCSE, CISSP, Linux+, CEH) has been in the IT industry for 15 years. Currently, he manages a group of systems/network administrators for a privately owned retail company and authors IT-related material in his spare time. He has written over fifty articles, eight practice tests and three video courses and has co-authored one book. His website is at www.happyrouter.com.
David Davis is also one of the Petri.co.il forum moderators.
Get All Our Articles Directly
Monday, April 28, 2008
Virtual private network
"VPN" redirects here. For other uses, see VPN (disambiguation).
A virtual private network (VPN) is a communications network tunneled through another network, and dedicated for a specific network. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.
A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point. The distinguishing characteristic of VPNs are not security or performance, but that they overlay other network(s) to provide a certain functionality that is meaningful to a user community.
Contents[hide]
1 Business Case for Using VPN
2 Categorization by User Administrative Relationships
3 Routing
3.1 Building Blocks
3.1.1 Customer Edge Device (CE)
3.1.2 Provider Edge Device (PE)
3.1.3 Provider Device (P)
4 User-Visible PPVPN Services
4.1 Layer 1 Services
4.1.1 Virtual Private Wire and Private Line Services (VPWS and VPLS)
4.2 Layer 2 Services
4.2.1 Virtual LAN
4.2.2 Virtual Private LAN Service (VPLS)
4.2.3 Pseudo Wire (PW)
4.2.4 IP-Only LAN-Like Service (IPLS)
4.3 L3 PPVPN Architectures
4.3.1 BGP/MPLS PPVPN
4.3.2 Virtual Router PPVPN
5 Categorizing VPN Security Models
5.1 Authentication before VPN Connection
5.2 Trusted Delivery Networks
5.3 Security mechanisms in the VPN
5.4 Security and Mobility
5.5 See also
6 External links
7 References
//
[edit] Business Case for Using VPN
Attractions of VPNs to enterprises include:
Shared facilities may be cheaper—especially in capital expenditure (CAPEX)—than traditional routed networks over dedicated facilities.
Can rapidly link enterprise offices, as well as small-and-home-office and mobile workers.
Allow customization of security and quality of service as needed for specific applications.
Can scale to meet sudden demands, especially when provider-provisioned on shared infrastructure.
Can reduce operational expenditure (OPEX) by outsourcing support and facilities.
Distributing VPNs to homes, telecommuters, and small offices may put access to sensitive information in facilities not as well protected as more traditional facilities. VPNs need to be designed and operated under well-thought-out security policies. Organizations using them must have clear security rules supported by top management. When access goes beyond traditional office facilities, where there may be no professional administrators, security must be maintained as transparently as possible to end users.
Some organizations with especially sensitive data, such as health care companies, even arrange for an employee's home to have two separate WAN connections: one for working on that employer's sensitive data and one for all other uses.[citation needed] More common is that bringing up the secure VPN cuts off Internet connectivity for any use except secure communications into the enterprise; Internet access is still possible but will go through enterprise access rather than that of the local user.
In situations in which a company or individual has legal obligations to keep information confidential, there may be legal problems, even criminal ones, as a result. Two examples are the HIPAA regulations in the U.S. with regard to health data, and the more general European Union data privacy regulations which apply to even marketing and billing information and extend to those who share that data elsewhere.
[edit] Categorization by User Administrative Relationships
The Internet Engineering Task Force (IETF) categorized a variety of VPNs, some of which, such as Virtual LANs (VLAN) are the standardization responsibility of other organizations, such as the Institute of Electrical and Electronics Engineers (IEEE) Project 802, Workgroup 802.1 (architecture). Originally, network nodes within a single enterprise were interconnected with Wide Area Network (WAN) links from a telecommunications service provider. With the advent of LANs, enterprises could interconnect their nodes with links that they owned. While the original WANs used dedicated lines and layer 2 multiplexed services such as Frame Relay, IP-based layer 3 networks, such as the ARPANET, Internet, military IP networks (NIPRNET,SIPRNET,JWICS, etc.), became common interconnection media. VPNs began to be defined over IP networks [1]. The military networks may themselves be implemented as VPNs on common transmission equipment, but with separate encryption and perhaps routers.
It became useful first to distinguish among different kinds of IP VPN based on the administrative relationships, not the technology, interconnecting the nodes. Once the relationships were defined, different technologies could be used, depending on requirements such as security and quality of service.
When an enterprise interconnected a set of nodes, all under its administrative control, through an LAN network, that was termed an Intranet [2]. When the interconnected nodes were under multiple administrative authorities, but were hidden from the public Internet, the resulting set of nodes was called an extranet. Both intranets and extranets could be managed by a user organization, or the service could be obtained as a contracted offering, usually customized, from an IP service provider. In the latter case, the user organization contracted for layer 3 services much as it had contracted for layer 1 services such as dedicated lines, or multiplexed layer 2 services such as frame relay.
The IETF distinguishes between provider-provisioned and customer-provisioned VPNs [3]. Much as conventional WAN services can be provided by an interconnected set of providers, provider-provisioned VPNs (PPVPNs) can be provided by a single service provider that presents a common point of contact to the user organization.
[edit] Routing
Tunneling protocols can be used in a point-to-point topology that would generally not be considered a VPN, because a VPN is expected to support arbitrary and changing sets of network nodes. Since most router implementations support software-defined tunnel interface, customer-provisioned VPNs are often simply a set of tunnels over which conventional routing protocols run. PPVPNs, however, need to support the coexistence of multiple VPNs, hidden from one another, but operated by the same service provider.
[edit] Building Blocks
Depending on whether the PPVPN is layer 2 or layer 3, the building blocks described below may be L2 only, L3 only, or combinations of the two. MPLS functionality blurs the L2-L3 identity.
While these terms were generalized to cover L2 and L3 VPNs in RFC 4026, they were introduced in [4].
[edit] Customer Edge Device (CE)
In general, a CE is a device, physically at the customer premises, that provides access to the PPVPN service. Some implementations treat it purely as a demarcation point between provider and customer responsibility, while others allow it to be a customer-configurable device.
[edit] Provider Edge Device (PE)
A PE is a device or set of devices, at the edge of the provider network, which provides the provider's view of the customer site. PEs are aware of the VPNs that connect through them, and do maintain VPN state.
[edit] Provider Device (P)
A P device is inside the provider's core network, and does not directly interface to any customer endpoint. It might, for example, be used to provide routing for many provider-operated tunnels that belong to different customers' PPVPNs. While the P device is a key part of implementing PPVPNs, it is not itself VPN-aware and does not maintain VPN state. Its principal role is allowing the service provider to scale its PPVPN offerings, as, for example, by acting as an aggregation point for multiple PEs. P-to-P connections, in such a role, often are high-capacity optical links between major locations of provider.
[edit] User-Visible PPVPN Services
This section deals with the types of VPN currently considered active in the IETF; some historical names were replaced by these terms.
[edit] Layer 1 Services
[edit] Virtual Private Wire and Private Line Services (VPWS and VPLS)
In both of these services, the provider does not offer a full routed or bridged network, but components from which the customer can build customer-administered networks. VPWS are point-to-point while VPLS can be point-to-multipoint. They can be Layer 1 emulated circuits with no data link structure.
It is the customer that determines the overall customer VPN service, which can involve routing, bridging, or host network elements.
There is an unfortunate acronym collision between Virtual Private Line Service and Virtual Private LAN Service; the context should make it clear whether the layer 1 virtual private line or the layer 2 virtual private LAN is meant.
[edit] Layer 2 Services
[edit] Virtual LAN
A Layer 2 technique that allows for the coexistence of multiple LAN broadcast domains, interconnected via trunks using the IEEE 802.1Q trunking protocol. Other trunking protocols have been used but are obsolete, including Inter-Switch Link (ISL), IEEE 802.10 (originally a security protocol but a subset was introduced for trunking), and ATM LAN Emulation (LANE).
[edit] Virtual Private LAN Service (VPLS)
Developed by IEEE, VLANs allow multiple tagged LANs to share common trunking. VLANs frequently are composed only of customer-owned facilities. The former is a layer 1 technology that supports emulation of both point-to-point and point-to-multipoint topologies. The method discussed here is an extension of Layer 2 technologies such as 802.1d and 802.1q LAN trunking, extended to run over transports such as Metro Ethernet.
As used in this context rather than private line, a VPLS is a Layer 2 PPVPN that emulates the full functionality of a traditional Local Area Network (LAN). From the user standpoint, VPLS makes it possible to interconnect several LAN segments over a packet-switched or optical provider core, a core transparent to the customer, and makes the remote LAN segments behave as one single LAN.
In a VPLS, the provider network emulates a learning bridge, which optionally may include VLAN service.
[edit] Pseudo Wire (PW)
PW is similar to VPWS, but it can provide different L2 protocols at both ends. Typically, its interface is a WAN protocol such as ATM or Frame Relay. In contrast, when the goal is to provide the appearance of a LAN contiguous between two or more locations, the Virtual Private LAN service or IPLS would be appropriate.
[edit] IP-Only LAN-Like Service (IPLS)
A subset of VPLS, the CE devices must have L3 capabilities; the IPLS presents packets rather than frames. It may support IPv4 or IPv6.
[edit] L3 PPVPN Architectures
This section discusses the main architectures for PPVPNs, one where the PE disambiguates duplicate addresses in a single routing instance, and the other, virtual router, in which the PE contains a virtual router instance per VPN. The former approach, and its variants, have gained the most attention.
One of the challenges of PPVPNs is that different customers may use the same address space, especially the IPv4 private address space[5]. The provider must be able to disambiguate overlapping addresses in the multiple customers' PPVPNs.
[edit] BGP/MPLS PPVPN
In the method defined by RFC 2547, BGP extensions are used to advertise routes in the IPv4 VPN address family, which are of the form of 12-byte strings, beginning with an 8-byte Route Distinguisher (RD) and ending with a 4-byte IPv4 address. RDs disambiguate otherwise duplicate addresses in the same PE.
PEs understand the topology of each VPN, which are interconnected with MPLS tunnels, either directly or via P routers. In MPLS terminology, the P routers are Label Switch Routers without awareness of VPNs.
[edit] Virtual Router PPVPN
The Virtual Router architecture [6], as opposed to BGP/MPLS techniques, requires no modification to existing routing protocols such as BGP. By the provisioning of logically independent routing domains, the customer operating a VPN is completely responsible for the address space. In the various MPLS tunnels, the different PPVPNs are disambiguated by their label, but do not need routing distinguishers.
Virtual router architectures do not need to disambiguate addresses, because rather than a PE router having awareness of all the PPVPNs, the PE contains multiple virtual router instances, which belong to one and only one VPN.
[edit] Categorizing VPN Security Models
From the security standpoint, either the underlying delivery network is trusted, or the VPN must enforce security with mechanisms in the VPN itself. Unless the trusted delivery network runs only among physically secure sites, both trusted and secure models need an authentication mechanism for users to gain access to the VPN.
Some ISPs now offer managed VPN service for business customers who want the security and convenience of a VPN but prefer not to undertake administering a VPN server themselves. Managed VPNs go beyond PPVPN scope, and are a contracted security solution that can reach into hosts. In addition to providing remote workers with secure access to their employer's internal network, other security and management services are sometimes included as part of the package. Examples include keeping anti-virus and anti-spyware programs updated on each client's computer.
[edit] Authentication before VPN Connection
A known trusted user, sometimes only when using trusted devices, can be provided with appropriate security privileges to access resources not available to general users. Servers may also need to authenticate themselves to join the VPN.
There are a wide variety of authentication mechanisms, which may be implemented in devices including firewalls, access gateways, and other devices. They may use passwords, biometrics, or cryptographic methods. Strong authentication involves combining cryptography with another authentication mechanism. The authentication mechanism may require explicit user action, or may be embedded in the VPN client or the workstation.
[edit] Trusted Delivery Networks
Trusted VPNs (sometimes referred to APNs - Actual Private Networks)[citation needed] do not use cryptographic tunneling, and instead rely on the security of a single provider's network to protect the traffic. In a sense, these are an elaboration of traditional network and system administration work.
Multi-Protocol Label Switching (MPLS) is often used to overlay VPNs, often with quality of service control over a trusted delivery network.
Layer 2 Tunneling Protocol (L2TP)[7] which is a standards-based replacement, and a compromise taking the good features from each, for two proprietary VPN protocols: Cisco's Layer 2 Forwarding (L2F) [8] (now obsolete) and Microsoft's Point-to-Point Tunneling Protocol (PPTP) [9].
[edit] Security mechanisms in the VPN
Secure VPNs use cryptographic tunneling protocols to provide the intended confidentiality (blocking snooping and thus Packet sniffing), sender authentication (blocking identity spoofing), and message integrity (blocking message alteration) to achieve privacy. When properly chosen, implemented, and used, such techniques can provide secure communications over unsecured networks.
Secure VPN protocols include the following:
IPsec (IP security) - commonly used over IPv4, and an obligatory part of IPv6.
SSL/TLS used either for tunneling the entire network stack, as in the OpenVPN project, or for securing what is, essentially, a web proxy. SSL is a framework more often associated with e-commerce, but it has been built-upon by a number of vendors to provide remote access VPN capabilities. A major practical advantage of an SSL-based VPN is that it can be accessed from the locations that restrict external access to SSL-based e-commerce websites only, thereby preventing VPN connectivity using IPsec protocols. SSL-based VPNs are vulnerable to trivial Denial of Service attacks mounted against their TCP connections because latter are inherently unauthenticated.
OpenVPN, an open standard VPN. It is a variation of SSL-based VPN that is capable of running over UDP. Clients and servers are available for all major operating systems.
L2TPv3 (Layer 2 Tunneling Protocol version 3), a new release.
VPN Quarantine The client machine at the end of a VPN could be a threat and a source of attack; this has no connection with VPN design and is usually left to system administration efforts. There are solutions that provide VPN Quarantine services which run end point checks on the remote client while the client is kept in a quarantine zone until healthy. Microsoft ISA Server 2004/2006 together with VPN-Q 2006 from Winfrasoft or an application called QSS (Quarantine Security Suite) provide this functionality.
MPVPN (Multi Path Virtual Private Network). MPVPN is a registered trademark owned by Ragula Systems Development Company. See Trademark Applications and Registrations Retrieval (TARR)
[edit] Security and Mobility
Mobile VPNs are VPNs designed for mobile and wireless users. They integrate standards-based authentication and encryption technologies to secure data transmissions to and from devices and to protect networks from unauthorized users. Designed for wireless environments, Mobile VPNs are designed as an access solution for users that are on the move and require secure access to information and applications over a variety of wired and wireless networks. Mobile VPNs allow users to roam seamlessly across IP-based networks and in and out of wireless coverage areas without losing application sessions or dropping the secure VPN session. For instance, highway patrol officers require access to mission-critical applications in order to perform their jobs as they travel across different subnets of a mobile network, much as a cellular radio has to hand off its link to repeaters at different cell towers.
[edit] See also
IPsec
SSL
Opportunistic encryption
Split tunneling
Intranet
Local Area Network
[edit] External links
JANET UK 'Different Flavours of VPN: Technology and Applications'
VPN Encryption
Virtual Private Network Consortium - trade association for VPN vendors
Microsoft TechNet VPN Resources
ZeroShell a small Linux distribution which is able to act as VPN box for LAN-to-LAN and host-to-LAN VPNs
Tutorial Using the Built-in Windows PPTP VPN Function
How Virtual Private Networks Work - A basic tutorial
OpenVPN Free cross platform VPN server/client
[edit] References
^ IP Based Virtual Private Networks,RFC 2764, B. Gleeson et al.,February2000
^ Generic Requirements for Provider Provisioned Virtual Private Networks (PPVPN),RFC3809, A. Nagarajan,June 2004
^ Provider Provisioned Virtual Private Network (VPN) Terminology,RFC4026, L. Andersson and T. Madsen,March 2005
^ BGP/MPLS VPNs,RFC 2547, E. Rosen & Y. Rekhter,March 1999
^ Address Allocation for Private Internets,RFC 1918, Y. Rekhter et al.,February 1996
^ A Core MPLS IP VPN Architecture,RFC 2918, K. Muthukrishnan& A. Malis,September 2000
^ Layer Two Tunneling Protocol "L2TP",RFC 2661, W. Townsley et al.,August 1999
^ IP Based Virtual Private Networks,RFC 2341, A. Valencia et al.,May 1998
^ Point-to-Point Tunneling Protocol (PPTP),RFC 2637, K. Hamzeh et al.,July 1999
A virtual private network (VPN) is a communications network tunneled through another network, and dedicated for a specific network. One common application is secure communications through the public Internet, but a VPN need not have explicit security features, such as authentication or content encryption. VPNs, for example, can be used to separate the traffic of different user communities over an underlying network with strong security features.
A VPN may have best-effort performance, or may have a defined service level agreement (SLA) between the VPN customer and the VPN service provider. Generally, a VPN has a topology more complex than point-to-point. The distinguishing characteristic of VPNs are not security or performance, but that they overlay other network(s) to provide a certain functionality that is meaningful to a user community.
Contents[hide]
1 Business Case for Using VPN
2 Categorization by User Administrative Relationships
3 Routing
3.1 Building Blocks
3.1.1 Customer Edge Device (CE)
3.1.2 Provider Edge Device (PE)
3.1.3 Provider Device (P)
4 User-Visible PPVPN Services
4.1 Layer 1 Services
4.1.1 Virtual Private Wire and Private Line Services (VPWS and VPLS)
4.2 Layer 2 Services
4.2.1 Virtual LAN
4.2.2 Virtual Private LAN Service (VPLS)
4.2.3 Pseudo Wire (PW)
4.2.4 IP-Only LAN-Like Service (IPLS)
4.3 L3 PPVPN Architectures
4.3.1 BGP/MPLS PPVPN
4.3.2 Virtual Router PPVPN
5 Categorizing VPN Security Models
5.1 Authentication before VPN Connection
5.2 Trusted Delivery Networks
5.3 Security mechanisms in the VPN
5.4 Security and Mobility
5.5 See also
6 External links
7 References
//
[edit] Business Case for Using VPN
Attractions of VPNs to enterprises include:
Shared facilities may be cheaper—especially in capital expenditure (CAPEX)—than traditional routed networks over dedicated facilities.
Can rapidly link enterprise offices, as well as small-and-home-office and mobile workers.
Allow customization of security and quality of service as needed for specific applications.
Can scale to meet sudden demands, especially when provider-provisioned on shared infrastructure.
Can reduce operational expenditure (OPEX) by outsourcing support and facilities.
Distributing VPNs to homes, telecommuters, and small offices may put access to sensitive information in facilities not as well protected as more traditional facilities. VPNs need to be designed and operated under well-thought-out security policies. Organizations using them must have clear security rules supported by top management. When access goes beyond traditional office facilities, where there may be no professional administrators, security must be maintained as transparently as possible to end users.
Some organizations with especially sensitive data, such as health care companies, even arrange for an employee's home to have two separate WAN connections: one for working on that employer's sensitive data and one for all other uses.[citation needed] More common is that bringing up the secure VPN cuts off Internet connectivity for any use except secure communications into the enterprise; Internet access is still possible but will go through enterprise access rather than that of the local user.
In situations in which a company or individual has legal obligations to keep information confidential, there may be legal problems, even criminal ones, as a result. Two examples are the HIPAA regulations in the U.S. with regard to health data, and the more general European Union data privacy regulations which apply to even marketing and billing information and extend to those who share that data elsewhere.
[edit] Categorization by User Administrative Relationships
The Internet Engineering Task Force (IETF) categorized a variety of VPNs, some of which, such as Virtual LANs (VLAN) are the standardization responsibility of other organizations, such as the Institute of Electrical and Electronics Engineers (IEEE) Project 802, Workgroup 802.1 (architecture). Originally, network nodes within a single enterprise were interconnected with Wide Area Network (WAN) links from a telecommunications service provider. With the advent of LANs, enterprises could interconnect their nodes with links that they owned. While the original WANs used dedicated lines and layer 2 multiplexed services such as Frame Relay, IP-based layer 3 networks, such as the ARPANET, Internet, military IP networks (NIPRNET,SIPRNET,JWICS, etc.), became common interconnection media. VPNs began to be defined over IP networks [1]. The military networks may themselves be implemented as VPNs on common transmission equipment, but with separate encryption and perhaps routers.
It became useful first to distinguish among different kinds of IP VPN based on the administrative relationships, not the technology, interconnecting the nodes. Once the relationships were defined, different technologies could be used, depending on requirements such as security and quality of service.
When an enterprise interconnected a set of nodes, all under its administrative control, through an LAN network, that was termed an Intranet [2]. When the interconnected nodes were under multiple administrative authorities, but were hidden from the public Internet, the resulting set of nodes was called an extranet. Both intranets and extranets could be managed by a user organization, or the service could be obtained as a contracted offering, usually customized, from an IP service provider. In the latter case, the user organization contracted for layer 3 services much as it had contracted for layer 1 services such as dedicated lines, or multiplexed layer 2 services such as frame relay.
The IETF distinguishes between provider-provisioned and customer-provisioned VPNs [3]. Much as conventional WAN services can be provided by an interconnected set of providers, provider-provisioned VPNs (PPVPNs) can be provided by a single service provider that presents a common point of contact to the user organization.
[edit] Routing
Tunneling protocols can be used in a point-to-point topology that would generally not be considered a VPN, because a VPN is expected to support arbitrary and changing sets of network nodes. Since most router implementations support software-defined tunnel interface, customer-provisioned VPNs are often simply a set of tunnels over which conventional routing protocols run. PPVPNs, however, need to support the coexistence of multiple VPNs, hidden from one another, but operated by the same service provider.
[edit] Building Blocks
Depending on whether the PPVPN is layer 2 or layer 3, the building blocks described below may be L2 only, L3 only, or combinations of the two. MPLS functionality blurs the L2-L3 identity.
While these terms were generalized to cover L2 and L3 VPNs in RFC 4026, they were introduced in [4].
[edit] Customer Edge Device (CE)
In general, a CE is a device, physically at the customer premises, that provides access to the PPVPN service. Some implementations treat it purely as a demarcation point between provider and customer responsibility, while others allow it to be a customer-configurable device.
[edit] Provider Edge Device (PE)
A PE is a device or set of devices, at the edge of the provider network, which provides the provider's view of the customer site. PEs are aware of the VPNs that connect through them, and do maintain VPN state.
[edit] Provider Device (P)
A P device is inside the provider's core network, and does not directly interface to any customer endpoint. It might, for example, be used to provide routing for many provider-operated tunnels that belong to different customers' PPVPNs. While the P device is a key part of implementing PPVPNs, it is not itself VPN-aware and does not maintain VPN state. Its principal role is allowing the service provider to scale its PPVPN offerings, as, for example, by acting as an aggregation point for multiple PEs. P-to-P connections, in such a role, often are high-capacity optical links between major locations of provider.
[edit] User-Visible PPVPN Services
This section deals with the types of VPN currently considered active in the IETF; some historical names were replaced by these terms.
[edit] Layer 1 Services
[edit] Virtual Private Wire and Private Line Services (VPWS and VPLS)
In both of these services, the provider does not offer a full routed or bridged network, but components from which the customer can build customer-administered networks. VPWS are point-to-point while VPLS can be point-to-multipoint. They can be Layer 1 emulated circuits with no data link structure.
It is the customer that determines the overall customer VPN service, which can involve routing, bridging, or host network elements.
There is an unfortunate acronym collision between Virtual Private Line Service and Virtual Private LAN Service; the context should make it clear whether the layer 1 virtual private line or the layer 2 virtual private LAN is meant.
[edit] Layer 2 Services
[edit] Virtual LAN
A Layer 2 technique that allows for the coexistence of multiple LAN broadcast domains, interconnected via trunks using the IEEE 802.1Q trunking protocol. Other trunking protocols have been used but are obsolete, including Inter-Switch Link (ISL), IEEE 802.10 (originally a security protocol but a subset was introduced for trunking), and ATM LAN Emulation (LANE).
[edit] Virtual Private LAN Service (VPLS)
Developed by IEEE, VLANs allow multiple tagged LANs to share common trunking. VLANs frequently are composed only of customer-owned facilities. The former is a layer 1 technology that supports emulation of both point-to-point and point-to-multipoint topologies. The method discussed here is an extension of Layer 2 technologies such as 802.1d and 802.1q LAN trunking, extended to run over transports such as Metro Ethernet.
As used in this context rather than private line, a VPLS is a Layer 2 PPVPN that emulates the full functionality of a traditional Local Area Network (LAN). From the user standpoint, VPLS makes it possible to interconnect several LAN segments over a packet-switched or optical provider core, a core transparent to the customer, and makes the remote LAN segments behave as one single LAN.
In a VPLS, the provider network emulates a learning bridge, which optionally may include VLAN service.
[edit] Pseudo Wire (PW)
PW is similar to VPWS, but it can provide different L2 protocols at both ends. Typically, its interface is a WAN protocol such as ATM or Frame Relay. In contrast, when the goal is to provide the appearance of a LAN contiguous between two or more locations, the Virtual Private LAN service or IPLS would be appropriate.
[edit] IP-Only LAN-Like Service (IPLS)
A subset of VPLS, the CE devices must have L3 capabilities; the IPLS presents packets rather than frames. It may support IPv4 or IPv6.
[edit] L3 PPVPN Architectures
This section discusses the main architectures for PPVPNs, one where the PE disambiguates duplicate addresses in a single routing instance, and the other, virtual router, in which the PE contains a virtual router instance per VPN. The former approach, and its variants, have gained the most attention.
One of the challenges of PPVPNs is that different customers may use the same address space, especially the IPv4 private address space[5]. The provider must be able to disambiguate overlapping addresses in the multiple customers' PPVPNs.
[edit] BGP/MPLS PPVPN
In the method defined by RFC 2547, BGP extensions are used to advertise routes in the IPv4 VPN address family, which are of the form of 12-byte strings, beginning with an 8-byte Route Distinguisher (RD) and ending with a 4-byte IPv4 address. RDs disambiguate otherwise duplicate addresses in the same PE.
PEs understand the topology of each VPN, which are interconnected with MPLS tunnels, either directly or via P routers. In MPLS terminology, the P routers are Label Switch Routers without awareness of VPNs.
[edit] Virtual Router PPVPN
The Virtual Router architecture [6], as opposed to BGP/MPLS techniques, requires no modification to existing routing protocols such as BGP. By the provisioning of logically independent routing domains, the customer operating a VPN is completely responsible for the address space. In the various MPLS tunnels, the different PPVPNs are disambiguated by their label, but do not need routing distinguishers.
Virtual router architectures do not need to disambiguate addresses, because rather than a PE router having awareness of all the PPVPNs, the PE contains multiple virtual router instances, which belong to one and only one VPN.
[edit] Categorizing VPN Security Models
From the security standpoint, either the underlying delivery network is trusted, or the VPN must enforce security with mechanisms in the VPN itself. Unless the trusted delivery network runs only among physically secure sites, both trusted and secure models need an authentication mechanism for users to gain access to the VPN.
Some ISPs now offer managed VPN service for business customers who want the security and convenience of a VPN but prefer not to undertake administering a VPN server themselves. Managed VPNs go beyond PPVPN scope, and are a contracted security solution that can reach into hosts. In addition to providing remote workers with secure access to their employer's internal network, other security and management services are sometimes included as part of the package. Examples include keeping anti-virus and anti-spyware programs updated on each client's computer.
[edit] Authentication before VPN Connection
A known trusted user, sometimes only when using trusted devices, can be provided with appropriate security privileges to access resources not available to general users. Servers may also need to authenticate themselves to join the VPN.
There are a wide variety of authentication mechanisms, which may be implemented in devices including firewalls, access gateways, and other devices. They may use passwords, biometrics, or cryptographic methods. Strong authentication involves combining cryptography with another authentication mechanism. The authentication mechanism may require explicit user action, or may be embedded in the VPN client or the workstation.
[edit] Trusted Delivery Networks
Trusted VPNs (sometimes referred to APNs - Actual Private Networks)[citation needed] do not use cryptographic tunneling, and instead rely on the security of a single provider's network to protect the traffic. In a sense, these are an elaboration of traditional network and system administration work.
Multi-Protocol Label Switching (MPLS) is often used to overlay VPNs, often with quality of service control over a trusted delivery network.
Layer 2 Tunneling Protocol (L2TP)[7] which is a standards-based replacement, and a compromise taking the good features from each, for two proprietary VPN protocols: Cisco's Layer 2 Forwarding (L2F) [8] (now obsolete) and Microsoft's Point-to-Point Tunneling Protocol (PPTP) [9].
[edit] Security mechanisms in the VPN
Secure VPNs use cryptographic tunneling protocols to provide the intended confidentiality (blocking snooping and thus Packet sniffing), sender authentication (blocking identity spoofing), and message integrity (blocking message alteration) to achieve privacy. When properly chosen, implemented, and used, such techniques can provide secure communications over unsecured networks.
Secure VPN protocols include the following:
IPsec (IP security) - commonly used over IPv4, and an obligatory part of IPv6.
SSL/TLS used either for tunneling the entire network stack, as in the OpenVPN project, or for securing what is, essentially, a web proxy. SSL is a framework more often associated with e-commerce, but it has been built-upon by a number of vendors to provide remote access VPN capabilities. A major practical advantage of an SSL-based VPN is that it can be accessed from the locations that restrict external access to SSL-based e-commerce websites only, thereby preventing VPN connectivity using IPsec protocols. SSL-based VPNs are vulnerable to trivial Denial of Service attacks mounted against their TCP connections because latter are inherently unauthenticated.
OpenVPN, an open standard VPN. It is a variation of SSL-based VPN that is capable of running over UDP. Clients and servers are available for all major operating systems.
L2TPv3 (Layer 2 Tunneling Protocol version 3), a new release.
VPN Quarantine The client machine at the end of a VPN could be a threat and a source of attack; this has no connection with VPN design and is usually left to system administration efforts. There are solutions that provide VPN Quarantine services which run end point checks on the remote client while the client is kept in a quarantine zone until healthy. Microsoft ISA Server 2004/2006 together with VPN-Q 2006 from Winfrasoft or an application called QSS (Quarantine Security Suite) provide this functionality.
MPVPN (Multi Path Virtual Private Network). MPVPN is a registered trademark owned by Ragula Systems Development Company. See Trademark Applications and Registrations Retrieval (TARR)
[edit] Security and Mobility
Mobile VPNs are VPNs designed for mobile and wireless users. They integrate standards-based authentication and encryption technologies to secure data transmissions to and from devices and to protect networks from unauthorized users. Designed for wireless environments, Mobile VPNs are designed as an access solution for users that are on the move and require secure access to information and applications over a variety of wired and wireless networks. Mobile VPNs allow users to roam seamlessly across IP-based networks and in and out of wireless coverage areas without losing application sessions or dropping the secure VPN session. For instance, highway patrol officers require access to mission-critical applications in order to perform their jobs as they travel across different subnets of a mobile network, much as a cellular radio has to hand off its link to repeaters at different cell towers.
[edit] See also
IPsec
SSL
Opportunistic encryption
Split tunneling
Intranet
Local Area Network
[edit] External links
JANET UK 'Different Flavours of VPN: Technology and Applications'
VPN Encryption
Virtual Private Network Consortium - trade association for VPN vendors
Microsoft TechNet VPN Resources
ZeroShell a small Linux distribution which is able to act as VPN box for LAN-to-LAN and host-to-LAN VPNs
Tutorial Using the Built-in Windows PPTP VPN Function
How Virtual Private Networks Work - A basic tutorial
OpenVPN Free cross platform VPN server/client
[edit] References
^ IP Based Virtual Private Networks,RFC 2764, B. Gleeson et al.,February2000
^ Generic Requirements for Provider Provisioned Virtual Private Networks (PPVPN),RFC3809, A. Nagarajan,June 2004
^ Provider Provisioned Virtual Private Network (VPN) Terminology,RFC4026, L. Andersson and T. Madsen,March 2005
^ BGP/MPLS VPNs,RFC 2547, E. Rosen & Y. Rekhter,March 1999
^ Address Allocation for Private Internets,RFC 1918, Y. Rekhter et al.,February 1996
^ A Core MPLS IP VPN Architecture,RFC 2918, K. Muthukrishnan& A. Malis,September 2000
^ Layer Two Tunneling Protocol "L2TP",RFC 2661, W. Townsley et al.,August 1999
^ IP Based Virtual Private Networks,RFC 2341, A. Valencia et al.,May 1998
^ Point-to-Point Tunneling Protocol (PPTP),RFC 2637, K. Hamzeh et al.,July 1999
Short history
روزي روزگاري دو فرشته کوچک در سفر بودند .
يک شب به منزل فردي ثروتمند رسيدند و از صاحبخانه اجازه خواستند تا شب را در آنجا سپري کنند . آن خانواده بسيار بي ادبانه برخورد کردند و اجازه نداند تا آن دو فرشته در اتاق ميهمانان شب را سپري کنند و در عوض آنها را به زيرزمين سرد و تاريکي منتقل کردند . آن دو فرشته کوچک همانطور که مشغول آماده کردن جاي خود بودند ناگهان فرشته بزرگتر چشمش به سوراخي در درون ديوار افتاد و سريعا به سمت سوراخ رفت و آنرا تعمير و درست کرد.
فرشته کوچکتر پرسيد : چرا سوراخ ديوار را تعمير کردي .
فرشته بزرگتر پاسخ داد : هميشه چيزهايي را که مي بينيم آنچه نيست که به نظر مي آيد .
فرشته کوچکتر از اين سخن سر در نياورد .
فردا صبح آن دو فرشته به راه خود ادامه دادند تا شب به نزديکي يک کلبه متعلق به يک زوج کشاورز رسيدند . و از صاحبخانه خواستند تا اجازه دهند شب را آنجا سپري کنند.
زن و مرد کشاورز که سني از آنها گذشته بود با مهرباني کامل جواب مثبت دادند و پس از پذيرايي اجازه دادند تا آن دو فرشته در اتاق آنها و روي تخت انها بخوابند و خودشان روي زمين سرد خوابيدند .
صبح هنگام فرشته کوچک با صداي گريه مرد و زن کشاورز از خواب بيدار شد و ديد آندو غرق در گريه مي باشند . جلوتر رفت و ديد تنها گاو شيرده آن زوج که محل درآمد آنها نيز بود در روي زمين افتاده و مرده .
فرشته کوچک برآشفت و به فرشته بزرگتر فرياد زد : چرا اجازه دادي چنين اتفاقي بيفتد . تو به خانواده اول که همه چيز داشتند کمک کردي و ديوار سوراخ آنها را تعمير کردي ولي اين خانواده که غير از اين گاو چيز ديگري نداشتند کمک نکردي و اجازه دادي اين گاو بميرد.
فرشته بزرگتر به آرامي و نرمي پاسخ داد : چيزها آنطور که ديده مي شوند به نظر نمي آيد.
فرشته کوچک فرياد زد : يعني چه من نمي فهمم.
فرشته بزرگ گفت : هنگامي که در زير زمين منزل آن مرد ثروتمند اقامت داشتيم ديدم که در سوراخ آن ديوار گنچي وجود دارد و چون ديدم که آن مرد به ديگران کمک نمي کند و از آنجه دارد در راه کمک استفاده نمي کند پس سوراخ ديوار را ترميم و تعمير کردم تا آنها گنج را پيدا نکنند .
ديشب که در اتاق خواب اين زوج خوابيده بودم فرشته مرگ آمد و قصد گرفتن جان زن کشاورز را داشت و من بجاي زن گاو را پيشنهاد و قرباني کردم .
چيزها آنطور که ديده مي شوند به نظر نمي آيند .
دوستان من : بعضي وقتها چيزهايي اتفاق مي افتد که دقيقا بر عکس انتظار و خواست ماست و اگر انصاف داريد به اتفاقاتي که مي افتد بايد اعتماد داشته باشيد . شايد که به وقت و زمانش متوجه دلايل آن اتفاقات شويد.
* آدمهايي به زندگي شما وارد مي شوند و به سرعت مي روند
* دوستاني پيدا مي شوند و مدتها باقي مي مانند و رد پايي زيبا در درون قلب ما باقي مي گذارند و ما خود اين کار را براي ديگران انجام نمي دهيم چون دوست خود را يافته ايم و ديگري اين کار را براي ما انجام داده.
* ديروز يک خاطره است ، فردا يک راز است و امروز يک هديه است . به همين دليل است که ما آنرا به زبان انگليسي Present يا هديه مي ناميم.
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زيباترين قلب
روزي مرد جواني وسط شهري ايستاده بود و ادعا مي كرد كه زيباترين قلب را در تمام آن منطقه دارد. جمعيت زيادي جمع شدند. قلب او كاملاً سالم بود و هيچ خدشه اي بر آن وارد نشده بود. پس همه تصديق كردند كه قلب او به راستي زيباترين قلبي است كه تاكنون ديده اند. مرد جوان، در كمال افتخار، با صدايي بلندتر به تعريف از قلب خود پرداخت. ناگهان پيرمردي جلو جمعيت آمد و گفت:اما قلب تو به زيبايي قلب من نيست؟ مرد جوان و بقيه جمعيت به قلب پيرمرد نگاه كردند. قلب او با قدرت تمام مي تپيد، اما پر از زخم بود. قسمتهايي از قلب او برداشته شده و تكه هايي جايگزين آنها شده بود؛ اما آنها به درستي جاهاي خالي را پر نكرده بودند و گوشه هايي دندانه دندانه در قلب او ديده مي شد. در بعضي نقاط شيارهاي عميقي وجودداشت كه هيچ تكه اي آنها را پر نكرده بود. مردم با نگاهي خيره به او مي نگريستند و با خود فكر مي كردند كه اين پيرمرد چطور ادعا مي كند كه قلب زيباتري دارد. مرد جوان به قلب پيرمرد اشاره كرد و خنديد و گفت:?تو حتماً شوخي مي كني....قلبت را با قلب من مقايسه كن. قلب تو، تنها مشتي زخم و خراش و بريدگي است.؟ پيرمرد گفت:?درست است، قلب تو سالم به نظر مي رسد، اما من هرگز قلبم را با قلب تو عوض نمي كنم. مي داني، هر زخمي نشانگر انساني است كه من عشقم را به او داده ام؛ من بخشي از قلبم را جدا كرده ام و به او بخشيده ام. گاهي او هم بخشي از قلب خود را به من داده است كه به جاي آن تكه بخشيده شده قرار داده ام. اما چون اين دو عين هم نبوده اند، گوشه هايي دندانه دندانه در قلبم دارم كه برايم عزيزند، چرا كه يادآور عشق ميان دو انسان هستند. بعضي وقتها بخشي از قلبم را به كساني بخشيده ام. اما آنها چيزي از قلب خود به من نداده اند. اينها همين شيارهاي عميق هستند. گرچه دردآورند، اما يادآور عشقي هستند كه داشته ام. اميدوارم كه آنها هم روزي بازگردند و اين شيارها عميق را با قطعه اي كه من در انتظارش بوده ام، پر كنند. پس حالا مي بيني كه زيبايي واقعي چيست؟؟ مرد جوان بي هيچ سخني ايستاد. در حالي كه اشك از گونه هايش سرازير مي شد به سمت پيرمرد رفت. از قلب جوان و سالم خود قطعه اي بيرون آورد و با دستهاي لرزان به پيرمرد تقديم كرد. پيرمرد آن را گرفت و در قلبش جاي داد و بخشي از قلب پير و زخمي خود را به جاي قلب مرد جوان گذاشت. مرد جوان به قلبش نگاه كرد؛ ديگر سالم نبود، اما از هميشه زيباتر بود. زيرا كه عشق، از قلب پيرمرد به قلب او نفوذ كرده بود.
فرستنده :مونا محبتي
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یک روز هزار سال
دو روز مانده به پايان جهان
تازه فهميد که هيچ زندگي نکرده است تقويمش پر شده بود و تنها دو روز
تنها دو روز خط نخورده باقي بود.
پريشان شد و آشفته و عصباني
نزد خدا رفت تا روزهاي بيشتري از خدا بگيرد.
داد زد و بد وبيراه گفت ،خدا سکوت کرد
جيغ کشيد و جار و جنجال راه انداخت
خدا سکوت کرد
آسمان و زمين را به هم ريخت
خدا سکوت کرد
به پر و پاي فرشته ها و انسان پيچيد
خدا سکوت کرد
کفر گفت و سجاده دور انداخت
خدا سکوت کرد
دلش گرفت و گريست و به سجاده افتاد
خدا سکوتش را شکست و گفت : عزيزم
اما يک روز ديگر هم رفت
تمام روز را به بد و بيراه و جار و جنجال از دست دادي
تنها يک روز ديگر باقي است
بيا و لااقل اين يک روز را زندگي کن
لا به لاي هق هقش گفت : اما با يک روز ؟
با يک روز چه کار مي توان کرد ؟
خدا گفت : آن کس که لذت يک روز زيستن را تجربه کند ، گويي که هزار سال زيسته است
و آنکه امروزش را در نمي يابد ، هزار سال هم به کارش نمي آيد
و آنگاه سهم يک روز زندگي را در دستانش ريخت و گفت
حالا برو و زندگي کن
او مات و مبهوت به زندگي نگاه کرد که در گوي دستانش مي درخشيد
اما مي ترسيد حرکت کند ، مي ترسيد راه برود ، مي ترسيد زندگي از لاي انگشتانش بريزد
قدري ايستاد
بعد با خودش گفت : وقتي فردايي ندارم ، نگه داشتن اين يک روز چه فايده ايي دارد
بگذار اين مشت زندگي را مصرف کنم
آن وقت شروع به دويدن کرد
زندگي را به سر و رويش پاشيد
زندگي را نوشيد و زندگي را بوييد
و چنان به وجد آمد
که ديد مي تواند تا ته دنيا بدود
مي تواند بال بزند
مي تواند
او درآن يک روز آسمان خراشي بنا نکرد ، زميني را مالک نشد ، مقامي را به دست نياورد
اما
اما درهمان يک روز دست بر پوست درخت کشيد ، روي چمن خوابيد
کفش دوزکي را تماشا کرد ، سرش را بالا گرفت و ابرها را ديد
و به آنها که او را نمي شناختند سلام کرد
و براي آنها که او را دوستش نداشتند از ته دل دعا کرد
او در همان يک روز آشتي کرد و خنديد و سبک شد
لذت برد و سرشار شد و بخشيد و عاشق شد و عبور کرد و تمام شد
او در همان يک روز زندگي کرد
اما فرشته ها در تقويم خدا نوشتند
امروز او در گذشت ، کسي که هزار سال زيسته بود
يک شب به منزل فردي ثروتمند رسيدند و از صاحبخانه اجازه خواستند تا شب را در آنجا سپري کنند . آن خانواده بسيار بي ادبانه برخورد کردند و اجازه نداند تا آن دو فرشته در اتاق ميهمانان شب را سپري کنند و در عوض آنها را به زيرزمين سرد و تاريکي منتقل کردند . آن دو فرشته کوچک همانطور که مشغول آماده کردن جاي خود بودند ناگهان فرشته بزرگتر چشمش به سوراخي در درون ديوار افتاد و سريعا به سمت سوراخ رفت و آنرا تعمير و درست کرد.
فرشته کوچکتر پرسيد : چرا سوراخ ديوار را تعمير کردي .
فرشته بزرگتر پاسخ داد : هميشه چيزهايي را که مي بينيم آنچه نيست که به نظر مي آيد .
فرشته کوچکتر از اين سخن سر در نياورد .
فردا صبح آن دو فرشته به راه خود ادامه دادند تا شب به نزديکي يک کلبه متعلق به يک زوج کشاورز رسيدند . و از صاحبخانه خواستند تا اجازه دهند شب را آنجا سپري کنند.
زن و مرد کشاورز که سني از آنها گذشته بود با مهرباني کامل جواب مثبت دادند و پس از پذيرايي اجازه دادند تا آن دو فرشته در اتاق آنها و روي تخت انها بخوابند و خودشان روي زمين سرد خوابيدند .
صبح هنگام فرشته کوچک با صداي گريه مرد و زن کشاورز از خواب بيدار شد و ديد آندو غرق در گريه مي باشند . جلوتر رفت و ديد تنها گاو شيرده آن زوج که محل درآمد آنها نيز بود در روي زمين افتاده و مرده .
فرشته کوچک برآشفت و به فرشته بزرگتر فرياد زد : چرا اجازه دادي چنين اتفاقي بيفتد . تو به خانواده اول که همه چيز داشتند کمک کردي و ديوار سوراخ آنها را تعمير کردي ولي اين خانواده که غير از اين گاو چيز ديگري نداشتند کمک نکردي و اجازه دادي اين گاو بميرد.
فرشته بزرگتر به آرامي و نرمي پاسخ داد : چيزها آنطور که ديده مي شوند به نظر نمي آيد.
فرشته کوچک فرياد زد : يعني چه من نمي فهمم.
فرشته بزرگ گفت : هنگامي که در زير زمين منزل آن مرد ثروتمند اقامت داشتيم ديدم که در سوراخ آن ديوار گنچي وجود دارد و چون ديدم که آن مرد به ديگران کمک نمي کند و از آنجه دارد در راه کمک استفاده نمي کند پس سوراخ ديوار را ترميم و تعمير کردم تا آنها گنج را پيدا نکنند .
ديشب که در اتاق خواب اين زوج خوابيده بودم فرشته مرگ آمد و قصد گرفتن جان زن کشاورز را داشت و من بجاي زن گاو را پيشنهاد و قرباني کردم .
چيزها آنطور که ديده مي شوند به نظر نمي آيند .
دوستان من : بعضي وقتها چيزهايي اتفاق مي افتد که دقيقا بر عکس انتظار و خواست ماست و اگر انصاف داريد به اتفاقاتي که مي افتد بايد اعتماد داشته باشيد . شايد که به وقت و زمانش متوجه دلايل آن اتفاقات شويد.
* آدمهايي به زندگي شما وارد مي شوند و به سرعت مي روند
* دوستاني پيدا مي شوند و مدتها باقي مي مانند و رد پايي زيبا در درون قلب ما باقي مي گذارند و ما خود اين کار را براي ديگران انجام نمي دهيم چون دوست خود را يافته ايم و ديگري اين کار را براي ما انجام داده.
* ديروز يک خاطره است ، فردا يک راز است و امروز يک هديه است . به همين دليل است که ما آنرا به زبان انگليسي Present يا هديه مي ناميم.
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زيباترين قلب
روزي مرد جواني وسط شهري ايستاده بود و ادعا مي كرد كه زيباترين قلب را در تمام آن منطقه دارد. جمعيت زيادي جمع شدند. قلب او كاملاً سالم بود و هيچ خدشه اي بر آن وارد نشده بود. پس همه تصديق كردند كه قلب او به راستي زيباترين قلبي است كه تاكنون ديده اند. مرد جوان، در كمال افتخار، با صدايي بلندتر به تعريف از قلب خود پرداخت. ناگهان پيرمردي جلو جمعيت آمد و گفت:اما قلب تو به زيبايي قلب من نيست؟ مرد جوان و بقيه جمعيت به قلب پيرمرد نگاه كردند. قلب او با قدرت تمام مي تپيد، اما پر از زخم بود. قسمتهايي از قلب او برداشته شده و تكه هايي جايگزين آنها شده بود؛ اما آنها به درستي جاهاي خالي را پر نكرده بودند و گوشه هايي دندانه دندانه در قلب او ديده مي شد. در بعضي نقاط شيارهاي عميقي وجودداشت كه هيچ تكه اي آنها را پر نكرده بود. مردم با نگاهي خيره به او مي نگريستند و با خود فكر مي كردند كه اين پيرمرد چطور ادعا مي كند كه قلب زيباتري دارد. مرد جوان به قلب پيرمرد اشاره كرد و خنديد و گفت:?تو حتماً شوخي مي كني....قلبت را با قلب من مقايسه كن. قلب تو، تنها مشتي زخم و خراش و بريدگي است.؟ پيرمرد گفت:?درست است، قلب تو سالم به نظر مي رسد، اما من هرگز قلبم را با قلب تو عوض نمي كنم. مي داني، هر زخمي نشانگر انساني است كه من عشقم را به او داده ام؛ من بخشي از قلبم را جدا كرده ام و به او بخشيده ام. گاهي او هم بخشي از قلب خود را به من داده است كه به جاي آن تكه بخشيده شده قرار داده ام. اما چون اين دو عين هم نبوده اند، گوشه هايي دندانه دندانه در قلبم دارم كه برايم عزيزند، چرا كه يادآور عشق ميان دو انسان هستند. بعضي وقتها بخشي از قلبم را به كساني بخشيده ام. اما آنها چيزي از قلب خود به من نداده اند. اينها همين شيارهاي عميق هستند. گرچه دردآورند، اما يادآور عشقي هستند كه داشته ام. اميدوارم كه آنها هم روزي بازگردند و اين شيارها عميق را با قطعه اي كه من در انتظارش بوده ام، پر كنند. پس حالا مي بيني كه زيبايي واقعي چيست؟؟ مرد جوان بي هيچ سخني ايستاد. در حالي كه اشك از گونه هايش سرازير مي شد به سمت پيرمرد رفت. از قلب جوان و سالم خود قطعه اي بيرون آورد و با دستهاي لرزان به پيرمرد تقديم كرد. پيرمرد آن را گرفت و در قلبش جاي داد و بخشي از قلب پير و زخمي خود را به جاي قلب مرد جوان گذاشت. مرد جوان به قلبش نگاه كرد؛ ديگر سالم نبود، اما از هميشه زيباتر بود. زيرا كه عشق، از قلب پيرمرد به قلب او نفوذ كرده بود.
فرستنده :مونا محبتي
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یک روز هزار سال
دو روز مانده به پايان جهان
تازه فهميد که هيچ زندگي نکرده است تقويمش پر شده بود و تنها دو روز
تنها دو روز خط نخورده باقي بود.
پريشان شد و آشفته و عصباني
نزد خدا رفت تا روزهاي بيشتري از خدا بگيرد.
داد زد و بد وبيراه گفت ،خدا سکوت کرد
جيغ کشيد و جار و جنجال راه انداخت
خدا سکوت کرد
آسمان و زمين را به هم ريخت
خدا سکوت کرد
به پر و پاي فرشته ها و انسان پيچيد
خدا سکوت کرد
کفر گفت و سجاده دور انداخت
خدا سکوت کرد
دلش گرفت و گريست و به سجاده افتاد
خدا سکوتش را شکست و گفت : عزيزم
اما يک روز ديگر هم رفت
تمام روز را به بد و بيراه و جار و جنجال از دست دادي
تنها يک روز ديگر باقي است
بيا و لااقل اين يک روز را زندگي کن
لا به لاي هق هقش گفت : اما با يک روز ؟
با يک روز چه کار مي توان کرد ؟
خدا گفت : آن کس که لذت يک روز زيستن را تجربه کند ، گويي که هزار سال زيسته است
و آنکه امروزش را در نمي يابد ، هزار سال هم به کارش نمي آيد
و آنگاه سهم يک روز زندگي را در دستانش ريخت و گفت
حالا برو و زندگي کن
او مات و مبهوت به زندگي نگاه کرد که در گوي دستانش مي درخشيد
اما مي ترسيد حرکت کند ، مي ترسيد راه برود ، مي ترسيد زندگي از لاي انگشتانش بريزد
قدري ايستاد
بعد با خودش گفت : وقتي فردايي ندارم ، نگه داشتن اين يک روز چه فايده ايي دارد
بگذار اين مشت زندگي را مصرف کنم
آن وقت شروع به دويدن کرد
زندگي را به سر و رويش پاشيد
زندگي را نوشيد و زندگي را بوييد
و چنان به وجد آمد
که ديد مي تواند تا ته دنيا بدود
مي تواند بال بزند
مي تواند
او درآن يک روز آسمان خراشي بنا نکرد ، زميني را مالک نشد ، مقامي را به دست نياورد
اما
اما درهمان يک روز دست بر پوست درخت کشيد ، روي چمن خوابيد
کفش دوزکي را تماشا کرد ، سرش را بالا گرفت و ابرها را ديد
و به آنها که او را نمي شناختند سلام کرد
و براي آنها که او را دوستش نداشتند از ته دل دعا کرد
او در همان يک روز آشتي کرد و خنديد و سبک شد
لذت برد و سرشار شد و بخشيد و عاشق شد و عبور کرد و تمام شد
او در همان يک روز زندگي کرد
اما فرشته ها در تقويم خدا نوشتند
امروز او در گذشت ، کسي که هزار سال زيسته بود
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