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Monday 25 October 2010

Network Technology: Network Security: How to Configuring RIP Authentication

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

As my previous post about RIP Protocol, here this post I want to show you how to configure RIP Authentication...

Generally, There are two versions of Routing Information Protocol (RIP): version 1 and version 2. RIP version 1 does not support authentication of routing updates; however, RIP version 2 supports both plain text and MD5 authentication.

The Picture Figure below shows two routers, Router A and Router B, that exchange
RIP version 2 MD5 authentication updates.

Router A and Router B configured for RIP authentication


Configuring authentication of RIP version 2 updates is fairly easy and very uniform. The basic configuration includes the following steps:


1. Define the key chain using the command key−chain <> in global configuration mode. This command transfers you to the key chain configuration mode.

2. Specify the key number with the key <> command in key chain configuration mode.You can configure multiple keys.

3. For each key, identify the key string with the key−string <> command.

4. Configure the period for which the key can be sent and received. Use the following
commands:

accept−lifetime {infinite|end−time|duration −
seconds}
send−lifetime {infinite|end−time|duration seconds}


5. Exit key chain configuration mode with the exit command.

6. Under interface configuration mode, enable the authentication of RIP updates with this command:

ip rip authentication key−chain

This command is all that is needed to use plain text authentication.

7. Optionally, under interface configuration mode, enable MD5 authentication of RIP updates using the ip rip authentication mode md5 command.

The listings that follow show how Router A and Router B in Figure 1.3 should be configured to authenticate updates from one another using RIP MD5 authentication. Listing 1.1 shows the configuration of Router A, and Listing 1.2 shows the configuration of Router B.

Listing 1.1: Router A's configuration with MD5 authentication:

key chain systems
key 1
key−string router
!
interface Loopback0
ip address 10.10.10.1 255.255.255.0
!
interface Ethernet0/0
ip address 10.10.11.1 255.255.255.0
!
interface Serial0/0
ip address 192.168.10.1 255.255.255.252
ip rip authentication mode md5
ip rip authentication key−chain systems
clockrate 64000
!
router rip
version 2
network 10.0.0.0
network 192.168.10.0
no auto−summary

Listing 1.2: Router B's configuration with MD5 authentication:

key chain cisco
key 1
key−string router
!
interface Loopback0
ip address 10.10.12.1 255.255.255.0
!
interface FastEthernet0/0
ip address 10.10.13.1 255.255.255.0
!
interface Serial0/0
ip address 192.168.10.2 255.255.255.252
ip rip authentication mode md5
ip rip authentication key−chain cisco
!
router rip
version 2
network 10.0.0.0
network 192.168.10.0
no auto−summary

The configuration in Listing 1.1 displays Router A's MD5 configuration. Router A is configured with a key chain value of systems, a key value of 1, and a key−string value of router. Listing 1.2 displays Router B's MD5 configuration. Router B is configured with a key chain value of cisco, a key value of 1, and a key−string value of router.

Note Notice that the key−chain command of each router can have a different value; however, the key−string command must match for each key that is configured on each neighbor.

You can use the command debug ip rip to examine how RIP receives the encrypted routing updates. Entering this command on Router A and Router B displays the output shown in Listing 1.3 and Listing 1.4, respectively.


Listing 1.3: The output of the command debug ip rip displays how Router A receives RIP routing
updates from Router B:

Router−A#debug ip rip
RIP protocol debugging is on
Router−A#
RIP: received packet with MD5 authentication
RIP: received v2 update from 192.168.10.2 on Serial0/0
10.10.12.0/24 −> 0.0.0.0 in 1 hops
10.10.13.0/24 −> 0.0.0.0 in 1 hops

Listing 1.4: The output of the command debug ip rip displays how Router B receives RIP routing
updates from Router A:

Router−B#debug ip rip
RIP protocol debugging is on
Router−B#
RIP: received packet with MD5 authentication
RIP: received v2 update from 192.168.10.1 on Serial0/0
10.10.10.0/24 via 0.0.0.0 in 1 hops
10.10.11.0/24 via 0.0.0.0 in 1 hops



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Wednesday 22 September 2010

Network Technology: Network Security: Understanding OSI Network Layer- Model

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

The Open Systems Interconnection model (OSI model) is a product of the Open Systems Interconnection effort at the International Organization for Standardization. It is a way of sub-dividing a communications system into smaller parts called layers. A layer is a collection of conceptually similar functions that provide services to the layer above it and receives services from the layer below it. On each layer an instance provides services to the instances at the layer above and requests service from the layer below.

OSI Model Network Layers

For example, a layer that provides error-free communications across a network provides the path needed by applications above it, while it calls the next lower layer to send and receive packets that make up the contents of the path. Conceptually two instances at one layer are connected by a horizontal protocol connection on that layer.

Description of OSI layers:

Layer 1: Physical Layer

The Physical Layer defines the electrical and physical specifications for devices. In particular, it defines the relationship between a device and a transmission medium, such as a copper or optical cable. This includes the layout of pins, voltages, cable specifications, hubs, repeaters, network adapters, host bus adapters (HBA used in storage area networks) and more.

To understand the function of the Physical Layer, contrast it with the functions of the Data Link Layer. Think of the Physical Layer as concerned primarily with the interaction of a single device with a medium, whereas the Data Link Layer is concerned more with the interactions of multiple devices (i.e., at least two) with a shared medium. Standards such as RS-232 do use physical wires to control access to the medium.

The major functions and services performed by the Physical Layer are:

* Establishment and termination of a connection to a communications medium.
* Participation in the process whereby the communication resources are effectively shared among multiple users. For example, contention resolution and flow control.
* Modulation, or conversion between the representation of digital data in user equipment and the corresponding signals transmitted over a communications channel. These are signals operating over the physical cabling (such as copper and optical fiber) or over a radio link.

Parallel SCSI buses operate in this layer, although it must be remembered that the logical SCSI protocol is a Transport Layer protocol that runs over this bus. Various Physical Layer Ethernet standards are also in this layer; Ethernet incorporates both this layer and the Data Link Layer. The same applies to other local-area networks, such as token ring, FDDI, ITU-T G.hn and IEEE 802.11, as well as personal area networks such as Bluetooth and IEEE 802.15.4.

Layer 2: Data Link Layer

The Data Link Layer provides the functional and procedural means to transfer data between network entities and to detect and possibly correct errors that may occur in the Physical Layer. Originally, this layer was intended for point-to-point and point-to-multipoint media, characteristic of wide area media in the telephone system. Local area network architecture, which included broadcast-capable multiaccess media, was developed independently of the ISO work in IEEE Project 802. IEEE work assumed sublayering and management functions not required for WAN use. In modern practice, only error detection, not flow control using sliding window, is present in data link protocols such as Point-to-Point Protocol (PPP), and, on local area networks, the IEEE 802.2 LLC layer is not used for most protocols on the Ethernet, and on other local area networks, its flow control and acknowledgment mechanisms are rarely used. Sliding window flow control and acknowledgment is used at the Transport Layer by protocols such as TCP, but is still used in niches where X.25 offers performance advantages.

The ITU-T G.hn standard, which provides high-speed local area networking over existing wires (power lines, phone lines and coaxial cables), includes a complete Data Link Layer which provides both error correction and flow control by means of a selective repeat Sliding Window Protocol.

Both WAN and LAN service arrange bits, from the Physical Layer, into logical sequences called frames. Not all Physical Layer bits necessarily go into frames, as some of these bits are purely intended for Physical Layer functions. For example, every fifth bit of the FDDI bit stream is not used by the Layer.

WAN Protocol architecture

Connection-oriented WAN data link protocols, in addition to framing, detect and may correct errors. They are also capable of controlling the rate of transmission. A WAN Data Link Layer might implement a sliding window flow control and acknowledgment mechanism to provide reliable delivery of frames; that is the case for SDLC and HDLC, and derivatives of HDLC such as LAPB and LAPD.

IEEE 802 LAN architecture

Practical, connectionless LANs began with the pre-IEEE Ethernet specification, which is the ancestor of IEEE 802.3. This layer manages the interaction of devices with a shared medium, which is the function of a Media Access Control sublayer. Above this MAC sublayer is the media-independent IEEE 802.2 Logical Link Control (LLC) sublayer, which deals with addressing and multiplexing on multiaccess media.

While IEEE 802.3 is the dominant wired LAN protocol and IEEE 802.11 the wireless LAN protocol, obsolescent MAC layers include Token Ring and FDDI. The MAC sublayer detects but does not correct errors.

Layer 3: Network Layer

The Network Layer provides the functional and procedural means of transferring variable length data sequences from a source to a destination via one or more networks, while maintaining the quality of service requested by the Transport Layer. The Network Layer performs network routing functions, and might also perform fragmentation and reassembly, and report delivery errors. Routers operate at this layer—sending data throughout the extended network and making the Internet possible. This is a logical addressing scheme – values are chosen by the network engineer. The addressing scheme is not hierarchical.

Careful analysis of the Network Layer indicated that the Network Layer could have at least 3 sublayers: 1.Subnetwork Access - that considers protocols that deal with the interface to networks, such as X.25; 2.Subnetwork Dependent Convergence - when it is necessary to bring the level of a transit network up to the level of networks on either side; 3.Subnetwork Independent Convergence - which handles transfer across multiple networks. The best example of this latter case is CLNP, or IPv7 ISO 8473. It manages the connectionless transfer of data one hop at a time, from end system to ingress router, router to router, and from egress router to destination end system. It is not responsible for reliable delivery to a next hop, but only for the detection of errored packets so they may be discarded. In this scheme, IPv4 and IPv6 would have to be classed with X.25 as Subnet Access protocols because they carry interface addresses rather than node addresses.

A number of layer management protocols, a function defined in the Management Annex, ISO 7498/4, belong to the Network Layer. These include routing protocols, multicast group management, Network Layer information and error, and Network Layer address assignment. It is the function of the payload that makes these belong to the Network Layer, not the protocol that carries them.

Layer 4: Transport Layer

The Transport Layer provides transparent transfer of data between end users, providing reliable data transfer services to the upper layers. The Transport Layer controls the reliability of a given link through flow control, segmentation/desegmentation, and error control. Some protocols are state and connection oriented. This means that the Transport Layer can keep track of the segments and retransmit those that fail. The Transport layer also provides the acknowledgement of the successful data transmission and if no error free data was transferred then sends the next data.

Although not developed under the OSI Reference Model and not strictly conforming to the OSI definition of the Transport Layer, typical examples of Layer 4 are the Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

Of the actual OSI protocols, there are five classes of connection-mode transport protocols ranging from class 0 (which is also known as TP0 and provides the least features) to class 4 (TP4, designed for less reliable networks, similar to the Internet). Class 0 contains no error recovery, and was designed for use on network layers that provide error-free connections. Class 4 is closest to TCP, although TCP contains functions, such as the graceful close, which OSI assigns to the Session Layer. Also, all OSI TP connection-mode protocol classes provide expedited data and preservation of record boundaries, both of which TCP is incapable. Detailed characteristics of TP0-4 classes are shown in the following table:


Perhaps an easy way to visualize the Transport Layer is to compare it with a Post Office, which deals with the dispatch and classification of mail and parcels sent. Do remember, however, that a post office manages the outer envelope of mail. Higher layers may have the equivalent of double envelopes, such as cryptographic presentation services that can be read by the addressee only. Roughly speaking, tunneling protocols operate at the Transport Layer, such as carrying non-IP protocols such as IBM's SNA or Novell's IPX over an IP network, or end-to-end encryption with IPsec. While Generic Routing Encapsulation (GRE) might seem to be a Network Layer protocol, if the encapsulation of the payload takes place only at endpoint, GRE becomes closer to a transport protocol that uses IP headers but contains complete frames or packets to deliver to an endpoint. L2TP carries PPP frames inside transport packet.

Layer 5: Session Layer

The Session Layer controls the dialogues (connections) between computers. It establishes, manages and terminates the connections between the local and remote application. It provides for full-duplex, half-duplex, or simplex operation, and establishes checkpointing, adjournment, termination, and restart procedures. The OSI model made this layer responsible for graceful close of sessions, which is a property of the Transmission Control Protocol, and also for session checkpointing and recovery, which is not usually used in the Internet Protocol Suite. The Session Layer is commonly implemented explicitly in application environments that use remote procedure calls.

Layer 6: Presentation Layer

The Presentation Layer establishes context between Application Layer entities, in which the higher-layer entities may use different syntax and semantics if the presentation service provides a mapping between them. If a mapping is available, presentation service data units are encapsulated into session protocol data units, and passed down the stack.

This layer provides independence from data representation (e.g., encryption) by translating between application and network formats. The presentation layer transforms data into the form that the application accepts. This layer formats and encrypts data to be sent across a network. It is sometimes called the syntax layer.[citation needed]

The original presentation structure used the basic encoding rules of Abstract Syntax Notation One (ASN.1), with capabilities such as converting an EBCDIC-coded text file to an ASCII-coded file, or serialization of objects and other data structures from and to XML.

Layer 7: Application Layer

The Application Layer is the OSI layer closest to the end user, which means that both the OSI application layer and the user interact directly with the software application. This layer interacts with software applications that implement a communicating component. Such application programs fall outside the scope of the OSI model. Application layer functions typically include identifying communication partners, determining resource availability, and synchronizing communication. When identifying communication partners, the application layer determines the identity and availability of communication partners for an application with data to transmit. When determining resource availability, the application layer must decide whether sufficient network or the requested communication exist. In synchronizing communication, all communication between applications requires cooperation that is managed by the application layer. Some examples of application layer implementations include Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Simple Mail Transfer Protocol (SMTP) and X.400 Mail.


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All about Love: http://visa-love.blogspot.com/
Learning English Online: http://visa-elb.blogspot.com/
Discovery Internet: http://visa-isp.blogspot.com/

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Thursday 9 September 2010

Network Technology: Network Security: Learning About RIP (Routing Information Protocol)

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

The Routing Information Protocol (RIP) is a dynamic routing protocol used in local and wide area networks. As such it is classified as an interior gateway protocol (IGP). It uses the distance-vector routing algorithm. It was first defined in RFC 1058 (1988). The protocol has since been extended several times, resulting in RIP Version 2 (RFC 2453). Both versions are still in use today, however, they are considered to have been made technically obsolete by more advanced techniques such as Open Shortest Path First (OSPF) and the OSI protocol IS-IS. RIP has also been adapted for use in IPv6 networks, a standard known as RIPng (RIP next generation), published in RFC 2080 (1997).

The routing algorithm used in RIP, the Bellman-Ford algorithm, was first deployed in a computer network in 1967, as the initial routing algorithm of the ARPANET.

The earliest version of the specific protocol that became RIP was the Gateway Information Protocol, part of the PARC Universal Packet internetworking protocol suite, developed at Xerox Parc. A later version, named the Routing Information Protocol, was part of Xerox Network Systems.

A version of RIP which supported the Internet Protocol (IP) was later included in the Berkeley Software Distribution (BSD) of the Unix operating system. It was known as the routed daemon. Various other vendors would create their own implementations of the routing protocol. Eventually, RFC 1058 unified the various implementations under a single standard.

RIP is a distance-vector routing protocol, which employs the hop count as a routing metric. The hold down time is 180 seconds. RIP prevents routing loops by implementing a limit on the number of hops allowed in a path from the source to a destination. The maximum number of hops allowed for RIP is 15. This hop limit, however, also limits the size of networks that RIP can support. A hop count of 16 is considered an infinite distance and used to deprecate inaccessible, inoperable, or otherwise undesirable routes in the selection process.

RIP implements the split horizon, route poisoning and holddown mechanisms to prevent incorrect routing information from being propagated. These are some of the stability features of RIP. It is also possible to use the so called RIP-MTI (Minimal Topology Information) algorithm to cope with the count to infinity problem. With its help, it is possible to detect every possible loop with a very small computation effort.

Originally each RIP router transmitted full updates every 30 seconds. In the early deployments, routing tables were small enough that the traffic was not significant. As networks grew in size, however, it became evident there could be a massive traffic burst every 30 seconds, even if the routers had been initialized at random times. It was thought, as a result of random initialization, the routing updates would spread out in time, but this was not true in practice. Sally Floyd and Van Jacobson showed in 1994 that, without slight randomization of the update timer, the timers synchronized over time. In most current networking environments, RIP is not the preferred choice for routing as its time to converge and scalability are poor compared to EIGRP, OSPF, or IS-IS (the latter two being link-state routing protocols), and (without RIP-MTI) a hop limit severely limits the size of network it can be used in. However, it is easy to configure, because RIP does not require any parameters on a router unlike other protocols.

RIP is implemented on top of the User Datagram Protocol as its transport protocol. It is assigned the reserved port number 520.

RIP Versions:

There are three versions of the Routing Information Protocol: RIPv1, RIPv2, and RIPng.

RIP version 1

The original specification of RIP, defined in RFC 1058, uses classful routing. The periodic routing updates do not carry subnet information, lacking support for variable length subnet masks (VLSM). This limitation makes it impossible to have different-sized subnets inside of the same network class. In other words, all subnets in a network class must have the same size. There is also no support for router authentication, making RIP vulnerable to various attacks.The RIP version 1 works when there is only 16 hop counts(0-15).If there are more than 16 hops between two routers it fails to send data packets to the destination address.

RIP version 2

Due to the deficiencies of the original RIP specification, RIP version 2 (RIPv2) was developed in 1993 and last standardized in 1998. It included the ability to carry subnet information, thus supporting Classless Inter-Domain Routing (CIDR). To maintain backward compatibility, the hop count limit of 15 remained. RIPv2 has facilities to fully interoperate with the earlier specification if all Must Be Zero protocol fields in the RIPv1 messages are properly specified. In addition, a compatibility switch feature allows fine-grained interoperability adjustments.

In an effort to avoid unnecessary load on hosts that do not participate in routing, RIPv2 multicasts the entire routing table to all adjacent routers at the address 224.0.0.9, as opposed to RIPv1 which uses broadcast. Unicast addressing is still allowed for special applications.

(MD5) authentication for RIP was introduced in 1997.

RIPv2 is Internet Standard STD-56.

Route tags were also added in RIP version 2. This functionality allows for routes to be distinguished from internal routes to external redistributed routes from EGP protocols.

RIPng

RIPng (RIP next generation), defined in RFC 2080,[8] is an extension of RIPv2 for support of IPv6, the next generation Internet Protocol. The main differences between RIPv2 and RIPng are:

* Support of IPv6 networking.
* While RIPv2 supports RIPv1 updates authentication, RIPng does not. IPv6 routers were, at the time, supposed to use IPsec for authentication.
* RIPv2 allows attaching arbitrary tags to routes, RIPng does not;
* RIPv2 encodes the next-hop into each route entries, RIPng requires specific encoding of the next hop for a set of route entries.xxx

...

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Friday 23 July 2010

Top Five Network Security Concerns You Should Learn

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!


Top Five Network Security Concerns You Should Learn

Getting into establishing a stable network is one concert. After the network already built is another one concern. The concern is about the Security. To keep network run stable and available, the network need to be secured.

Here's the Top 5 Network Security Concerns You Should Learn...

Visit here...

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Sunday 30 May 2010

Configuring SNMP Security

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

There is no specific command that you use to enable SNMP. To configure SNMP support, perform the tasks described in the following steps, only the first two steps are mandatory:

1.Enable the SNMP community string to define the relationship between the network
management station and the agent with the following command:

snmp−server community {ro|rw} {number}

The number value references an optional access−list.

2.Use this command to configure the router to send traps to an NMS host:

snmp−server host host [version {1|2c}]


3.Configure the type of traps for which a notification is sent to the NMS. You do so with the following command:

snmp−server enable traps [notification type] –
[notification option]

4.Set the system contact, location, and serial number. You can set the systems contact with the snmp−server contact [text] command. You set the location with the snmp−server location [text] command, and you set the serial number with the snmp−server chassis−id [text] command.

5.Use the access−list command to specify a list of hosts that are allowed read−, read/write, or write−only access to the router.

The picture below: shows Router 1, which is configured to allow SNMP read−only access and read/write access from two separate hosts. Router 1 is also configured to send SNMP trap information to the same two hosts. The following lines show how Router 1 should be configured so SNMP access from both host 192.168.10.1 and 192.168.10.2 is allowed and SNMP trap information is sent to both hosts:

access−list 12 permit 192.168.10.1
access−list 13 permit 192.168.10.2
snmp−server contact VISA
snmp−server location Network Engineers
snmp−server chassis−id 200000444
snmp−server community observe RO 12
snmp−server community adjust RW 13
snmp−server host 192.168.10.1 observe snmp
snmp−server host 192.168.10.2 adjust snmp


Router 1 configured for SNMP

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Saturday 24 April 2010

Hey, Your Facebook ID was HACKED?

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

Facebook is one of the most popular social networking sites that people use to connect each other. Each person needs to have a unique Facebook ID to Login to their account. What's UP if your facebook ID was Hacked? The Hacker will use your ID to do what they want.



I'm really concerned about that because I'm also using Facebook for networking with my friends.

According to The Network World, 1.5 million Facebook IDs were stolen and were ready up for sale. More about Facebook IDs were stolen and up for Sale Read here...

To make sure that your ID was hacked or not. Check any strange activities that may happen on your Facebook account that were not done by you...

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Monday 22 February 2010

How to Configuring Banner Messages on Cisco Router

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

My Previous Post: About How to Configuring Password Encryption on Cisco Router
This post: About How to Configuring Banner Messages on Cisco Router:

There are four types of banner messages:


---> Message of the Day (MOTD): Displayed at login. Useful for sending messages that affect all network users.
---> Login: Displayed after the Message of the Day banner appears and before the login
prompts.
---> EXEC: Displayed whenever an EXEC process is initiated.
---> Incoming: Displayed on terminals connected to reverse Telnet lines.

The process for configuring banner messages is fairly simple. Enter the following command in global configuration mode:

banner {exec|motd|login|incoming} [delimited character] –
[delimited character]


Here is a sample MOTD banner:

CiscoRouter#config t
Enter configuration commands, one per line. End with CNTL/Z.
CiscoRouter(config)#banner motd #
Enter TEXT message. End with the character '#'.
*****************************************************
* WARNING...WARNING...WARNING...WARNING
* YOU HAVE ACCESSED A RESTRICTED DEVICE
* USE OF THIS DEVICE WITHOUT PRIOR AUTHORIZATION
* OR FOR PURPOSES WHICH AUTHORIZATION HAS NOT BEEN
* GRANTED IS STRICTLY PROHIBITED!!!
*****************************************************
#
CiscoRouter(config)#end
CiscoRouter#


The results of setting the MOTD banner message can be seen by using the show running−config command or by logging into the router. The following is an example of logging into the router from the console port:

CiscoRouter con0 is now available
......
Press RETURN to get started.
......
******************************************************
* WARNING...WARNING...WARNING...WARNING
* YOU HAVE ACCESSED A RESTRICTED DEVICE
* USE OF THIS DEVICE WITHOUT PRIOR AUTHORIZATION
* OR FOR PURPOSES WHICH AUTHORIZATION HAS NOT BEEN
* GRANTED IS STRICTLY PROHIBITED!!!
******************************************************
CiscoRouter>


EXEC banner messages, as mentioned earlier, are invoked when a user attempts to gain access into privileged mode. Industry−standard best practices recommend configuring a MOTD banner message as well as an EXEC banner message. Working still on the same router, here's how to configure an EXEC banner to complement the MOTD banner. This can be accomplished using the following configuration:

CiscoRouter#config t
Enter configuration commands, one per line. End with CNTL/Z.
CiscoRouter(config)#banner exec #
Enter TEXT message. End with the character '#'.
*******************************************************
* WARNING...WARNING...WARNING...WARNING
* THIS IS A REMINDER...THIS IS A REMINDER
* YOU HAVE ACCESSED A RESTRICTED DEVICE
* USE OF THIS DEVICE WITHOUT PRIOR AUTHORIZATION
* OR FOR PURPOSES WHICH AUTHORIZATION HAS NOT BEEN
* GRANTED IS STRICTLY PROHIBITED!!!
*******************************************************
#
CiscoRouter(config)#end
CiscoRouter#


The results of setting the EXEC message can be seen by using the show running−config
command or by using the telnet command to remotely connect to a router with the EXEC banner enabled. The results of configuring both the MOTD banner and the EXEC banner can be seen here:

R1#telnet 192.168.10.1
Trying 192.168.10.1 ... Open
*******************************************************
* WARNING...WARNING...WARNING...WARNING
* YOU HAVE ACCESSED A RESTRICTED DEVICE
* USE OF THIS DEVICE WITHOUT PRIOR AUTHORIZATION
* OR FOR PURPOSES WHICH AUTHORIZATION HAS NOT BEEN
* GRANTED IS STRICTLY PROHIBITED!!!
23
*******************************************************
User Access Verification
Username: Visa
Password:
*******************************************************
* WARNING...WARNING...WARNING...WARNING
* THIS IS A REMINDER...THIS IS A REMINDER
* YOU HAVE ACCESSED A RESTRICTED DEVICE
* USE OF THIS DEVICE WITHOUT PRIOR AUTHORIZATION
* OR FOR PURPOSES WHICH AUTHORIZATION HAS NOT BEEN
* GRANTED IS STRICTLY PROHIBITED!!!
*******************************************************
CiscoRouter>en
Password:
CiscoRouter#


Notice that the EXEC banner is displayed after the user has passed the local authentication phase on the router.

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Monday 8 February 2010

How to Configuring Password Encryption

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

As my previous post about How to Configure Privilege Levels for Users on Cisco Router.
Today this post I'd like to show you how to configure Password Encryption on Cisco Router.

Well, It's relatively simple to configure password encryption on Cisco routers. When password encryption is configured, all passwords that are configured on the router are converted to an unsophisticated reversible cipher. Although the algorithm that is used to convert the passwords is somewhat unsophisticated, it still serves a very good purpose. Intruders cannot simply view the password in plain text and know what the password is. To enable the use of password encryption, use the command service password−encryption.

The following example shows a router configuration prior to enabling password encryption. An enable password, a console password, and a Telnet password is configured:

CiscoRouter#show running−config
!
enable password Cisco
!
line con 0
password NetVisa
!
line vty 0 4
password Security
!

The following example shows the command you would use to enable password encryption on the router:

CiscoRouter#config t
Enter configuration commands, one per line. End with CNTL/Z.
CiscoRouter(config)#service password−encryption
CiscoRouter(config)#end
CiscoRouter#
The results of enabling password encryption can be seen in the following example. Notice that each
password is now represented by a string of letters and numbers, which represents the encrypted format of the password:

CiscoRouter#show running−config
!
enable password 7 05280F1C2243
!
line con 0
password 7 04750E12182E5E45001702
!
line vty 0 4
password 7 122A00140719051033
!


Note: Password encryption does not provide a very high level of security. There are widely available passwords crackers that can reverse the encryption. I do, however, recommend using the password encryption command on all routers. I also recommend that you take additional security measures to protect your passwords.

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Monday 25 January 2010

How to Configure Privilege Levels for Users on Cisco Router

This blog is created for network security review, study and understanding about network related issues only! The blog is mainly focus on Network Security Notes about Network, Network Security, Network Technology, Network Labs review related Cisco and Microsoft technology ,Network Threats, Types of Network Threats, Network Alerts, Enterprise Security Policy and Audits, Security Policy and Audits,Logical Security, Physical and Logical Security, Physical Security,Cisco Products Review, Microsoft Products review, Cisco Routers, Routers Security, Console Access, Telnet Access, Network Attack, Network Attack report, Network management, Anti-virus, Network Security with Anti-virus, and All About Network Security... Thanks for your visit!

As my previous post about Disabling Password Recovery on Cisco Router. Today, with this post, I'd love to show you the way to Configure Privilege Levels for Users on Cisco Router.

Commands entered into the IOS can be associated with each privilege level. You
configure the privilege level for a command using the global configuration command privilege
level . The exact syntax of this command is as follows:

privilege mode level level command | reset command

The Image.1 below displays three users, Googla, Visa, and Yaha, connected to a local segment. Googla is the network engineer; he has full control over Cisco Router. Visa and Yaha are system administrators; they need only limited functionality on Cisco Router. Here is an example of the configuration that meets this requirement:

enable secret Googla
enable secret level 3 Visa
enable secret level 2 Yaha
privilege exec level 3 debug
privilege exec level 3 show running−config
privilege exec level 3 telnet
privilege exec level 2 ping
privilege exec level 2 sh int ser0
privilege exec level 2 sh ip route
line con 0
login
Figure
Image.1: Using privilege levels to create administrative levels.

This configuration provides Googla with the default full administrative rights to the router. Visa is given access to all features that are allowed with administrative level 3 and can perform the commands that are listed with a privilege level of 3. Yaha is assigned a privilege level of 2 and is given access to all features and allowed to perform the commands listed with a privilege level of 2.

The key is that each user must use the enable command from the user mode prompt and log in with the password assigned for that level. An example is provided here:

CiscoRouter>
CiscoRouter>enable 3
Password: Visa
CiscoRouter#



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