3-DES or RSA

By Raul Bernardino

Introduction:

Nowadays, in the global communication infrastructure is allowing everyone is connecting through the private networks in which have integrated with global networks such as internet and emails. With this global communication infrastructure is allowing almost everyone to communicate easily and effective in anytime and anywhere. More than 34% of the world populations are using the internet. The cross boarder communication and the virtual communication are becoming a concern of everyone on how to secure the communication and how to ensure those transactions are reaching to the right destination with the right information.

“Therefore, securing the communication is becoming a priority with the following properties; such as the confidentiality, end point authentication, message integrity, and operational security,” Kurose J. and Ross K., (2010, P. 714-715).

The confidentiality: The confidentiality perceives as secure communication. First, the sender has to understand the contain of the information that willing to transmit to the intent receiver. Second, the eavesdropper may be intercepting the messages. Therefore, the message has to be encrypted before it sends.

The end point authentication: The authentication means to confirm the identity of the both receiver and sender before transmitting the message. It is not simple authentication like face to face meeting. In the virtual situation it’s difficult to recognize. For instance, we got a message from the friend and maybe it is not coming from the intend person.

The message integrity: The integrity of the message is important, therefore, it is need to be rechecked with the sender if the message contain is correct even though the both receiver and sender are authenticated.

The operational security:  The security on the operational is important because almost all companies and other institutions are connecting their networks with the public network or internet. Therefore, we have to secure communication from the private to the public, because we did not know who is in the public network.

As it shows in below diagram:

There are several methods of encrypting the data communication such as triple DES (3DES) which is standing for Data Encryption Standard, AES which is standing for Advance Encryption Standard, and RSA. The “RSA algorithm are form from the names of the persons namely Ron Rivest, Adi Shamir, and Leonard Adleman,” Kurose J. and Ross K., (2010, P. 722-727). The diagram below shows the security association between two routers (R1 and R2).

 The R1 stores for SA as follows:

·        The security parameter index (SPI) uses 32 bit identifier

·        The interface of the source of security association is 200.168.1.100

·        The interface of the destination of security association is 193.68.2.23

·        The encryption types can be used such as 3 DES with cipher block chaining (CBC)

·        The key of the encryption

·        The  integrity check type such as MD5

·        The key of the authentication

In the SA Database (SAD) as follow:

·        During the process , the end point holding the state

·        If there is a VPN connections with n salespersons then 2 +2n SA in the R1 of the security association database

·        The sending of the IPsec datagram; the R1 is accessing the SAD in order to determine which and how to process datagram

·        Arrived in the R2, the R2 examines the SPI in the IPsec datagram and process datagram accordingly

The 3DES is using 64 bit of block and 56 key while the AES is using 128 bit of block. The AES can be operating in 128 bit, 196 bit, and 256 bit. The key algorithms determine in internal algorithms from mini table mapping and permutation. For instance n key length has 2ⁿ possible keys. “The 56 bit key of the DES is 2⁵⁶ possible keys and it can be crack in a second, and 128 bit key of AES can be crack in 149 trillion years,” Kurose J. and Ross K., (2010, P. 723). The Kaufman diagram table of the 64 bit as it show in the below table:

How to make DES more secure:

The 3DES has three times encryption with three different keys such as actual encrypt, decrypt, and encrypt.

The RSA has most similarity with public keys by using modulo n arithmetic as shows below:

Another RSA property is:

In September 2000, RSA claimed and patented in USA by Public Key Partner (PKP), Inc.

References list:

1. Kurose, J.F. & Ross, K.W. (2010) Computer Networking: A Top-Down Approach. 5^th ed. Boston: Addison Wesley
2. University of Liverpool/Laureate Online Education (2011) Lecture notes from Computer Networking Module Seminar 7 [Online]. Available from: University of Liverpool/Laureate Online Education VLE (Accessed: 9 September 2011)
3. Internet World Statistic, [Online]. Available from: http://www.internetworldstats.com/stats.htm  (Accessed:  25 August 2013)
4. Security in the Network, [Online]. Available from: http://www.informit.com/articles/article.aspx?p=31339&seqNum=2  (Accessed: 25 August 2013)
5. Symmetric vs. asymmetric algorithms, [Online]. Available from: http://www.suse.de/~garloff/Writings/mutt_gpg/node3.html (Accessed: 25 August 2013)
6.  Algorithms Used by SSH, [Online]. Available from: http://docstore.mik.ua/orelly/networking_2ndEd/ssh/ch03_09.htm (Accessed: 25 August 2013)

The PBX

By Raul Bernardino

Introduction:

Nowadays, the networks and internet technology is growing faster. The companies, organizations, governments, and the institutions are using these technologies to connect, communicate, coordinate and collaborate (four sees or 4Cs) in their information sharing among themselves or shared them between the public audiences within cross border information platforms’. The internet communication facility, allows everyone to share their expertise, experiences, knowledge, information, and also to be able to interact within one and another without having any limitation; the accessibility and reliability of the data sharing information and knowledge over networks are to ensure that everyone has same opportunity to access and convene same bits of the information. The information and knowledge has to be reliable and accessible at any time and from anywhere. Therefore, it is important enabling this trend of connectivity’s within an existing networks with internet telephony.  

“The real time interactive audio and video over internet is called internet telephone or internet video call. This is similar to the traditional telephone call which is using telephone circuit and switches”, Kurose J. and Ross K., (2010, P. 627). For example, establishes voice or video calls from PC to PC or from PC to the normal telephone switches voice calls. Other examples are using Skype to call from PC to PC or PC to normal telephone networks, net meeting, go to meeting, and other polycom products such as video and audio conferences.

The PBX stands for private branch exchange. That is a telephone system, where within one office shares the public switched telephone network (PSTN) lines. It can be one or more telephone lines that are coming from telecom provider to the office and the office is sharing those resources among the end users within one office or between branch offices. For instance, four PSTN lines from telecom operator to the office; these PSTN lines can be divided into one dedicates line for the official fax mail machine and other three PSTN lines are connected through the PBX trunks in which to ne shared within the rest of the team. One of PBX trunk shows in the below picture:

Each team member can be reached by extension phones. The extension phones, usually has two to four digits depends on the PBX configuration. The extension phones are also connected to the PBX trunks. One of extension as it shows in the below picture:

The extension phones are enabling team member to make a communication internally or establish a communication within branch offices without have any cost.

The PBX is referring to the PABX and EPABX. The PABX stands for private automatic branch exchange while EPABX stands electronic private automatic branch exchange.

Since 1990, there were developments in the PBX technology. They are focusing on the packet switching. The companies, organization, government, and institutions are using packet switched for the data communication. It attempts to use as telephone calls and later it calls VoIP (Voice over IP). The ISDN also another development in that time, whereas can make a conference call, call forwarding, and caller ids.

The technology between LAN and traditional telephone networks are PBX and router. These two technologies can become exchange switch from normal telephone call to the VoIP or from VoIP to normal telephone network.  For instance, by is using the Skype whereas to make a call from PC to PC or from PC to normal telephone network. The PBX has to add digital trunks in which to enable the connection between router and voice lines. As it shows in below diagram:

The PBX functions are as follows: To establish a communication between two parties or more and it is including ensuring that the line is free or busy. To maintain the connection as it require. To disconnect the connection as it require. To provide the information’s such as telephone bills.

References list:

1.     Kurose, J.F. & Ross, K.W. (2010) Computer Networking: A Top-Down Approach. 5^th ed. Boston: Addison Wesley

2.     Business telephone system, [Online]. Available from: http://en.wikipedia.org/wiki/Private_branch_exchange#Private_branch_exchange   (Accessed: 6 July 2013)

3.     Cisco 3640 Router - PBX Interoperability: Nortel Meridian Option 11 Rel. 24 PBX with Analog FXS and FXO interfaces to an MGCP Gateway, [Online]. Available from: http://www.cisco.com/en/US/docs/voice_ip_comm/cucme/pbx/interop/notes/210514nt.pdf (Accessed: 6 July 2013)

Intruder Alert

By Raul Bernardino

Introduction:

The “Domain Names Systems (DNSs) are supporting the internet infrastructure to resolve the host names to the internet protocol (IP) or from IP to the host names,” (Davidowicz, D. (1999). The function of the DNS is similar to the telephone directory, in which is helping human being to easily memorize the host names rather than computer numeric addresses. The fundamental functions of the DNS are follows:

• Forward resolution: The forward resolution known as translating from host name in to the IP address
• Inverse resolution: The inverse resolution known as translating the IP address in to the host name

Initial the DNS is designed with a security embedded. It is public database and not restricted of the accesses. Therefore, it is vulnerable and the bad guy can be intercepted the message, as it shows in the below diagram:

How DNS Poisoning happen?

First of all DNS resolves the query internally then if it is not found, the DNS server will be passing the query to the other servers. The following server may contain wrong information and replying to the requested server.  Here is the caching of the poison happened as it shows in below diagram:

The host-1 is willing to browse 'ourdns.example.org'. The local server has not have the answer. The local server then passing the query to the other server and other server responding with the 'brokendns.exemple.org' information. It is now cached in the local server. From now on, anyone from the same network that request or browse the address of 'ourdns.exemple.org' the local server will be giving the wrong information. Here, we called DNS cache poisoning. The attacker can be used this opportunity to establish communication with the host-1 as the victim.

The attacker intentional formulate misleading information with the rogue server name as it shows in  the below diagram:

 The established communication called spoofing of the host name.

How to prevent?

To prevent and minimized the DNS cache poisoning, the network administrators are adding firewall, proxy, Gateways, and Intrusion detection system.

The firewall is isolating a private network to the internet connection in which to allow several packets to pass through and also block several packets, as it show in the below diagram:

The gateway or router firewall: The gateway application functions as follows:

• Filtering the packets on the application data as well as on the TCP/IP/UDP
•  Allowing several internal users to use telnet to communicate outsider as it shows in the below diagram:

The intrusion detection system (IDS) as follows:

•  Filtering Packets: The packet filters are operation on the TCP or IP headers and it is not related to the check among session
• IDS: The IDS has a deep inspection to the packets such as to identify the strings with the antivirus data-base and attack string. It is also examining the related packets over port scanning, network mapping, and Denial of the service attack

As it is shows in the below diagram:

In conclusion: DNS is designed to be a public data-base and have no security embedded. Therefore, we have to configure our network with firewall or router firewalls whereas to minimized the attacks and prevent the spam’s or viruses going to our network.

References list:

1.  Kurose, J.F. & Ross, K.W. (2010) Computer Networking: A Top-Down Approach. 5^th ed. Boston: Addison Wesley
2. University of Liverpool/Laureate Online Education (2011) Lecture notes from Computer Networking Module Seminar 7 [Online]. Available from: University of Liverpool/Laureate Online Education VLE (Accessed: 16  September 2011)
3.  Security in the Network, [Online]. Available from: http://www.informit.com/articles/article.aspx?p=31339&seqNum=2  (Accessed: 17 September 2011)
4.  Davidowicz, D. (1999), Domain Name System, [Online]. Available from: http://compsec101.antibozo.net/papers/dnssec/dnssec.html  (Accessed: 17 September 2011)