The Hacker's Encyclopedia 1998

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==Phrack Inc.== Volume Two, Issue 18, Phile #3 of 11 _ _ _ _ _____________________________________________ _ _ _ _ _-_-_-_- -_-_-_-_ _-_-_-_- An Introduction To -_-_-_-_ _-_-_-_- -_-_-_-_ _-_-_-_- Packet Switched Networks -_-_-_-_ _-_-_-_- -_-_-_-_ _-_-_-_- -_-_-_-_ _-_-_-_- -_-_-_-_ _-_-_-_- Written By - Revised - -_-_-_-_ _-_-_-_- -_-_-_-_ _-_-_-_- Epsilon 05/3/88 -_-_-_-_ _-_-_-_-_____________________________________________-_-_-_-_ Preface - In the past few years, Packet Switched Networks have become a prominent feature in the world of telecommunications. These networks have provided ways of communicating with virtually error-free data, over very large distances. These networks have become an imperative to many a corporation in the business world. In this file we will review some of the basic aspects of Packet Switched Networks. Advantages - The Packet Switched Network has many advantages to the common user, and even more to the hacker, which will be reviewed in the next topic. The basis of a Packet Switched Network is the Packet Switch. This network enables the service user to connect to any number of hosts via a local POTS dial-up/port. The various hosts pay to be connected to this type of network, and that's why there is often a surcharge for connection to larger public services like Compuserve or The Source. A Packet Switched Network provides efficient data transfer and lower rates than normal circuit switched calls, which can be a great convenience if you are planning to do a lot of transferring of files between you and the host. Not only is the communication efficient, it is virtually error free. Whereas in normal circuit switched calls, there could be a drastic increase in errors, thus creating a bad transfer of data. When using a Packet Switched Network, it is not important that you communicate at the same baud rate as your host. A special device regulates the speed so that the individual packets are sped up or slowed down, according to your equipment. Such a device is called a PAD (Packet Assembler Disassembler). A PSN also provides access to a variety of information and news retrieval services. The user pays nothing for these calls, because the connections are collect. Although the user may have to subscribe to the service to take advantage of it's services, the connection is usually free, except for a surcharge on some of the larger subscription services. Advantages To Hackers - Packet Switched Networks, to me, are the best thing to come along since the phone system. I'm sure many other hackers feel the same way. One of the reasons for this opinion is that when hacking a system, you need not dial out of your LATA, using codes or otherwise. Now, the hacker no longer has to figure out what parameters he has to set his equipment to, to communicate with a target computer effectively. All PSSes use the same protocol, set by international standards. This protocol is called X.25. This protocol is used on every network-to-network call in the world. When operating on a packet switch, you are not only limited to your own network (As if that wasn't enough already). You can access other PSSes or private data networks through gateways which are implemented in your PSN. There are gateways to virtually every network, from virtually every other network, except for extremely sensitive or private networks, in which case would probably be completely isolated from remote access. Another advantage with PSNs is that almost everyone has a local port, which means if you have an outdial (Next paragraph), you can access regular circuit switched hosts via your local Packet Switched Network port. Since the ports are local, you can spend as much time as you want on it for absolutely no cost. So think about it. Access to any feasible network, including overseas PSNs and packet switches, access to almost any host, access to normal circuit switched telephone-reachable hosts via an outdial, and with an NUI (Network User Identity - Login and password entered at the @ prompt on Telenet), unlimited access to any NUA, reverse-charged or not. Due to the recent abuse of long distance companies, the use of codes when making free calls is getting to be more and more hazardous. You may ask, 'Is there any resort to making free calls without using codes, and without using a blue box?' The answer is yes, but only when using data. With an outdial, accessible from your local PSN port, you can make data calls with a remote modem, almost always connected directly to a server, or a port selector. This method of communicating is more efficient, safer, and more reliable than using any code. Besides, with the implementation of equal access, and the elimination of 950 ports, what choice will you have? Some Important Networks - As aforementioned, PSNs are not only used in the United States. They are all over the place. In Europe, Asia, Canada, Africa, etc. This is a small summary of some of the more popular PSNs around the world. Country Network Name *DNIC ~~~~~~~ ~~~~~~~ ~~~~ ~~~~ Germany Datex-P 2624 Canada Datapac 3020 Italy Datex-P 0222 South Africa Saponet 0655 Japan Venus-P 4408 England Janet/PSS 2342 USA Tymnet 3106 USA Telenet 3110 USA Autonet 3126 USA RCA 3113 Australia Austpac 0505 Ireland Irepac 2724 Luxembourg Luxpac 2704 Singapore Telepac 5252 France Transpac 2080 Switzerland Telepac 2284 Sweden Telepac 2405 Israel Isranet 4251 ~~~~~~~~~ ~~~~~~~ ~~~~ * - DNIC (Data Network Identification Code) Precede DNIC and logical address with a '0' when using Telenet. ______________________________________________________________________________ Notes On Above Networks - Some countries may have more than one Packet Switching Network. The ones listed are the more significant networks for each country. For example, the United States has eleven public Packet Switching Networks, but the four I listed are the major ones. Several countries may also share one network, as shown above. Each country will have equal access to the network using the basic POTS dial-up ports. Focus On Telenet - Since Telenet is one of the most famous, and highly used PSNs in the United States, I thought that informing you of some of the more interesting aspects of this network would be beneficial. Interconnections With Other Network Types - Packet Switched Networks are not the only type of networks which connect a large capacity of hosts together. There are also Wide Area Networks, which operate on a continuous link basis, rather than a packet switched basis. These networks do not use the standardized X.25 protocol, and can only be reached by direct dial-ups, or by connecting to a host which has network access permissions. The point is, that if you wanted to reach, say, Arpanet from Telenet, you would have to have access to a host which is connected to both networks. This way, you can connect to the target host computer via Telenet, and use the WAN via the target host. WANs aren't the only other networks you can access. Also, connections to other small, private, interoffice LANs are quite common and quite feasible. Connections To International NUAs via NUIs - When using an NUI, at the prompt, type 0+DNIC+NUA. After your connection is established, proceed to use the system you've reached. Private Data Networks - Within the large Packet Switched Networks that are accessible to us there are also smaller private networks. These networks can sometimes be very interesting as they may contain many different systems. A way to identify a private network is by looking at the three digit prefix. Most prefixes accessible by Telenet are based on area codes. Private networks often have a prefix that has nothing to do with any area code. (Ex. 322, 421, 224, 144) Those prefixes are not real networks, just examples. Inside these private networks, there are often smaller networks which are connected with some type of host selector or gateway server. If you find something like this, there may be hosts that can be accessed only by this port selector/server, and not by the normal prefix. It is best to find out what these other addresses translate to, in case you are not able to access the server for some reason. That way, you always have a backup method of reaching the target system (Usually the addresses that are accessed by a gateway server/port selector translate to normal NUAs accessible from your Telenet port). When exploring a private network, keep in mind that since these networks are smaller, they would most likely be watched more closely during business hours then say Telenet or Tymnet. Try to keep your scanning and tinkering down to a minimum on business hours to avoid any unnecessary trouble. Remember, things tend to last longer if you don't abuse the hell out of them. Summary - I hope this file helped you out a bit, and at least gave you a general idea of what PSNs are used for, and some of the advantages of using these networks. If you can find something interesting during your explorations of PSNs, or Private Data Networks, share it, and spread the knowledge around. Definitely exploit what you've found, and use it to your advantage, but don't abuse it. If you have any questions or comments, you reach me on - The FreeWorld II/Central Office/Forgotten Realm/TOP. I hope you enjoyed my file. Thanks for your time. I should be writing a follow up article to this one as soon as I can. Stay safe.. - Epsilon ______________________________________________________________________________ - Thanks To - Prime Suspect/Sir Qix/The Technic/Empty Promise/The Leftist ______________________________________________________________________________