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Using telnet to connect from one computer to another is easy with this software

Using telnet to connect from one computer to another is easy with this software

Vote: (150 votes)

Program license: Free

Developer: Simon Tatham

Version: 0.80

Works under: Windows

Also available for Mac

Vote:

Program license

(150 votes)

Free

Developer

Version

Simon Tatham

0.80

Works under:

Also available for

Windows

Mac

Pros

  • Works with IPv6 connections
  • Runs as fast as the remote server sends packets
  • Supports running services over raw sockets
  • Emulates xterm control sequences
  • Can act like a VT102 or VT220 terminal if needed

Cons

  • No support for session tabs
  • Telnet connections are unsafe by design
  • Complicated command structure

PuTTY is a dedicated terminal emulator that can also transfer entire files over a computer network. It offers users support for a dizzying array of different network protocol services. These include common ones like secure shell and telnet as well as the Berkeley r-commands. Users are free to configure it to emulate a number of different physical terminals when needed.

In a majority of situations, the default settings will allow connections to whatever remote network someone is trying to reach. Those who are running graphical Unix software on the other end of the connection can tell PuTTY to act just like the classic xterm application regardless of the fact that they're running on Microsoft Windows. Whenever PuTTY runs in this mode, users have full access to the control sequences offered by the xterm specification. They can use their control key the same way they would if they were sitting in front of a GNU/Linux or FreeBSD box since PuTTY traps these keyboard sequences.

Perhaps more important is the fact that PuTTY can emulate physical VT102 and VT220 terminal boxes, which are some of the DEC machines that xterm is itself designed to emulate. An average VT120 unit might have had an integrated Intel 8080 microprocessor and a small amount of onboard RAM. Considering that the machines users are likely to run PuTTY on have far more system resources than these smart terminals ever did, the software doesn't really add any overhead to the emulation process.

Though it certainly supports a much wider feature set than real DEC terminals would have, PuTTY sends out all of its control codes in such a way that a remote computer wouldn't be able to distinguish between the two. Modern servers are seldom that particular about whether or not their clients comply with an arbitrary standard that stretches back to 1978 if not earlier. Therefore, PuTTY does allow users to violate these guidelines and make some text formatting changes that wouldn't be permissible under a strict interpretation.

System administrators will usually know what type of configuration they should use when accessing a remote computer, but it's easy enough to play around with the app's settings should it be necessary to experiment. Everything is controlled from a small window, so it's easy to make changes whenever somebody wants. In theory, you could even do so while a connection is still open though this can cause remote software applications to throw out error messages.

Color terminal support is baked into the application's display subroutines, so you won't have to worry about only ever sending out glass teletype codes. That being said, those who need to emulate the most basic types of devices are free to do so. Color customization options make it possible to still see the app as something other than merely a black on white screen.

All the color options you'd expect from a command line window are here, so you can paint your terminal window without actually sending any ANSI escape sequences to the computer on the other end of your connection. Those who have to provide server support late into the night hours will certainly appreciate the ability to select a black background. Hackers, phreaks and makers who want to really feel like they're getting into the part can even set the foreground text to glow green or cyan.

Long-time users might even want to try and capture the look of some vintage 8-bit computers or the terminals found on certain specialized Linux distros. PuTTY offers all of the tools necessary to do so. It also gives you everything you'd need to connect directly to a raw socket without passing data over a real dedicated protocol. That's important for those running complicated tests or who have to build their own network equipment for whatever reason. It's also a quick way to make sure that a serial cable is working as intended.

Like any terminal emulator, PuTTY can be rather terse at times. Whenever you're connected to a remote server, you're at the whims of whatever kind of software runs on it. If you're unfamiliar with its command structure, then there's nothing that the app itself can do to help you. On top of this, those who are connected over a telnet stream won't enjoy the benefits of any sort of modern security scheme since the technology first came into service back in 1969.

More than likely, the biggest drawback experienced PuTTY users are going to run into is the lack of support for dedicated session tabs. Without a tabbed document interface, you're going to end up having to open multiple PuTTY windows in order to manage multiple outside connections. This isn't necessarily a deal breaker for those who are interested in the advanced features that the software has to offer, but it can get annoying for those who have to work with a series of remote connections at the same time.

Secure shell protocol support more than makes up for many of these shortcomings. Countless devices now use this encrypted transport layer, which helps to ensure at least a modicum of safety between the two ends of the connection. PuTTY is fully compliant with the SSH specification and can perform a handshake with a remote server, which helps to sync the local client with a distant connection.

User authentication protocol tools are built into the ssh function, so those who are virtually dialing into a more sophisticated device can enjoy all of the features that this kind of connectivity has to offer. Built-in opcode will help to multiplex encrypted ssh data tunnels into a series of separate logical channels that function as though they were real dedicated spaces. Those who want something simpler than this can actually connect another machine via a conventional RS-232 serial port and pass packets over it easily.

Hardware that send bits in and out of a data channel in sequence work perfectly fine with PuTTY provided that you have the right drivers to let Windows access it. As long as the operating system can see whatever peripheral you have plugged into a serial port, PuTTY can at least try to create a connection over it. Most direct lines will work, though PuTTY may balk at dedicated old school modem hardware since it lacks proprietary drivers for these devices.

Then again, this isn't a dialer and it's unlikely that most people who plan on using something like PuTTY is going to do much dialing anyway. There's a high probability that they'll instead want to connect to systems over some form of Internet protocol, for which the app is ideal. A few additional features make it particularly useful for this kind of application. Perhaps the most important of these are related to data hashing, since they're needed for establishing a secure handshake that can't otherwise be captured.

Various ciphers like 3DES and RC4 come included with the software as does the option of creating a public key authentication system. These are going to be useful for those who want to share information over a network pathway without running the risk that someone might start to snoop on them. It also features support for a special key format file, which is called PPK. These are secured by an open-source message authentication code that's constantly being reviewed for any additional bugs that might show up in the wild. Blowfish and other conventional systems also receive a healthy amount of support, thus making it possible to use PuTTY in a variety of commercial situations. All of these ciphers have been checked by the developers to ensure compliance with their latest versions.

Ironically, it might be gamers and coders who get the most use out of PuTTY. There's been a recent uptick in the number of bulletin board systems posted online. Anyone who wants to access one of these needs a terminal emulator and PuTTY comes with everything they'd need to log into one of these services. Those who have account credentials can pass these through PuTTY and access secured remote storage systems. Once they're there, most users will find that sharing files and posting messages isn't difficult at all.

Others may want to employ PuTTY as a platform for running multi-user dungeons or shared hallucinations online. These are sophisticated text-only roleplaying games that are normally deployed over telnet. While they might not be secured, they've become increasingly popular over the years and PuTTY includes all of the features necessary to access them.

Unix hackers who are bound to Windows machines can take advantage of the inclusion of X11 forwarding technology, which makes it possible to send remote commands to graphical applications. X Windows is an environment that's completely different than Microsoft Windows, in spite of the name. By offering this support, PuTTY has helped to close the gap between these two systems that are otherwise only historically related to one another.

Terminals compliant with the ECMA-48 standard aren't as common as some of the other ones that PuTTY emulates, though these too can be simulated without letting a remote machine even realize that a person isn't sitting behind an actual glass screen. That's particularly useful for those who have to virtually access European-style online services and need to do so from their PC.

Several components come bundled with the PuTTY installer. While the rlogin, SSH and telnet clients are going to be the most popular of these, it also includes a command-line service that can unlock secure file copy transfer codes and send files over SFTP. A general file transfer utility is also included along with a standalone application called Plink. This acts as another CLI tool that enables users to slice directly into PuTTY backends. Documentation included with the software recommends that users always turn this app on when they want to tunnel traffic through a distant SSH connection layer.

Pageant is another standalone tool that comes with PuTTY and it can work as a dedicated authentication agent for both the telnet client as well as Plink. Those who need to make their own keys can access an included key generation utility that works with EdDSA codes as well as the original DSA system. More popular options, like RSA and ECDSA, ar also offered for those who don't have any need to deal with edge cases.

Information technology department heads that have to manage multiple system software packages can take advantage of a special tool called pterm. This is basically a dedicated X11 PuTTY client that runs on Unix machines like Apple's Macintosh platform as well as GNU/Linux PCs. Those who want to use it would first install PuTTY on a Windows PC and then get the pterm app up and running on one of their other machines. They can then connect the Windows PC to one of these other systems via a raw socket or over SSH.

Secured shell technology is generally preferred for this kind of application, but the app itself usually won't complain if you don't enable it while physically linking two machines together. Those who don't mind messing with a number of different socket configurations can even get PuTTY to pass raw packets over wireless networks. While this is more of an unsupported hack than it is an actual feature, it's popular enough that it gets some mention in the documentation.

Power users are going to be the ones who flock to PuTTY in the first place, so it makes sense that the software is packed with countless features that require a thick PDF manual to understand. Those who'd be interested in the software would likely not want it any other way.

Pros

  • Works with IPv6 connections
  • Runs as fast as the remote server sends packets
  • Supports running services over raw sockets
  • Emulates xterm control sequences
  • Can act like a VT102 or VT220 terminal if needed

Cons

  • No support for session tabs
  • Telnet connections are unsafe by design
  • Complicated command structure