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cyberskydive

Telnet or SSH?

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Telnet is bad. If I run a sniffer on your network, or any pc/router between you and your destination, I can read everything you type in telnet, including passwords.
ssh is encrypted, so a sniffer does me no good. It's tough to break, and even has some little precautions to stop "man in the middle" attacks.
Telnet has no support for transferring files. You need ftp for that. ftp is not secure, either.
scp on the other hand, uses an encrypted channel, so you can securely copy files across the net.
I believe that ssh has some additional features not available in telnet, not the other way around.

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SSH uses encryption on the data stream so your session can't be snooped. It also checks keys between hosts and will warn you if the target machine has been switched.
The best feature of SSH though is that it'll encapsulate your X windows protocol stream.
Not a big deal if you're on windows, but going Unix to Unix it means I can run remote graphical applications locally even through a firewall.

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What they said. In addition to tunelling X Windows, you can set up tunnels for any other listening port (on either side, any machine that either side can see). I use this to access servers at work from home though the NAT/firewall.
As far as clients go, puTTY is OK, but I like TeraTerm with the ssh mods better. My favorite, tho, is OpenSSH. There is a nice Windows port of it available as part of the most excellent Cygwin package. If you are a Unix person stuck in a Windows world, you owe it to yourself to install these tools. It contains basically all of the GNU stuff and more, ported to Winblows.
Carl

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cyberskydive> yeah- this is the UNIX support forums
And I was thinking I was the only nerd here :-)
The main difference between SSH and telnet is security.
SSH sessions are encrypted. This means that if somebody is snooping
your session (something that every annoying moron with your average
script-kiddie hacking kit can do), he/she/it won't be able to make any
sense of it. If you use plain telnet, everything goes over in the open.
This includes usernames, passwords and other sensitive information.
So, snoopers will be able to intercept your username and password and
abuse it as they see fit.
I'm not sure if SSH has eavesdropping protection or not.
For copying files, use scp or sftp. These are encrypted versions of rcp
and ftp respectively.
Mind you, though, that telnet isn't all bad.
Many servers run daemons that you can communicate with, simply by
setting up a socket connection to a specific port. Instead of writing a C
program to do that, you can simply use telnet to connect to that port.
The problem with SSH in this case is that in order for SSH to work, both
parties must be able to handle the encryption. For some services like
remote login, encryption makes a lot of sense because sensitive
information (e.g. passwords) is involved. But there are a lot of services
out there that don't support encryption.
For example: I have no direct login access to the machine that acts as
our news server. But I can (legitimately!) use telnet to connect to that
machine on the usenet port. Then, I can query the machine e.g. about
which newsgroups it feeds. I have to use telnet for this, because the
news server isn't capable of encrypting the session. But since I'm not
requesting or supplying any sensitive information, this is not a problem.
Another example: by telnetting to the mail port of the mailserver, I can
send and read e-mail without an e-mail client (e.g. mutt or elm). All I need
is telnet. However, I never do this because the mailserver requires
authentication (username and password) but doesn't support encryption.
Wow, this message is getting way too long.
Blue skies and sorry to bore you,
Alphons

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Quote

by telnetting to the mail port of the mailserver, I can
send and read e-mail without an e-mail client.


Do you also surf the web by telnetting to port 80?
But you're right. Telnet has its uses when it comes to troubleshooting.

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