Connecting to our server using SSH and copying files using SFTP

The TELNET and FTP protocols do not support encryption. That means that all transferred data, including usernames and passwords, are transferred as plain texts. Therefore, these protocols are considered insecure. Anyone using a packet sniffer between the FTP- or TELNET client and the server can easily pick usernames and passwords, potentially abusing them. This way the personal files of the victim user may be accessed. Since the system is more vulnerable to internal attacks, by gaining privileges, they can gain access to anyone's files and they can even destroy them. In the past years we have have discovered several such unauthorized access to the user accounts.

To avoid this problem, we have decided not to support TELNET and FTP on our system. SSH is the successor of TELNET and SFTP is the successor of FTP. Using these programs one can connect or transfer files via a secure line. These programs are available for many years now, and are well known by most of our users. These programs are usually part of the different Linux distributions. For Windows systems they can be downloaded from here: https://www.putty.org/

We kindly ask anyone wishing to connect to our server or transfer files from/to our server to install and use the SSH and SFTP programs using the guidelines above. The telnet and real user ftp clients can connect to our server renyi.hu only from the internal network of the Institute, and the server ftp://ftp.hexagon.renyi.hu will serve only anonymous requests. From outside of the Institute's network you can connect to our server hexagon.renyi.hu only by using the above mentioned SSH or SFTP clients.

You'll find OS specific help here:

• For Linux:

Please use the Institute's Linux system. The following programs are available: ssh - the traditional command line ssh client program. Usage: ssh username@hexagon.renyi.hu -p port_number The port number is sent to every user in the first email after the account is created.

ATTENTION: On 2022. 10. 21., the Hexagon and Hexagon2 servers are being upgraded; if you have used the servers before (and saved the SSH key), you must issue the following command in case of unsuccessful login attempt:

ssh-keygen -R "hexagon"
ssh-keygen -R "[hexagon]:2820"
ssh-keygen -R "[hexagon.renyi.hu]:2820"
ssh-keygen -R "[193.224.79.14]:2820"

or

ssh-keygen -R "hexagon2"
ssh-keygen -R "[hexagon2]:2820"
ssh-keygen -R "[hexagon2.renyi.hu]:2820"

Konqueror - Konqueror is a web browser/file browser, which is a part of the KDE Desktop Environment. Newer versions of Konqueror supports SFTP (Secure FTP).

SFTP - sftp is a command line program, which is a part of the OpenSSH package. sftp works almost like regular command line ftp in dos and unix.

Settings, usage: Konqueror

SFTP

• For Windows:

The following programs are available: WinSCP - Free SFTP and FTP client for Windows.

PuTTY - A free telnet/ssh client.

SSH Secure Shell Client 3.2.9 is a commercial client from SSH Communications Security. The client is free for evaluation, non-commercial and university use.

Settings, usage: WinSCP Installer: all the parameters are good, which the installer offers. Use: hostname: hexagon.renyi.hu username: Institutional username password: Institutional password And the port should be set correctly (in the middle of July 2012, we sent the number via email to all hosts.) The port number is also indicated on the account request form, or you can inquire by e-mail to the system. Stay in the default protocol then press the login button. If you are asked if you want to remember the key permanently, then you have to say Yes. This question is asked only when the first connection is made. You will see two windows, the local machine on the left, the Rényi server on the right.

PUTTY Installer: The default setting parameters are correct. Usage: host: hexagon.renyi.hu protocol: SSH If you are asked if you want to remember the key permanently, then you have to say Yes. This question is asked only when the first connection is made.

SSHWin - This client is pretty easy to use. Just start the SSH Secure File Transfer Client-program. Press the Quick Connect button. The server name should be renyi.hu and and the port should be set correctly (in the middle of July 2012, we sent the number via email to all hosts.) The port number is also indicated on the account request form, or you can inquire by e-mail to the system. Then press Connect. If this is the first time you connect to a server, you will be asked to add the server. Just answer Yes. Next you will be asked to provide a password. You will see the files from your home directory on the server in the right frame and local files in the left frame. Just drag'n'drop files to/from the server/your local machine.

ATTENTION: On 2022. 10. 21., the Hexagon and Hexagon2 servers are being upgraded; if you have used the servers before (and saved the SSH key), you have to approve the pop-up warning about the change of keys.