\versionid $Id: plink.but,v 1.15 2002/03/05 20:39:27 simon Exp $ \C{plink} Using the command-line connection tool Plink \i{Plink} (PuTTY Link) is a command-line connection tool similar to UNIX \c{ssh}. It is mostly used for automated operations, such as making CVS access a repository on a remote server. Plink is probably not what you want if you want to run an interactive session in a console window. \H{plink-starting} Starting Plink Plink is a command line application. This means that you cannot just double-click on its icon to run it and instead you have to bring up a \i{console window}. In Windows 95, 98, and ME, this is called an \q{MS-DOS Prompt}, and in Windows NT and 2000 it is called a \q{Command Prompt}. It should be available from the Programs section of your Start Menu. In order to use Plink, the file \c{plink.exe} will need either to be on your \i{\c{PATH}} or in your current directory. To add the directory containing Plink to your \c{PATH} environment variable, type into the console window: \c set PATH=C:\path\to\putty\directory;%PATH% This will only work for the lifetime of that particular console window. To set your \c{PATH} more permanently on Windows NT, use the Environment tab of the System Control Panel. On Windows 95, 98, and ME, you will need to edit your \c{AUTOEXEC.BAT} to include a \c{set} command like the one above. \H{plink-usage} Using Plink This section describes the basics of how to use Plink for interactive logins and for automated processes. Once you've got a console window to type into, you can just type \c{plink} on its own to bring up a usage message. This tells you the version of Plink you're using, and gives you a brief summary of how to use Plink: \c Z:\sysosd>plink \c PuTTY Link: command-line connection utility \c Release 0.50 \c Usage: plink [options] [user@]host [command] \c Options: \c -v show verbose messages \c -ssh force use of ssh protocol \c -P port connect to specified port \c -pw passw login with specified password Once this works, you are ready to use Plink. \S{plink-usage-interactive} Using Plink for interactive logins To make a simple interactive connection to a remote server, just type \c{plink} and then the host name: \c Z:\sysosd>plink login.example.com \c \c Debian GNU/Linux 2.2 flunky.example.com \c flunky login: You should then be able to log in as normal and run a session. The output sent by the server will be written straight to your command prompt window, which will most likely not interpret terminal control codes in the way the server expects it to. So if you run any full-screen applications, for example, you can expect to see strange characters appearing in your window. Interactive connections like this are not the main point of Plink. In order to connect with a different protocol, you can give the command line options \c{-ssh}, \c{-telnet}, \c{-rlogin} or \c{-raw}. To make an SSH connection, for example: \c Z:\sysosd>plink -ssh login.example.com \c login as: If you have already set up a PuTTY saved session, then instead of supplying a host name, you can give the saved session name. This allows you to use public-key authentication, specify a user name, and use most of the other features of PuTTY: \c Z:\sysosd>plink my-ssh-session \c Sent username "fred" \c Authenticating with public key "fred@winbox" \c Last login: Thu Dec 6 19:25:33 2001 from :0.0 \c fred@flunky:~$ \S{plink-usage-batch} Using Plink for automated connections More typically Plink is used with the SSH protocol, to enable you to talk directly to a program running on the server. To do this you have to ensure Plink is \e{using} the SSH protocol. You can do this in several ways: \b Use the \c{-ssh} option as described in \k{plink-usage-interactive}. \b Set up a PuTTY saved session that describes the server you are connecting to, and that also specifies the protocol as SSH. \b Set the Windows environment variable \c{PLINK_PROTOCOL} to the word \c{ssh}. Usually Plink is not invoked directly by a user, but run automatically by another process. Therefore you typically do not want Plink to prompt you for a user name or a password. To avoid being prompted for a user name, you can: \b Use the \c{-l} option to specify a user name on the command line. For example, \c{plink login.example.com -l fred}. \b Set up a PuTTY saved session that describes the server you are connecting to, and that also specifies the username to log in as (see \k{config-username}). To avoid being prompted for a password, you should almost certainly set up public-key authentication. (See \k{pubkey} for a general introduction to public-key authentication.) Again, you can do this in two ways: \b Set up a PuTTY saved session that describes the server you are connecting to, and that also specifies a private key file (see \k{config-ssh-privkey}). For this to work without prompting, your private key will need to have no passphrase. \b Store the private key in Pageant. See \k{pageant} for further information. Once you have done all this, you should be able to run a remote command on the SSH server machine and have it execute automatically with no prompting: \c Z:\sysosd>plink login.example.com -l fred echo hello, world \c hello, world \c \c Z:\sysosd> Or, if you have set up a saved session with all the connection details: \c Z:\sysosd>plink mysession echo hello, world \c hello, world \c \c Z:\sysosd> Then you can set up other programs to run this Plink command and talk to it as if it were a process on the server machine. You may also find it useful to use the \c{-batch} command-line option; see \k{plink-usage-options-batch}. \S{plink-usage-options} Options This section describes the command line options that Plink accepts. \S2{plink-usage-options-v}\c{-v} show verbose messages By default, Plink only displays any password prompts and the output of the remote command. The \c{-v} option makes it print extra information about the connection being made, for example: \c Server version: SSH-1.5-OpenSSH-1.2.3 \c We claim version: SSH-1.5-PuTTY \c Using SSH protocol version 1 \c Received public keys \c Host key fingerprint is: \c 1023 e3:65:44:44:bd:b1:04:59:bc:e2:3d:a1:4d:09:ce:99 \c Encrypted session key \c Using 3DES encryption \c Trying to enable encryption... \c Successfully started encryption \c Sent username "fred". \c Sent username "fred" \c fred@example.com's password: This information can be useful for diagnosing problems. \S2{plink-usage-options-ssh} Protocol selection options Plink is most useful when using the SSH protocol. However, it allows you to interface to all the protocols supported by PuTTY. You can specify the option \c{-ssh} on the command line to select the SSH protocol; you can also specify \c{-telnet}, \c{-rlogin} or \c{-raw} to select other protocols. \S2{plink-usage-options-P}\c{-P port} connect to specified port If your server machine is running its SSH service on a port other than the standard one, you can specify an alternative port number to connect to using the \c{-P} option, like this: \c plink -ssh login.example.com -P 5022 \S2{plink-usage-options-pw}\c{-pw passw} login with specified password A simple way to automate a remote login is to supply your password on the Plink command line. This is \e{not recommended} for reasons of security. If you possibly can, we recommend you set up public-key authentication instead. See \k{pubkey} for details. Note that the \c{-pw} option only works when you are using the SSH protocol. Due to fundamental limitations of Telnet and Rlogin, these protocols do not support automated password authentication. \S2{plink-usage-options-user}\c{-l username} login with specified username As described in \k{plink-usage-batch}, you can specify the user name to log in as on the remote server using the \c{-l} option. For example, \c{plink login.example.com -l fred}. \S2{plink-usage-options-batch}\c{-batch} avoid interactive prompts If you use the \c{-batch} option, Plink will never give an interactive prompt while establishing the connection. If the server's host key is invalid, for example (see \k{gs-hostkey}), then the connection will simply be abandoned instead of asking you what to do next. This may help Plink's behaviour when it is used in automated scripts: using \c{-batch}, if something goes wrong at connection time, the batch job will fail rather than hang. \S2{plink-usage-options-cmdfile} \c{-m filename} read command from a file If the command you want to run on the remote server is particularly large, you can read it from a file using the \c{-m} option, instead of putting it directly on Plink's command line. On most Unix systems, you can even put multiple lines in this file and execute more than one command in sequence, or a whole shell script. \S2{plink-usage-options-portfwd} \c{-L} and \c{-R} set up port forwarding Plink allows you to use port forwarding just as PuTTY does; if you have set up a PuTTY saved session that specifies port forwardings, and you connect to that session using Plink, then the same port forwardings will be set up. For convenience, Plink also offers the option to set up port forwarding on the command line. The command-line options work just like the ones in Unix \c{ssh} programs. To forward a local port (say 5110) to a remote destination (say \cw{popserver.example.com} port 110), you can write: \c plink mysession -L 5110:popserver.example.com:110 And to forward a remote port to a local destination, just use the \c{-R} option instead of \c{-L}: \c plink mysession -R 5023:mytelnetserver.myhouse.org:23 For general information on port forwarding, see \k{using-port-forwarding}. \H{plink-batch} Using Plink in \i{batch files} and \i{scripts} Once you have set up Plink to be able to log in to a remote server without any interactive prompting (see \k{plink-usage-batch}), you can use it for lots of scripting and batch purposes. For example, to start a backup on a remote machine, you might use a command like: \c plink root@myserver /etc/backups/do-backup.sh Or perhaps you want to fetch all system log lines relating to a particular web area: \c plink mysession grep /~fjbloggs/ /var/log/httpd/access.log > fredlogs Any non-interactive command you could usefully run on the server command line, you can run in a batch file using Plink in this way. \H{plink-cvs} Using Plink with \i{CVS} To use Plink with CVS, you need to set the environment variable \c{CVS_RSH} to point to Plink: \c set CVS_RSH=\path\to\plink.exe You also need to arrange to be able to connect to a remote host without any interactive prompts, as described in \k{plink-usage-batch}. You should then be able to run CVS as follows: \c cvs -d :ext:user@sessionname:/path/to/repository co module If you specified a username in your saved session, you don't even need to specify the \q{user} part of this, and you can just say: \c cvs -d :ext:sessionname:/path/to/repository co module \H{plink-wincvs} Using Plink with \i{WinCVS} Plink can also be used with WinCVS. Firstly, arrange for Plink to be able to connect to a remote host non-interactively, as described in \k{plink-usage-batch}. Then, in WinCVS, bring up the \q{Preferences} dialogue box from the \e{Admin} menu, and switch to the \q{Ports} tab. Tick the box there labelled \q{Check for an alternate \cw{rsh} name} and in the text entry field to the right enter the full path to \c{plink.exe}. Select \q{OK} on the \q{Preferences} dialogue box. Next, select \q{Command Line} from the WinCVS \q{Admin} menu, and type a CVS command as in \k{plink-cvs}, for example: \c cvs -d :ext:user@hostname:/path/to/repository co module or (if you're using a saved session): \c cvs -d :ext:user@sessionname:/path/to/repository co module Select the folder you want to check out to with the \q{Change Folder} button, and click \q{OK} to check out your module. Once you've got modules checked out, WinCVS will happily invoke plink from the GUI for CVS operations. \# \H{plink-whatelse} Using Plink with... ?