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2.4.1 Connecting with rsh and ssh

CVS uses the remote shell protocol to perform operations on the server, via the ‘rsh’ or ‘ssh’ commands. The protocol used by ‘ssh’ provides secure authentication and encryption, while the ‘rsh’ command has minimal security and is only suitable for a closed environment.⁽¹⁾ Whatever remote shell command is used, the remote user host needs to have a working login configuration, such as a ‘.rhosts’ or ‘~/.ssh/authorized_keys’ file which grants access to the local user.

For example, suppose you are the user ‘mozart’ on the local machine ‘toe.example.com’, and the server machine is ‘faun’. If you want to connect by ‘rsh’, put the following line into the file ‘.rhosts’ in ‘bach’'s home directory on faun:

toe.example.com  mozart

Then test that ‘rsh’ is working with

$ rsh -l bach faun 'echo $PATH'

To connect by ‘ssh’, first set up your login credentials (for example, by generating a public key with ssh-keygen and copying it to the ‘~/.ssh/authorized_keys’ file on the remote host). Then check that the connection is working with

$ ssh -l bach faun 'echo $PATH'

and set the environment variable CVS_RSH to ssh as follows:

$ CVS_RSH=ssh
$ export CVS_RSH

Next you have to make sure that rsh or ssh will be able to find the CVS server executable. Make sure that the path which was printed in the above example includes the directory containing a program named cvs which is the server. You need to set the path on the remote server in ‘.bashrc’, ‘.cshrc’, etc., not ‘.login’ or ‘.profile’. Alternately, you can set the environment variable CVS_SERVER on the client machine to the filename of the server you want to use, for example ‘/usr/local/bin/cvs-1.6’.

There is no need to edit ‘inetd.conf’ or start a CVS server daemon.

There are two access methods that you use in CVSROOT. :server: specifies an internal rsh client, which is supported only by some CVS ports. :ext: specifies an external rsh program. By default this is rsh but you may set the CVS_RSH environment variable to invoke another program which can access the remote server, such as ssh as shown above.⁽²⁾ It must be a program which can transmit data to and from the server without modifying it; for example the Windows NT rsh is not suitable since it by default translates between CRLF and LF.⁽³⁾

Continuing our example, supposing you want to access the module ‘foo’ in the repository ‘/usr/local/cvsroot/’, on machine ‘faun’, you are ready to go:

$ cvs -d :ext:bach@faun:/usr/local/cvsroot checkout foo

(The ‘bach@’ can be omitted if the username is the same on both the local and remote hosts.)

2.4.2 Other access methods

In addition to using remote shell commands, there are several ways clients can access a CVS server directly over a TCP connection. These are described in section 17 The CVS server.