Using CVS (with Linux)

$Revision: 1.1 $
$Date: 2002/02/22 19:49:08 $

Prepared by Rick Hall, 2/22/2002

This is a brief note describing my experiences so far using CVS, SSH and SourceForge under Linux. It is a work in progress, since there are a few things that I don't have quite right yet.

Until recently, I've been using CVS on SourceForge in 'password' mode. Each time I type a command, CVS asks for my password. This works, but it is tedious.

About a week ago, I spent some time getting RSA keys to work. Now CVS does not ask for my password, but rather exchanges RSA keys with SSH.

I don't have everything completely working (there's a bit of a kludge getting ssh-agent to run), but I find CVS much more usable. So here is what I did, in case you'd like to try it (or point out how to improve it!).

Procedure:

  1. The SourceForge documentation is a bit ambiguous about whether SSH1 or SSH2 or both will work with CVS. At one point, the docs state categorically that SSH1 is required; elsewhere the docs imply SSH2 is OK. I decided to play it safe and use SSH1.

    2. However, the first problem is that 'ssh1' is not a valid command on my machine. To invoke SSH1, the correct command is 'ssh -1'. However, the SourceForge docs imply that exporting "CVS_RSH='ssh -1'" will not work. I tried creating an ssh1 alais in my /etc/bashrc config file, but that didn't work either. In the end, I took the brute force approach. I created a file /usr/bin/ssh1 that contained a short script: 

    
  #!/bin/bash
  /usr/bin/ssh -1 $@
    and changed permissions on this file to "a+x". I verified that I could log into SourceForge using this newly minted 'ssh1' command. 
    
  export CVS_RSH=ssh1
  cvs -z3 -d:ext:rphall@cvs.clra.sourceforge.net:/cvsroot/clra history
  2. Per SourceForge documentation (Go to your Account Maintainance page, click on the Edit Keys link and follow the instructions) I created SSH1-compatible RSA keys.

    3. From a command line on my (local) computer: 

    
  ssh-keygen -t rsa1 -f ./.ssh/identity
    This created an RSA key in ~/.ssh/identity and a public key in ~/.ssh/identity.pub.

  3. I cut and pasted the contents of my public key into the SourceForge form on the "Edit Keys" page.

    4. The contents were on a single line, but contained embedded spaces. Here's what it looked like, since my public key is, well, public (the qutation marks are delimiters and not part of the key contents): 

    
  "1024 35 13899619466844501320359800988063331471833014905
   0406128654592710211670078564967537728373381022392226681
   3081299731058791031225357896138980186060356329398558491
   6501714023546654312634718113907900315542309686691092850
   5717386951573651602893147115376708782549824408891378313
   544466376870749497023213960269834986082579
   rphall@devserver.dev.penaccess.com"
    After about 15 minutes (much shorter than the 6 hours advertised by SourceForge), my new key was active.

  4. I started 'ssh-agent'

    5. 
  ssh-agent
    This program should be started when an X session starts, but I haven't figured out how to do this. As a workaround, when ssh-agent starts from a command line, it prints some handy environment variables. I exported these to my environment: 
    
  SSH_AUTH_SOCK=/tmp/ssh-XXDfJN8t/agent.17866; export SSH_AUTH_SOCK;
  SSH_AGENT_PID=17867; export SSH_AGENT_PID;

  5. I added my RSA keys to the running ssh-agent

    6. 
  ssh-add

  6. After this last step, I was able to use CVS on SourceForge (from any terminal in which the ssh-agent environment variables were exported) without typing my SSH password.