RE: ssh-agent variables available to any user process

[Karl M]

Hi All...

From: Jörg Schaible Reply-To: To: "[ML] CygWin " Subject: RE: ssh-agent 
variables available to any user process
Date: Wed, 30 Aug 2006 08:02:46 +0200
Lapo Luchini wrote on Wednesday, August 30, 2006 12:42 AM:

> Under FreeBSD, I launch ssh-agent in my .xsession script and its
> environment is automatically inherited by every shell I then
> open in my
> X11 session.
> No such luck with Windows, but I found a way to propagate a
> environment variable to any (future) user process after the user is
> already logged.
> (or, at the very least...) Works for me.
>
> Variables will be then available on any shell and program opened after
> the attached script is executed.
> (put it in "Startup" menu in order to execute it at logon time)

I use a similar approach for years utilizing keychain. In my ~/.profile I 
have following lines:

I do domething similar, but skip using keychain because it adds so much time 
to launching a bash shell window. I just use ssh-agent directly. Once you do 
all this work, keychain isn't doing much for you.

====== %< =======
if test -z "`pidof ssh-agent`"; then
    keychain ~/.ssh/id_dsa
    . ~/.keychain/`hostname`-sh
    # Create batch files to be called from running shells
    cat ~/.keychain/`hostname`-sh | sed -e "s/;.*$//g" | u2d > 
~/.keychain/`hostname`-command.bat
    # Set environment directly
    regtool -s set /machine/SYSTEM/CurrentControlSet/Control/Session\ 
Manager/Environment/SSH_AUTH_SOCK $SSH_AUTH_SOCK
    regtool -s set /machine/SYSTEM/CurrentControlSet/Control/Session\ 
Manager/Environment/SSH_AGENT_PID $SSH_AGENT_PID
    # Broadcast of WM_SETTINGCHANGE
    update-env
else
    . ~/.keychain/`hostname`-sh
fi
====== %< =======

And update-env.c is:

====== %< =======
#include <windows.h>
int main() {
    SendMessage(HWND_BROADCAST, WM_SETTINGCHANGE, 0, 
(LPARAM)"Environment");
}
====== %< =======

build with Makefile:

====== %< =======
all: update-env.exe

%.exe: %.c
        gcc -mno-cygwin $^ -o $*
        strip $@
====== %< =======
I use

ssh-add -l >/dev/null 2>&1
if [ $? -eq 1 ]; then
 ssh-add
fi

in my profile and I launch ssh-agent from a service(one service for each 
user), so it survives logout on windows. The service and service installer 
bash scripts are attached.

I've considered supporting this as a package, but have not seen much 
interest.

I never found a way to broadcast the WM_SETTINGCHANGE directly form the 
script without the little helper app.
Neither did I. My helper application sendchenv.exe, but the same as 
update-env.exe. My source is also attached.

HTH,

...Karl

#!/bin/bash
# secret-agent-service-install service-name user-name

if [ "~$1" = "~" ]; then
 echo A service name is required.
 exit 1
fi

if [ "~$2" = "~" ]; then
 echo A user name is required.
 exit 1
fi

echo Uninstalling the secret-agent service, $1.
cygrunsrv --remove $1

echo Adding the \"Log on as a Service\" right for $2.
editrights -a SeServiceLogonRight -u $2

echo Installing the secret-agent service, $1.
cygrunsrv --install $1 \
 --args '/bin/secret-agent-service' \
 --disp "Secret Agent $2" \
 --desc "Creates an ssh-agent process for $2." \
 --path '/bin/bash' \
 --shutdown \
 --user "$2"

echo Starting the secret-agent service, $1.
cygrunsrv --start $1

#!/bin/bash
# Launch the ssh-agent from a service so it survives logoff.

# When the service stops, kill the ssh-agent.
trap "ssh-agent -k;
 exit 0" TERM

# Clean up old files that may be left behind after a crash.
#   The file permissions make this safe to do in a multi-user
#   environment, but "/tmp" must be local to this host.
rm -rf /tmp/ssh-*

# Launch the ssh-agent.
eval $(ssh-agent)

# Provide the ssh-agent socket ID via the registry and broadcast
#   the change in case the user is logged before we finish.
#   Do not provide the ssh-agent PID to minimize the risk of
#   killing the ssh-agent.
regtool -s set /HKEY_CURRENT_USER/Environment/SSH_AUTH_SOCK $SSH_AUTH_SOCK
sendchenv

# Wait quietly until the service is stopped.
while true; do
 sleep 24h &
 wait
done

// Notify all windows that environment variables may have changed.

#include <windows.h>

int main()
{
 DWORD dwReturnValue;

 if (SendMessageTimeout(HWND_BROADCAST, WM_SETTINGCHANGE, 0,
     (LPARAM) "Environment", SMTO_ABORTIFHUNG, 5000, &dwReturnValue))
   return 0;
 else
   return 1;
}


--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/