ssh-agent variables available to any user process

ssh-agent variables available to any user process

[Lapo Luchini]

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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)

-- 
Lapo Luchini
lapo@lapo.it (OpenPGP & X.509)
www.lapo.it (Jabber, ICQ, MSN)

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RE: ssh-agent variables available to any user process

[Karl M]

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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


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#!/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


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#!/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


[-- Attachment #4: sendchenv.c --]
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// 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;
}



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RE: ssh-agent variables available to any user process

[Jörg Schaible]

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:

====== %< =======
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 never found a way to broadcast the WM_SETTINGCHANGE directly form the script without the little helper app.

- Jörg

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