Thread: [ANNOUNCE] Keep Wi-Fi power-management off during SSH/SFTP sessions
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Bad_Habit is offline Bad_Habit
2011-11-30 , 21:04
Posts: 48 | Thanked: 32 times | Joined on Dec 2010 @ Russia, Moscow
#1
This is a dirty workaround, but no one seems to find a more elegant way.

Put these lines in your /etc/ssh/sshd_config
Code:
Compression no #optional
UseDNS no #optional
ForceCommand /usr/lib/openssh/ssh-session
Create /usr/lib/openssh/ssh-session
Code:
#!/bin/sh

if [ $USER = root ]; then
  IFCONFIG=ifconfig
  MGMT=/usr/lib/openssh/ssh-power-management
else
  IFCONFIG="sudo ifconfig"
  MGMT="sudo /usr/lib/openssh/ssh-power-management"
fi

WLAN_IP=$($IFCONFIG wlan0 | sed -n 's/.*inet addr:\([0-9.]\+\).*/\1/p')
SSH_IP=$(echo $SSH_CONNECTION | cut -d ' ' -f 3)

if [ "$WLAN_IP" = "$SSH_IP" ]; then
  ps -f | grep /usr/lib/openssh/ssh-power-management | grep -qv grep
  if [ $? -eq 1 ]; then
    $MGMT &
  fi
fi

if [ -n "$SSH_ORIGINAL_COMMAND" ]; then
  eval $SSH_ORIGINAL_COMMAND
else
  $SHELL
fi
Create /usr/lib/openssh/ssh-power-management
Code:
#!/bin/sh

if [ $USER = root ]; then
  IWCONFIG="iwconfig"
else
  IWCONFIG="sudo iwconfig"
fi

while [ $(lsof -a -i4 -a -i :ssh | grep ESTABLISHED | wc -l) -gt 0 ]; do
  $IWCONFIG wlan0 power off
  $IWCONFIG wlan0 txpower 100mW
  sleep 20
done

$IWCONFIG wlan0 power on
$IWCONFIG wlan0 txpower 10mW
You need to have wireless-tools installed (and sudser if you don't want to add an appropriate entry to /etc/sudoers.d/).

Then run
Code:
sudo chmod +x /usr/lib/openssh/ssh-session
sudo chmod +x /usr/lib/openssh/ssh-power-management
sudo /etc/init.d/ssh restart
Authentication process will remain slow and you'll notice a small gap after login; then the lags will disappear until you close all active ssh/sftp connections.
The 20 seconds timeout for invoking iwconfig isn't meant to be precise, test and report your measures.

---------------------------

If you use ssh server only at home, you may also want to do this:

Create /etc/network/if-up.d/ssh (replace YOUR_AP_ESSID with the name of your access point)
Code:
#!/bin/sh

if [ "$ICD_CONNECTION_TYPE" = "WLAN_INFRA" ] ; then
        KEY="/system/osso/connectivity/IAP/$ICD_CONNECTION_ID/name"
        AP=$(/usr/bin/gconftool -g "$KEY")
        if [ "$AP" = "YOUR_AP_ESSID" ] ; then
                /etc/init.d/ssh start
        fi
fi

exit 0
and /etc/network/if-down.d/ssh
Code:
#!/bin/sh

/etc/init.d/ssh stop

exit 0
Comment out the corresponding lines in /etc/event.d/sshd
Code:
#start on stopped rcS

console output

#respawn

pre-start script
    if [ ! -d /var/run/sshd ] ; then
        mkdir /var/run/sshd
        chmod 755 /var/run/sshd
    fi
end script

exec /usr/sbin/sshd -D
Then run
Code:
sudo chmod +x /etc/network/if-*.d/ssh
sudo update-rc.d -f ssh remove
Last edited by Bad_Habit; 2011-12-06 at 13:26.
 

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