Programming – Page 5 – Ryan Schulze

Controlling SSH identities

September 30, 2010May 13, 2013Ryan1 Comment

SSH has a few strange undocumented “features”. One of which is the way it handles identities via agent and command line. It is possible to specify an identity file to use for ssh via the -i parameter (ssh -i identity_file $host). What the manpage doesn’t mention, is that the specified identity isn’t forced for the connection, it is just added to the list of possible identities.
To make matters worse, ssh tries the identities from the agent first. So if agent forwarding is enabled and valid for the destination the ssh command will never use the identity specified with -i. Why is this “bad”? Because the identity specified may be used for specific tasks with commands linked to them on the destination (e.g. automatic restarts, backups, …)

Sooo, as a solution I whipped up the following function as a workaround in my scripts, I add a function called “xssh”:

xssh() { #{{{
local identity="/root/.ssh/special_identity"
ssh-add -l &gt;/dev/null \
&amp;&amp; ssh -a ${USER}@localhost "ssh -o connecttimeout=10 -o stricthostkeychecking=no -i $identity ${@}" \
|| ssh -o connecttimeout=10 -o stricthostkeychecking=no -i $identity ${@}
} #}}}

xssh() { #{{{

local identity="/root/.ssh/special_identity"

ssh-add -l >/dev/null \

&& ssh -a ${USER}@localhost "ssh -o connecttimeout=10 -o stricthostkeychecking=no -i $identity ${@}" \

|| ssh -o connecttimeout=10 -o stricthostkeychecking=no -i $identity ${@}

} #}}}

I know it looks ugly, if it finds a key in the agent it makes a ssh connection to the current host with agent forwarding deactivated and then executes the ssh parameters passed. If no key is found in the ssh agent it does everything as normal.

Script of the day – clean up stale .ssh/known_hosts

August 19, 2010May 13, 2013Ryanbash

This little script takes an IP or hostname as a parameter, and if there is an offending key in the .ssh/known_hosts it removes it and replaces it with the current valid one useful if you are moving/reinstalling a large amount of servers …

#!/bin/bash
#===============================================================================
# FILE: ssh-cleankey.sh
# USAGE: ./ssh-cleankey.sh 
#
# DESCRIPTION: deletes stale ssh known_hosts entries
#===============================================================================

# true or fasle
VERBOSE=false

#=== Exit codes ================================================================
# 1 - Not a valid IP or not reachable
#===============================================================================

#=== FUNCTION ================================================================
# NAME: print_help
# DESCRIPTION: Prints help and exits
#===============================================================================
print_help() { #{{{
echo "Usage: `basename $0` "
echo ""
echo "e.g. ./`basename $0` 1.2.3.4"
echo ""
exit 0
} #}}}

if [[ $# -eq 1 ]]
then
HOST="${1}"
else
print_help
fi

ping -w1 -c1 $HOST &gt;/dev/null 2&gt;&amp;1
if [[ $? != 0 ]]
then
$VERBOSE &amp;&amp; echo "ERROR: $HOST is either not a valid IP/hostname, or is not reachable via ping"
exit 1
fi

Check=$(ssh -o connecttimeout=10 -o stricthostkeychecking=no $HOST true 2&gt;&amp;1|grep -c "Offending key")
if [[ $Check -gt 0 ]]
then
$VERBOSE &amp;&amp; echo "$HOST is stale, updating known_hosts"
ssh-keygen -R $HOST &gt;/dev/null 2&gt;&amp;1
ssh -o connecttimeout=10 -o stricthostkeychecking=no $HOST true &gt;/dev/null 2&gt;&amp;1
else
$VERBOSE &amp;&amp; echo "$HOST is OK"
fi

exit 0

#!/bin/bash

#===============================================================================

# FILE: ssh-cleankey.sh

# USAGE: ./ssh-cleankey.sh

# DESCRIPTION: deletes stale ssh known_hosts entries

#===============================================================================

# true or fasle

VERBOSE=false

#=== Exit codes ================================================================

# 1 - Not a valid IP or not reachable

#===============================================================================

#=== FUNCTION ================================================================

# NAME: print_help

# DESCRIPTION: Prints help and exits

#===============================================================================

print_help() { #{{{

echo "Usage: `basename $0` "

echo ""

echo "e.g. ./`basename $0` 1.2.3.4"

echo ""

exit 0

} #}}}

if [[ $# -eq 1 ]]

then

HOST="${1}"

else

print_help

ping -w1 -c1 $HOST >/dev/null 2>&1

if [[ $? != 0 ]]

then

$VERBOSE && echo "ERROR: $HOST is either not a valid IP/hostname, or is not reachable via ping"

exit 1

Check=$(ssh -o connecttimeout=10 -o stricthostkeychecking=no $HOST true 2>&1|grep -c "Offending key")

if [[ $Check -gt 0 ]]

then

$VERBOSE && echo "$HOST is stale, updating known_hosts"

ssh-keygen -R $HOST >/dev/null 2>&1

ssh -o connecttimeout=10 -o stricthostkeychecking=no $HOST true >/dev/null 2>&1

else

$VERBOSE && echo "$HOST is OK"

exit 0

bash: using the content of a variable as variable name

August 5, 2010March 12, 2011Ryanbash

Since the implementation of Arrays in Bash is somewhat lacking compared to higher level programming languages (only one-dimensional), and hash lists require a bit of work to set up, you may run into a situation where you have a small list of key/value pairs that are both variable and you need to store.
There are various solutions for the problem, e.g. creating two arrays (one for the keys, one for the values, and combining them by using the same index values for the entries), or using the functions from the link above to build a hash list. For me the easiest way to solve the problem, if I only have a few variables and don’t want to bloat the code, is to (mis)use declare. declare is intended for setting the type of a variable (constant, array, integer,…), but has the nice side affect that you can use variables in the key name, and you can set the value of the variable.

usage:
declare ${Key}=${Value}

Example:
$File_Config is variable holding the name of a configfile, the content of the file could look like this:
foo:one bar:three foobar:bignumber

Snippet:

if [[ -e "${File_Config}" ]]
then
while read line
do
Key="${line%%:*}" # chop off everything after the first :
Value="${line#*:}" # chop off everything before the first :
Value="$(echo ${Value}|sed 's#^ +##g;s# +$##g')" # chop off any excess whitespace
if [[ "${Key}" != "" &amp;&amp; "${Value}" != "" ]] # only continue if we have something to do
then
declare Configuration_${Key}="${Value}"
fi
done &lt; "${File_Config}"
fi

if [[ -e "${File_Config}" ]]

then

while read line

Key="${line%%:*}" # chop off everything after the first :

Value="${line#*:}" # chop off everything before the first :

Value="$(echo ${Value}|sed 's#^ +##g;s# +$##g')" # chop off any excess whitespace

if [[ "${Key}" != "" && "${Value}" != "" ]] # only continue if we have something to do

then

declare Configuration_${Key}="${Value}"

done < "${File_Config}"

after the snippet has read the configfile, you can use $Configuration_foo, $Configuration_bar and $Configuration_foobar in your script. The keynames could also have came from a mysql query, array, command line args, …

Grid clicker script

April 26, 2010May 13, 2013RyanAutohotkey, Farmville, funfari

I finished up my “grid clicker” script. it is intended to simplify testing of games where you have to click certain patterns (a grid). Typical facebook games like farmville or funfari are great examples of this. just download the file (here is the sourcecode), execute it, and an eye should appear in your task bar. Double clicking on the icon in your task bar will start the script, just follow the instructions and everything should be fine.

And while I am at it: here is a spreadsheet I started for plants/trees/animals in funfari: Google online spreadsheets

Farmville

November 25, 2009September 27, 2014Ryan1 CommentAutohotkey, Farmville, Script

Farmvill can be a fun way to pass some time, but if your fields get to be a bit big clicking on every single field can get to be a bit tiresome. I found this autohotkey script in the depths of the internet. It simplifies the process greatly 😉

!^c::
GoSub GetFarmSq
GoSub Getfirstsq

i=1

SetMouseDelay, 0

cycle := farmy/2
newx=%startx%
newy=%starty%
loop, %cycle%
{
Click %newx%,%newy%
Loop, %farmx%
{
newx+=25
newy-=12
Click %newx%,%newy%
}
newx+=25
newy+=12
Click %newx%,%newy%
Loop, %farmx%
{
newx-=25
newy+=12
Click %newx%,%newy%
}
newx+=25
newy+=12
}

return

GoSub Getfirstsq

GetFarmsq:
Inputbox, farmy, Hi, Enter the number of fields to the right to click on,,200,150,,,,,6
if ErrorLevel
GoSub Esc
Inputbox, farmx, Hi, Enter the number of fields upwards to click on,,200,150,,,,,6
if ErrorLevel
GoSub Esc
farmx--
return

Getfirstsq:
Msgbox, Click on the leftmost field to start with ("9 O'clock" position).
KeyWait, LButton, D
KeyWait, LButton, D
MouseGetPos, startx, starty
return

Esc:
!^x::reload
Return

!^c::

GoSub GetFarmSq

GoSub Getfirstsq

i=1

SetMouseDelay, 0

cycle := farmy/2

newx=%startx%

newy=%starty%

loop, %cycle%

{

Click %newx%,%newy%

Loop, %farmx%

{

newx+=25

newy-=12

Click %newx%,%newy%

}

newx+=25

newy+=12

Click %newx%,%newy%

Loop, %farmx%

{

newx-=25

newy+=12

Click %newx%,%newy%

}

newx+=25

newy+=12

}

return

GoSub Getfirstsq

GetFarmsq:

Inputbox, farmy, Hi, Enter the number of fields to the right to click on,,200,150,,,,,6

if ErrorLevel

GoSub Esc

Inputbox, farmx, Hi, Enter the number of fields upwards to click on,,200,150,,,,,6

if ErrorLevel

GoSub Esc

farmx--

return

Getfirstsq:

Msgbox, Click on the leftmost field to start with ("9 O'clock" position).

KeyWait, LButton, D

MouseGetPos, startx, starty

return

Esc:

!^x::reload

Return