Starting with Windows 7 and Eclipse Indigo you need to start Eclipse as administrator to be able to install plugins.
This is true as well for plugins which do not have an install site. Those plugins must be placed in the dropins folder of your eclipse install.
If in Eclipse, using ant scp you get the error:
Cause: Could not load a dependent class com/jcraft/jsch/Logger
It is not enough to have Ant's optional JARs
you need the JAR files that the optional tasks depend upon.
Ant's optional task dependencies are listed in the manual.
Action: Determine what extra JAR files are needed, and place them in one of:
-C:\Program Files (x86)\Eclipse\plugins\org.apache.ant_1.8.2.v20110505-1300\lib
-C:\Users\pbu.DESKTOP-KSA\.ant\lib
-a directory added on the command line with the -lib argument
Do not panic, this is a common problem.
The commonest cause is a missing JAR.
This is not a bug; it is a configuration problem
You need to do 3 things:
jsch.jar from http://www.jcraft.com/jsch/