forwarding SSH-Authentication

[Thomas Heine]

Hello erverybody.

I read the man-Pages but i didn't find a solution, maybe you can help
me.

I've got to connect to two different machines from on
administration server. For convenience both machines should be
accessible
with the same private key.

Now my Problem: I want to tunnel the ssh connection from adminstration 
server to host2 via host1.
The Problem, i dont't want to install the private key on host 1

Is it possible to forward the authentication? 

Regrads 
Thomas 
-- 
Thomas Heine