how to allow putty to ssh a remote site server using proxy

[mashkoor.qadir]

Dear All,

i am looking for the following problem for the my setup
Internet========>CISCO Firewall ========== >Proxy server =========> Local Area Network

now i want to allow one windows machine to SSH with help of PUTTY to a Linux server that is located in Singapor . I want to allow SSH port22 from proxy Server where as it's allowed from Firewall.. If i am accessing the same machine from firewall i am able to access but when using proxy it doesn't let the traffic go and giving the message the host doesn't exist.
is there any solution.