====== Bob's VPN setup ======
  - On mac, in /Users/rim/easy-rsa/2.0 
      * source ./vars 
      * ./build-key <client-name> 
  - Move cert files to sc1.snu.ac.kr:/etc/openvpn 
  - Give user a copy of <client-name>.crt, <client-name>.key and ca.crt 
  - If fixed address required, in sc1.snu.ac.kr:/etc/openvpn/ccd 
      * create file <client-name>, containing ifconfig-push 10.160.81.x 10.160.81.y, where x and y are taken from 
          * [1,2] [5,6] [9,10] [13,14] [17,18]
          * [21,22] [25,26] [29,30] [33,34] [37,38] 
          * .
          * .
          * .
          * [241,242] [245,246] [249,250] [253,254] 
          * Note: only needed for machines which require a fixed addr 
          * Note: need to be careful not to double-allocate 
      * Tell user their address, 10.161.81.x