82   ESR Series Routers Operation Manual 
7.23  Configuring remote access to corporate network via OpenVPN protocol 
OpenVPN  is  a  sophisticated  tool  based on  SSL  that  implements Virtual  Private  Networks  (VPN), 
enables remote access and solves many different tasks related to data transmission security. 
Objective: Configure Open VPN server in L3 mode on a router for remote user connection to LAN. 
  OpenVPN server subnet: 10.10.100.0/24 
  Mode: L3 
  Authentication based on certificates 
 
 
Fig. 7.24—Network structure 
Solution: 
First, do the following: 
-  Prepare certificates and keys:  
  CA certificate 
  OpenVPN server key and certificate 
  Diffie-Hellman and HMAC key for TLS 
-  Configure zone for te1/0/1 interface 
-  Specify IP address for te1/0/1 interface 
Import certificates and keys via tftp 
esr# copy tftp://192.168.16.10:/ca.crt certificate:ca/ca.crt 
esr# copy tftp://192.168.16.10:/dh.pem certificate:dh/dh.pem 
esr# copy tftp://192.168.16.10:/server.key certificate:server-key/server.key 
esr# copy tftp://192.168.16.10:/server.crt certificate:server-crt/server.crt 
esr# copy tftp://192.168.16.10:/ta.key certificate:ta/ta.key 
Create OPENVPN server and a subnet for its operation: 
esr(config)# remote-access openvpn AP 
esr(config-openvpn)# network 10.10.100.0/24 
Specify L3 connection type and encapsulation protocol. 
esr(config-openvpn)# tunnel ip 
esr(config-openvpn)# protocol tcp 
Announce LAN subnets that will be available via OpenVPN connection and define DNS server 
esr(config-)# route 10.10.0.0/20 
esr(config-openvpn)# dns-server 10.10.1.1