# Listen on 1194 for both IPv4 and IPv6
port 1194
proto udp
proto udp6

# Since we have more than one ip address, this makes openvpn respond with sender addresses
multihome

# We're using the layer 3 tunnel device
dev tun

# Certificates (relative paths work, too)
ca /etc/openvpn/vpnserver/ca.crt
cert /etc/openvpn/vpnserver/aither.inform.hs-hannover.de.crt
key /etc/openvpn/vpnserver/aither.inform.hs-hannover.de.key

# Assume tls server role
tls-server

# Diffie-Hellman parameters
dh /etc/openvpn/vpnserver/dh.pem

# Certificate revocation list
crl-verify /etc/openvpn/vpnserver/crl.pem

# Make sure the client presents a certificate with "client role"
remote-cert-tls client

# Allow multiple connections using the same certificate?
# Currently, we do.
duplicate-cn

# We're using subnet topology
topology subnet

# Use this IPv4 range for clients (/16, so we can cope with all possible clients)
server 10.2.0.0 255.255.0.0

# Use this IPv6 network for clients
server-ipv6 2001:638:614:1750::/64

# Do we need persistence here?
# No, not yet. Probably never.
#ifconfig-pool-persist /etc/openvpn/vpnserver/ipp.txt

# Make sure the client can still reach the OpenVPN server via its default gateway
push "route remote_host 255.255.255.255 net_gateway"

# Push routes for local IPv4 networks
push "route 141.71.30.0 255.255.254.0 vpn_gateway"
push "route 192.168.99.0 255.255.255.0 vpn_gateway"
push "route 10.3.1.0 255.255.255.0 vpn_gateway"
push "route 10.0.0.0 255.255.255.0 vpn_gateway"

# Push the whole /56 block for IPv6
# (The vpn_gateway placeholder does not work here.)
push "route-ipv6 2003:638:614:1700::/56 2001:638:614:1750::1"

# Specific settings regarding TLS, chiphers and hash algorithms
cipher AES-256-GCM
auth SHA256
tls-cipher TLS-ECDHE-RSA-WITH-AES-256-GCM-SHA384
tls-version-min "1.2"

# Make sure to detect broken sessions
keepalive 10 60

# These are needed for reduced privileges? Probably yes.
persist-key
persist-tun

# Reduced privileges
user nobody
group nogroup

# Logging settings
verb 3
mute 5

# Have a status log if needed.
# We do not need it.
# status /etc/openvpn/vpnserver/status.log