OpenVPN >= 2.3 is required

2.2.x branch has a patch[1] that renders tls_serial_* environment variables
in base 16, causing a ValueError exception in ovpn-server hook.

[1] https://github.com/OpenVPN/openvpn/commit/7d5e26cbb53e2700c966e6b6e815f0c824da8956

debian/control

@@ -7,7 +7,7 @@ Standards-Version: 3.9.1
 
 Package: re6stnet
 Architecture: all
-Depends: ${misc:Depends}, python (>= 2.6.6-3), python (<< 2.8), python-argparse, python-openssl (>= 0.13), openvpn (>= 2.1.3), babeld (= 1.6.0-nxd1), iproute2 | iproute, openssl
+Depends: ${misc:Depends}, python (>= 2.6.6-3), python (<< 2.8), python-argparse, python-openssl (>= 0.13), openvpn (>= 2.3), babeld (= 1.6.0-nxd1), iproute2 | iproute, openssl
 Recommends: ${python:Recommends}, logrotate
 Suggests: ndisc6
 Description: resilient, scalable, IPv6 network application

re6stnet.spec

@@ -11,7 +11,7 @@ BuildArch: noarch
 Requires:  babeld = 1.6.0-nxd1
 Requires:  iproute
 Requires:  openssl
-Requires:  openvpn
+Requires:  openvpn >= 2.3
 Requires:  python >= 2.7
 Requires:  pyOpenSSL >= 0.13