Hi,
i have installed openvpn server in ubuntu 12.04. i am using client centos 6.6 but client machine showing openssl errors. ubuntu 12.04 to ubuntu 14.04 server client authentication working. why centos client side authentication not working

this is my error logs

Jun 14 12:23:12 shekar yum[5231]: Installed: openssl098e-0.9.8e-18.el6_5.2.x86_64
Jun 14 12:23:12 shekar yum[5231]: Installed: openssl-static-1.0.1e-30.el6.9.x86_64
Jun 14 12:24:06 shekar openvpn[5360]: OpenVPN 2.3.6 x86_64-redhat-linux-gnu [SSL (OpenSSL)] [LZO] [EPOLL] [PKCS11] [MH] [IPv6] built on Dec 2 2014
Jun 14 12:24:06 shekar openvpn[5360]: library versions: OpenSSL 1.0.1e-fips 11 Feb 2013, LZO 2.03
Jun 14 12:24:06 shekar openvpn[5360]: WARNING: file 'centos.key' is group or others accessible
Jun 14 12:24:06 shekar openvpn[5360]: Socket Buffers: R=[124928->131072] S=[124928->131072]
Jun 14 12:24:06 shekar openvpn[5360]: failed to find GID for group nogroup
Jun 14 12:24:06 shekar openvpn[5360]: Exiting due to fatal error
Jun 14 12:24:06 shekar openvpn[5363]: Options error: Unrecognized option or missing parameter(s) in login.conf:1: shekar1 (2.3.6)
Jun 14 12:24:06 shekar openvpn[5363]: Use --help for more information.

You should have a group called nogroup, probably with a GID of 65534.

"WARNING: file 'centos.key' is group or others accessible" indicates that centos.key is accessible by more users than is necessary.

You appear to have installed openssl and immediately tried to run it, without any configuration?