I run OpenVPN on my laptop, and move between different physical locations/networks without rebooting my laptop or restarting OpenVPN. All I do is hibernate/unhibernate.
After unhibernate, OpenVPN correctly detects that its "connection" has dropped, and attempts to re-initiate the connection. My config file uses a DNS name for the "remote" option (since the server uses DHCP for its IP, and the hostname is a dyndns hostname). However, the DNS lookup never works if I've moved network locations, since glibc caches the content of /etc/resolv.conf forever, and hence OpenVPN (via glibc) continues to attempt to query the DNS servers from the old physical location/network, which refuse to answer clients at the new location/network, and connectivity may not even be available to such an IP. I believe the fix for this is for OpenVPN to call the "res_init()" function whenever it attempts to restart a broken connection (or at least periodically when doing this) or when DNS lookups fail. This should flush the /etc/resolv.conf cache, pick up the new entries that are relevant to the laptops' new location/network, and everything will be happy. For more (brief) details, see the following bug report: http://sourceware.org/bugzilla/show_bug.cgi?id=3675
