How to raise any vpn client/server on VPS with OpenVZ?

Question

linux

There is an OpenVZ VPS with a zabbix server at the host and a number of hosts in the gray network of another data center, the "gray" hosts need to be monitored. Naturally, there are no tun / tap / ppp kernel modules in vps and it is impossible to raise all vpn known to me. The hoster refused to raise the modules (and I understand him).
I cannot use zabbix-proxy due to the need for feedback.
The gray network edge server can be win or lin.

What are the options, if any?

Answer 1

And on TrueVDS, `modeprob tun` worked and activated the module ...
You can connect to the server via ssh from clients and bind the port. And then on the server using iptables, you can redirect the “left” ip with the monitoring port to the port you need.

ssh -NfR 3456:127.0.0.1:80
iptables -t nat -I OUTPUT -d 8.8.7.7 -p tcp --dport 80 -j DNAT --to-destination 127.0.0.1:3456

ssh on the client and iptables on the server. After that, when the server tries to contact 8.8.7.7:80, it will end up on the 80th port of the client. ssh on the client will start as a daemon, so you won't see the shell, but the tunnel will.

Answer 2

Is using active clients not an option?

Answer 3

I don’t know about Zabbix, but in Nagios you can use check_nrpe with a request for a specific port (5666 by default). On the gray server, nrpe is configured, and port forwarding is done on the router, say 56666 goes to the 1st gray server, 56667 to the 1st gray server.