Strato vServer 內的 VPN 伺服器

我有一個執行 Ubuntu 18 作業系統的Strato vServer，我嘗試使用本指南在此伺服器上安裝 VPN 伺服器。但是執行後我收到以下錯誤消息service openvpn@server restart：

Aug  6 23:39:19 systemd[1]: Started OpenVPN connection to server.
Aug  6 23:39:19 ovpn-server[31964]: Diffie-Hellman initialized with 2048 bit key
Aug  6 23:39:19 ovpn-server[31964]: Outgoing Control Channel Authentication: Using 256 bit message hash 'SHA256' for HMAC authentication
Aug  6 23:39:19 ovpn-server[31964]: Incoming Control Channel Authentication: Using 256 bit message hash 'SHA256' for HMAC authentication
Aug  6 23:39:19 ovpn-server[31964]: TUN/TAP device tap0 opened
Aug  6 23:39:19 ovpn-server[31964]: Note: Cannot set tx queue length on tap0: Operation not permitted (errno=1)
Aug  6 23:39:19 ovpn-server[31964]: do_ifconfig, tt->did_ifconfig_ipv6_setup=0
Aug  6 23:39:19 ovpn-server[31964]: /sbin/ip link set dev tap0 up mtu 1500
Aug  6 23:39:19 ovpn-server[31964]: openvpn_execve: unable to fork: Resource temporarily unavailable (errno=11)
Aug  6 23:39:19 ovpn-server[31964]: Exiting due to fatal error
Aug  6 23:39:19 systemd-udevd[31965]: link_config: autonegotiation is unset or enabled, the speed and duplex are not writable.
Aug  6 23:39:19 systemd-udevd[31965]: link_config: could not get ethtool features for tap0
Aug  6 23:39:19 systemd-udevd[31965]: Could not set offload features of tap0: No such device
Aug  6 23:39:19 systemd[1]: openvpn@server.service: Main process exited, code=exited, status=1/FAILURE
Aug  6 23:39:19 systemd[1]: openvpn@server.service: Failed with result 'exit-code'.

所以它似乎tap0不存在。但是為什麼它失去了，我該如何添加它？

這是關於LimitNPROC設置的。你得到目前值

systemctl show openvpn@server --property=LimitNPROC

您可以通過將其添加到單元文件來解決問題

[Service]
LimitNPROC=infinity

然後systemctl daemon-reload在重啟 OpenVPN 服務之前執行。

引用自：https://unix.stackexchange.com/questions/603238