Remove support for old distros

The following versions are no longer supported:
- Debian 10
- Ubuntu 18.04
- Ubuntu 20.04
- CentOS/Alma/Rocky 7
- CentOS/Alma/Rocky 8
- Fedora 31

openvpn-install.sh

@@ -14,12 +14,6 @@ fi
 # Discard stdin. Needed when running from an one-liner which includes a newline
 read -N 999999 -t 0.001
 
-# Detect OpenVZ 6
-if [[ $(uname -r | cut -d "." -f 1) -eq 2 ]]; then
-	echo "The system is running an old kernel, which is incompatible with this installer."
-	exit
-fi
-
 # Detect OS
 # $os_version variables aren't always in use, but are kept here for convenience
 if grep -qs "ubuntu" /etc/os-release; then
@@ -44,8 +38,8 @@ Supported distros are Ubuntu, Debian, AlmaLinux, Rocky Linux, CentOS and Fedora.
 	exit
 fi
 
-if [[ "$os" == "ubuntu" && "$os_version" -lt 1804 ]]; then
+if [[ "$os" == "ubuntu" && "$os_version" -lt 2204 ]]; then
-	echo "Ubuntu 18.04 or higher is required to use this installer.
+	echo "Ubuntu 22.04 or higher is required to use this installer.
 This version of Ubuntu is too old and unsupported."
 	exit
 fi
@@ -55,15 +49,15 @@ if [[ "$os" == "debian" ]]; then
 		echo "Debian Testing and Debian Unstable are unsupported by this installer."
 		exit
 	fi
-	if [[ "$os_version" -lt 9 ]]; then
+	if [[ "$os_version" -lt 11 ]]; then
-		echo "Debian 9 or higher is required to use this installer.
+		echo "Debian 11 or higher is required to use this installer.
 This version of Debian is too old and unsupported."
 		exit
 	fi
 fi
 
-if [[ "$os" == "centos" && "$os_version" -lt 7 ]]; then
+if [[ "$os" == "centos" && "$os_version" -lt 9 ]]; then
-	echo "CentOS 7 or higher is required to use this installer.
+	echo "CentOS 9 or higher is required to use this installer.
 This version of CentOS is too old and unsupported."
 	exit
 fi
@@ -231,8 +225,8 @@ LimitNPROC=infinity" > /etc/systemd/system/openvpn-server@server.service.d/disab
 		apt-get update
 		apt-get install -y --no-install-recommends openvpn openssl ca-certificates $firewall
 	elif [[ "$os" = "centos" ]]; then
-		yum install -y epel-release
+		dnf install -y epel-release
-		yum install -y openvpn openssl ca-certificates tar $firewall
+		dnf install -y openvpn openssl ca-certificates tar $firewall
 	else
 		# Else, OS must be Fedora
 		dnf install -y openvpn openssl ca-certificates tar $firewall
@@ -260,7 +254,7 @@ LimitNPROC=infinity" > /etc/systemd/system/openvpn-server@server.service.d/disab
 	# Without +x in the directory, OpenVPN can't run a stat() on the CRL file
 	chmod o+x /etc/openvpn/server/
 	# Generate key for tls-crypt
-	openvpn --genkey --secret /etc/openvpn/server/tc.key
+	openvpn --genkey secret /etc/openvpn/server/tc.key
 	# Create the DH parameters file using the predefined ffdhe2048 group
 	echo '-----BEGIN DH PARAMETERS-----
 MIIBCAKCAQEA//////////+t+FRYortKmq/cViAnPTzx2LnFg84tNpWp4TZBFGQz
@@ -405,13 +399,7 @@ WantedBy=multi-user.target" >> /etc/systemd/system/openvpn-iptables.service
 	if sestatus 2>/dev/null | grep "Current mode" | grep -q "enforcing" && [[ "$port" != 1194 ]]; then
 		# Install semanage if not already present
 		if ! hash semanage 2>/dev/null; then
-			if [[ "$os_version" -eq 7 ]]; then
-				# Centos 7
-				yum install -y policycoreutils-python
-			else
-				# CentOS 8 or Fedora
 				dnf install -y policycoreutils-python-utils
-			fi
 		fi
 		semanage port -a -t openvpn_port_t -p "$protocol" "$port"
 	fi
@@ -553,7 +541,7 @@ else
 					apt-get remove --purge -y openvpn
 				else
 					# Else, OS must be CentOS or Fedora
-					yum remove -y openvpn
+					dnf remove -y openvpn
 					rm -rf /etc/openvpn/server
 				fi
 				echo