Added SSH server creation script.

ssh/create_server.sh

@@ -0,0 +1,136 @@
+#!/usr/bin/env bash
+
+# Exit immediately if a command exits with a non-zero status
+set -e
+
+if [ "$EUID" -ne 0 ]; then
+  echo "Error: This script must be run as root."
+  exit 1
+fi
+
+if ! command -v systemctl >/dev/null 2>&1; then
+  echo "Error: systemd is not installed or running. This script requires systemd for auto-restarts."
+  exit 1
+fi
+
+INSTANCE_NAME=$1
+if [ -z "$INSTANCE_NAME" ]; then
+  echo "Usage: $0 <instance_name>"
+  exit 1
+fi
+
+# Locate the sshd binary
+SSHD_BIN=$(command -v sshd || echo "/usr/sbin/sshd")
+if [ ! -x "$SSHD_BIN" ]; then
+  echo "Error: sshd binary not found. Please install OpenSSH."
+  exit 1
+fi
+
+BASE_DIR="/opt/custom_sshd/$INSTANCE_NAME"
+CONFIG_FILE="$BASE_DIR/sshd_config"
+SERVICE_NAME="custom-sshd-${INSTANCE_NAME}.service"
+SERVICE_FILE="/etc/systemd/system/$SERVICE_NAME"
+
+if [ -d "$BASE_DIR" ] || [ -f "$SERVICE_FILE" ]; then
+  echo "Error: An instance or service named '$INSTANCE_NAME' already exists."
+  exit 1
+fi
+
+echo "Creating isolated environment for '$INSTANCE_NAME'..."
+mkdir -p "$BASE_DIR"
+
+# Port detection function
+is_port_in_use() {
+    local port=$1
+    if command -v ss >/dev/null 2>&1; then
+        ss -tln | grep -q ":${port}\b"
+    elif command -v netstat >/dev/null 2>&1; then
+        netstat -tln | grep -q ":${port}\b"
+    else
+        (echo >/dev/tcp/127.0.0.1/${port}) >/dev/null 2>&1
+    fi
+}
+
+# Find the next available port starting from 2222
+PORT=2222
+while is_port_in_use $PORT; do
+  PORT=$((PORT+1))
+done
+echo "Found available port: $PORT"
+
+# Generate isolated Host Keys
+echo "Generating host keys..."
+ssh-keygen -t rsa -b 4096 -f "$BASE_DIR/ssh_host_rsa_key" -N "" -q
+ssh-keygen -t ed25519 -f "$BASE_DIR/ssh_host_ed25519_key" -N "" -q
+
+# Generate the isolated sshd_config
+cat <<EOF > "$CONFIG_FILE"
+Port $PORT
+HostKey $BASE_DIR/ssh_host_rsa_key
+HostKey $BASE_DIR/ssh_host_ed25519_key
+
+# Security & Authentication defaults
+PermitRootLogin prohibit-password
+PasswordAuthentication yes
+PubkeyAuthentication yes
+AuthorizedKeysFile .ssh/authorized_keys
+
+# Subsystem configuration
+Subsystem sftp internal-sftp
+EOF
+
+# Firewall configuration function
+open_firewall_port() {
+    local p=$1
+    echo "Configuring firewall for port $p..."
+    if command -v firewall-cmd >/dev/null 2>&1 && systemctl is-active --quiet firewalld; then
+        firewall-cmd --permanent --add-port=${p}/tcp >/dev/null
+        firewall-cmd --reload >/dev/null
+        echo " -> Opened port $p using firewalld."
+    elif command -v ufw >/dev/null 2>&1 && ufw status | grep -q "Status: active"; then
+        ufw allow ${p}/tcp >/dev/null
+        echo " -> Opened port $p using ufw."
+    elif command -v iptables >/dev/null 2>&1; then
+        iptables -I INPUT -p tcp --dport ${p} -j ACCEPT
+        echo " -> Opened port $p using iptables (Note: this rule won't survive a reboot without iptables-persistent)."
+    else
+        echo " -> Warning: No supported active firewall found. Port $p might need manual opening."
+    fi
+}
+
+open_firewall_port $PORT
+
+# Generate the systemd service file
+echo "Creating systemd service: $SERVICE_NAME..."
+cat <<EOF > "$SERVICE_FILE"
+[Unit]
+Description=Custom SSHd instance ($INSTANCE_NAME)
+After=network.target auditd.service
+
+[Service]
+# -D prevents sshd from detaching, which systemd prefers for standard services
+ExecStart=$SSHD_BIN -D -f $CONFIG_FILE
+ExecReload=/bin/kill -HUP \$MAINPID
+KillMode=process
+Restart=on-failure
+RestartSec=5s
+
+[Install]
+WantedBy=multi-user.target
+EOF
+
+# Enable and start the service
+echo "Starting and enabling the service..."
+systemctl daemon-reload
+systemctl enable --now "$SERVICE_NAME"
+
+echo "----------------------------------------------------"
+echo "Success! SSH Server '$INSTANCE_NAME' is running and will auto-restart."
+echo "Port: $PORT"
+echo "Config: $CONFIG_FILE"
+echo "Service: $SERVICE_NAME"
+echo ""
+echo "To check status: systemctl status $SERVICE_NAME"
+echo "To view logs: journalctl -u $SERVICE_NAME -f"
+echo "To completely remove: systemctl disable --now $SERVICE_NAME && rm $SERVICE_FILE && rm -rf $BASE_DIR"
+echo "----------------------------------------------------"