#!/bin/bash
# SSH反向隧道自动重连脚本

# 配置参数
REMOTE_HOST="123.56.98.4"
REMOTE_USER="root"
REMOTE_PORT=22
TUNNEL_PORT=2222
LOCAL_PORT=22
CHECK_INTERVAL=60  # 检查间隔（秒）

echo "=== SSH反向隧道自动重连脚本 ==="
echo "远程服务器: ${REMOTE_USER}@${REMOTE_HOST}:${REMOTE_PORT}"
echo "隧道端口: ${TUNNEL_PORT} -> localhost:${LOCAL_PORT}"
echo "检查间隔: ${CHECK_INTERVAL}秒"
echo ""

# 检查SSH是否安装
if ! command -v ssh &> /dev/null; then
    echo "错误: SSH客户端未安装，请先运行 ssh_tunnel_setup.sh"
    exit 1
fi

# 函数：建立SSH隧道
establish_tunnel() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] 建立SSH反向隧道..."
    
    # 先检查是否已有连接
    PID=$(pgrep -f "ssh.*-R.*${TUNNEL_PORT}:localhost:${LOCAL_PORT}.*${REMOTE_USER}@${REMOTE_HOST}")
    if [ ! -z "$PID" ]; then
        echo "发现已有隧道进程 (PID: $PID)，先关闭..."
        kill $PID 2>/dev/null
        sleep 2
    fi
    
    # 建立新连接
    ssh -fN -R ${TUNNEL_PORT}:localhost:${LOCAL_PORT} \
        -o ServerAliveInterval=30 \
        -o ServerAliveCountMax=3 \
        -o ExitOnForwardFailure=yes \
        -o StrictHostKeyChecking=no \
        -p ${REMOTE_PORT} \
        ${REMOTE_USER}@${REMOTE_HOST}
    
    if [ $? -eq 0 ]; then
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] ✓ 隧道建立成功"
        return 0
    else
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] ✗ 隧道建立失败"
        return 1
    fi
}

# 函数：检查隧道是否存活
check_tunnel() {
    PID=$(pgrep -f "ssh.*-R.*${TUNNEL_PORT}:localhost:${LOCAL_PORT}.*${REMOTE_USER}@${REMOTE_HOST}")
    if [ ! -z "$PID" ]; then
        # 检查进程是否真的在运行
        if ps -p $PID > /dev/null 2>&1; then
            return 0
        fi
    fi
    return 1
}

# 主循环
echo "开始监控SSH隧道..."
establish_tunnel

while true; do
    sleep ${CHECK_INTERVAL}
    
    if ! check_tunnel; then
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] ⚠ 检测到隧道断开，重新连接..."
        establish_tunnel
    else
        echo "[$(date '+%Y-%m-%d %H:%M:%S')] ✓ 隧道连接正常"
    fi
done