From 7023e2a5e9646f1428e427ef819ce38ef1c6ad68 Mon Sep 17 00:00:00 2001
From: "iVampireSP.com" <im@ivampiresp.com>
Date: Wed, 12 Jul 2023 18:14:50 +0800
Subject: [PATCH] Create port-forward.sh

---
 port-forward.sh | 121 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 121 insertions(+)
 create mode 100644 port-forward.sh

diff --git a/port-forward.sh b/port-forward.sh
new file mode 100644
index 0000000..8941afd
--- /dev/null
+++ b/port-forward.sh
@@ -0,0 +1,121 @@
+#!/bin/bash
+
+if [[ $# -lt 3 ]]; then
+    echo "参数错误！请提供正确的网卡名称、网络段、起始端口和每个主机号的端口数量，本机 IP。如果需要测试模式，请在最后加上 test_mode 参数。"
+    echo "示例：sudo bash $0 eth0 192.168.0.0/24 21000 10"
+    exit 1
+fi
+
+# 解析网络段、起始端口和每个主机号的端口数量
+subnet=$2
+startPort=$3
+portPerHost=$4
+device=$1
+
+# 检测网络段是否 CIDR
+if [[ $subnet != *"/"* ]]; then
+    echo "网络段必须是 CIDR 格式！"
+    exit 1
+fi  
+
+
+# 验证起始端口和每个主机号的端口数量大于等于0
+if [[ $startPort -lt 0 || $portPerHost -lt 0 ]]; then
+    echo "起始端口和每个主机号的端口数量必须大于等于0！"
+    exit 1
+fi
+
+
+# 传递的参数：IP地址和起始端口号
+ip=$2
+echo "CIDR 是 ${ip}。"
+
+iptables -t nat -A POSTROUTING -s ${ip} -o ${device} -j MASQUERADE
+
+# 去除 ip 的主机号和网段
+ip=${ip%.*}
+
+# portPerHost + 1
+portPerHost=$((portPerHost + 1))
+
+# 启用IP转发
+echo 1 > /proc/sys/net/ipv4/ip_forward
+
+# 清除旧的iptables规则
+iptables -t nat -F
+iptables -t nat -X
+iptables -t nat -Z
+iptables -F
+iptables -X
+iptables -Z
+
+# 设置默认策略
+iptables -P INPUT ACCEPT
+iptables -P FORWARD ACCEPT
+iptables -P OUTPUT ACCEPT
+
+# 计算每个主机号的端口范围
+function calculatePortRanges() {
+    hostNumber=$1
+
+    startPortNumber=$((startPort + (hostNumber * portPerHost)))
+    endPortNumber=$((startPortNumber + portPerHost - 1))
+
+    echo "IP地址 ${ip}.${hostNumber} 对应的端口范围是 ${startPortNumber} 到 ${endPortNumber}。"
+}
+
+# 创建新的iptables规则
+function createPortForwardingRule() {
+    set -x
+
+    hostNumber=$1
+
+    startPortNumber=$((startPort + (hostNumber * portPerHost)))
+    endPortNumber=$((startPortNumber + portPerHost - 1))
+
+    echo "IP ${ip}.${hostNumber} 的 SSH 端口是 ${startPortNumber}。"
+    # SSH端口转发
+    # iptables -t nat -A PREROUTING -p tcp --dport 22 -j DNAT --to-destination ${ip}.${hostNumber}:${startPortNumber}
+    # iptables -t nat -A POSTROUTING -p tcp -d ${ip}.${hostNumber} --dport ${startPortNumber} -j SNAT --to-source ${ip}
+    iptables -t nat -A PREROUTING -i ${device} -p tcp --dport ${startPortNumber} -j DNAT --to ${ip}.${hostNumber}:22
+    iptables -t nat -A PREROUTING -i ${device} -p udp --dport ${startPortNumber} -j DNAT --to ${ip}.${hostNumber}:22
+
+    # RDP端口转发
+    echo "IP ${ip}.${hostNumber} 的 RDP 端口是 $((startPortNumber + 1))。"
+    # iptables -t nat -A PREROUTING -p tcp --dport 3389 -j DNAT --to-destination ${ip}.${hostNumber}:$((startPortNumber + 1))
+    # iptables -t nat -A POSTROUTING -p tcp -d ${ip}.${hostNumber} --dport $((startPortNumber + 1)) -j SNAT --to-source ${ip}
+    iptables -t nat -A PREROUTING -i ${device} -p tcp --dport $((startPortNumber + 1)) -j DNAT --to ${ip}.${hostNumber}:3389
+    iptables -t nat -A PREROUTING -i ${device} -p udp --dport $((startPortNumber + 1)) -j DNAT --to ${ip}.${hostNumber}:3389
+
+    # 实际端口范围转发
+    # iptables -t nat -A PREROUTING -p tcp --dport $((startPortNumber + 2)):$endPortNumber -j DNAT --to-destination ${ip}.${hostNumber}:$((startPortNumber + 2))
+    # iptables -t nat -A POSTROUTING -p tcp -d ${ip}.${hostNumber} --dport $((startPortNumber + 2)) -j SNAT --to-source ${ip}
+    # iptables -t nat -A PREROUTING -i ${device} -p all -d ${ip}.${hostNumber} --dport 10000:10999 -j DNAT --to 172.22.161.170:10000-10999
+
+    startPortNumber=$((startPortNumber + 2))
+    echo "起始端口号是 ${startPortNumber}。"
+    endPortNumber=$((endPortNumber))
+    echo "结束端口号是 ${endPortNumber}。"
+
+    # 实际端口范围转发
+    for ((portNumber = startPortNumber; portNumber <= endPortNumber; portNumber++)); do
+        echo "IP ${ip}.${hostNumber} 的端口是 ${portNumber}。"
+        iptables -t nat -A PREROUTING -i ${device} -p tcp --dport ${portNumber} -j DNAT --to ${ip}.${hostNumber}:${portNumber}
+        iptables -t nat -A PREROUTING -i ${device} -p udp --dport ${portNumber} -j DNAT --to ${ip}.${hostNumber}:${portNumber}
+    done
+    
+    set +x
+
+}
+
+# 循环遍历主机号
+for hostNumber in $(seq 1 254); do
+    if [ "$5" == "test_mode" ]; then
+        calculatePortRanges $hostNumber
+    else
+        createPortForwardingRule $hostNumber
+    fi
+done
+
+# 保存iptables规则
+iptables-save > /etc/iptables.rules