最近想起nas的公网访问一直是个问题。中转网络一直不通畅，如果走公网转nas又会过度暴露而被自动扫描攻击,导致硬盘频繁唤醒。
这里实现一套方案，利用公网服务器的ip进行流量转发，并且添加一道简单的防火墙来过滤网络扫描。可以在回家以后自行将流量切换到内网。
在使用公网ip转发的时候，流量和带宽受公网服务器上限所限制。在家中互联场景，本地路由器可以通过拦截公网ip流量，自动转发到nas。免去内外网ip来回切换的问题。
graph TD
User1(["User1/Phone/PC"]) -->|Access from local NetWork| B{Router}
NAS["NAS lisening:5000(http)/5001(https)"] <-->|In local NetWork| B{Router}
Internet{Internet} <--> PubServer[PubServer onPort:80/443/5001]
Internet <--> B{Router}
User2(["User2/DS File/Photo"]) --> |Access to PubServer:5001| PubServer
主要有以下几个部分实现：
在nas上，将本地端口5000映射到公网ip上，通过 ssh -R 转发。
在计划任务中添加一个bash脚本，建立公网服务器的ssh连接用于端口转发，并设置为开机启动。内容如下：
#!/bin/bash
while true; do
sleep 1
echo "Start Port Forward 5000 @ " `date`
ssh -R 5000:127.0.0.1:5000 yourAccount@YourServer.com -C -q -N -o ServerAliveInterval=60 -o ServerAliveCountMax=10
echo "End of Port Forward 5000 @ " `date`
done;
该脚本启动后会将公网服务器所有来自5000端口的流量转发到nas本身。
5000端口为nas的http服务的连接端口，5001端口为nas的https服务的连接端口。
接下来在公网服务器上配置nginx来实现http流量转发并且配置https端口为5001，通过白名单机制将流量转发到nas。
server {
server_name yourServerName;
location / {
# set $pass_url http://127.0.0.1:8000; # for enter password.
# if ( $http_user_agent ~ 'Synology-' ) {
# // we can also use UA to imp more filters.
set $pass_url http://127.0.0.1:5000;
# }
proxy_pass $pass_url;
proxy_set_header Host $host:80;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
include <your_list_path>/nas_allow_list.conf;
deny all;
}
location /log { //
set $pass_url http://127.0.0.1:8000; # for enter password
proxy_pass $pass_url;
proxy_set_header Host $host:80;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
listen 443 ssl; # managed by Certbot
listen 5001 ssl; # managed by Certbot
<the ssh certs config >
}
在上述conf中/log访问点的流量反代到白名单配置程序，可以用于动态更新 nas_allow_list.conf白名单。
一个简单的基于白名单配置程序：
from werkzeug.wrappers import Request, Response
import subprocess
@Request.application
def application(request):
auth_html = '''<body style="margin: 0;"><div style="margin: auto ; width: 100%; height:100%; border: 2px solid green; padding: 50px 0; text-align: center; "><form method="POST">
<input type="password" name="psw" style="line-height: 25px;" value="" required placehold="Enter Text..." />
<input type="submit" style="width: 90px;height: 30px;" value="Submit" />
</form></div>'''
if request.method != "POST":
return Response(auth_html, content_type="text/html")
data = request.get_data(cache=False,parse_form_data=True)
input = request.form.get("psw", None)
if input != "<Your Pass Word>":
return Response(auth_html[:-6] + "<red>N/a</red></div>", content_type="text/html")
iplist = ",".join(request.access_route)
if request.remote_addr == "127.0.0.1": // the traffic is came from nginx.
record_addr = request.access_route
else:
record_addr = [request.remote_addr]
for ipaddr in record_addr:
ipaddr = ''.join(i for i in ipaddr if i in '0123456789.')
# also we can use firewall to filter te trific
#cmd = ["firewall-cmd","--zone=sszone","--add-source="+ipaddr+"/32"]
cmd = ["bash","-c", "echo 'allow "+ipaddr+";'>> <your_list_path>/nas_allow_list.conf"]
subprocess.check_call(cmd)
cmd = ["nginx", "-s", "reload"]
subprocess.check_call(cmd)
return Response("<h1>You are grand to access, IP<" + iplist + "> has record.<h1>")
if __name__ == "__main__":
from werkzeug.serving import run_simple
run_simple("0.0.0.0", 8000, application, threaded=True)
在路由器配置iptables ， 将内网client到公网服务器的流量直接转发到local nas:
iptables -t nat -A PREROUTING -d <yourPubServerIP> -p tcp --dport 5001 -j DNAT --to-destination <yourLocalNasIP>:5001
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