所以这是一个问题。
我在 Openstack VPS（hostigger，如果这很重要）上安装了 OpenVPN 服务器。我使用了指南https://www.digitalocean.com/community/tutorials/how-to-set-up-an-openvpn-server-on-ubuntu-16-04
到目前为止，一切都很好，我可以建立 VPN 连接。但是当我尝试访问几乎任何网站时，我都遇到了连接超时的情况。
为了调试，我已禁用 ufw。
Iptables：
$ iptables -t nat -v -x -n -L
Chain PREROUTING (policy ACCEPT 43527 packets, 3644888 bytes)
pkts bytes target prot opt in out source destination
Chain INPUT (policy ACCEPT 4095 packets, 441234 bytes)
pkts bytes target prot opt in out source destination
Chain OUTPUT (policy ACCEPT 33 packets, 2279 bytes)
pkts bytes target prot opt in out source destination
Chain POSTROUTING (policy ACCEPT 33 packets, 2279 bytes)
pkts bytes target prot opt in out source destination
1453 104793 MASQUERADE all -- * ens3 10.0.0.0/8 0.0.0.0/0
ens3是我在服务器上的默认界面。
当我尝试tracert从本地机器
$ tracert google.com
Tracing route to google.com [172.217.16.46]
over a maximum of 30 hops:
1 73 ms 73 ms 72 ms 10.8.0.1
2 76 ms 86 ms 75 ms 185.181.208.1
3 74 ms 81 ms 73 ms static-217-195-202-1.fibersunucu.com.tr [217.195.202.1]
4 79 ms 75 ms 74 ms static-177-159-92-77.sadecehosting.net [77.92.159.177]
5 75 ms 75 ms 75 ms 212.156.128.169.static.turktelekom.com.tr [212.156.128.169]
6 74 ms 75 ms 77 ms 00-atakoy-xrs-t2-1---00-atakoy-t3-7.statik.turktelekom.com.tr [212.156.120.130]
7 106 ms 75 ms 74 ms 00-gayrettepe-xrs-t2-1---00-atakoy-xrs-t2-1.statik.turktelekom.com.tr [81.212.203.102]
8 * * 75 ms 00-ebgp-gayrettepe-k---00-gayrettepe-xrs-t2-1.statik.turktelekom.com.tr [81.212.201.195]
9 81 ms 76 ms 75 ms 212.156.120.178.26-eskisehir-t3-1.06-ulus-t3-7.statik.turktelekom.com.tr [212.156.120.178]
10 83 ms 86 ms 83 ms 307-sof-col-1---00-ebgp-gayrettepe-k.statik.turktelekom.com.tr [212.156.104.22]
11 112 ms 103 ms 124 ms 74.125.51.94
12 106 ms 106 ms 111 ms 108.170.250.168
13 145 ms 147 ms 142 ms 108.170.226.42
14 132 ms 132 ms 134 ms 72.14.239.245
15 132 ms 132 ms 132 ms 216.239.58.5
16 136 ms 132 ms 141 ms 108.170.250.193
17 132 ms 132 ms 132 ms 74.125.251.103
18 135 ms 131 ms 132 ms waw02s14-in-f14.1e100.net [172.217.16.46]
Trace complete.
Ping 也有效。
我已经跑了tcpdump
tcpdump -A -s 0 'src president.gov.by and tcp port 80 and (((ip[2:2] - ((ip[0]&0xf)<<2)) - ((tcp[12]&0xf0)>>2)) != 0)'
对于来自本地机器的请求，例如curl -sSL -D - http://president.gov.by/robots.txt- 它有效 - 我看到了 robots.txt
tcpdump 输出：
listening on tun0, link-type RAW (Raw IP), capture size 262144 bytes
23:30:02.115218 IP 178.124.139.203.http > 10.8.0.6.51344: Flags [P.], seq 272799366:272799764, ack 63565427, win 96, length 398: HTTP: HTTP/1.1 200 OK
E.....@./.(..|..
....P...B.....sP..`....HTTP/1.1 200 OK
Server: nginx
Date: Fri, 26 Jul 2019 20:30:02 GMT
Content-Type: text/plain; charset=utf-8
Content-Length: 173
Connection: keep-alive
Last-Modified: Fri, 26 Jul 2019 04:28:06 GMT
Accept-Ranges: bytes
User-agent: *
Disallow: /ru/search_ru
Disallow: /en/search_en
Disallow: /by/search_by
Disallow: /*printv
Host: president.gov.by
Sitemap: http://president.gov.by/sitemap.xml
但当我尝试curl -sSL -D - http://president.gov.by/
我在服务器的 tcpdump 输出中看到此情况，但从未在我的本地机器上看到过：
23:30:39.493302 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 2193652739:2193654079, ack 1503148830, win 96, length 1340: HTTP: HTTP/1.1 200 OK
E..d..@......|..
....P....|.Y.;.P..`)"..HTTP/1.1 200 OK
Server: nginx
Date: Fri, 26 Jul 2019 20:30:39 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 112378
Connection: keep-alive
Last-Modified: Fri, 26 Jul 2019 16:38:45 GMT
Accept-Ranges: bytes
<!DOCTYPE HTML>
<html lang="ru-RU">
<head>
blah-blah-blah some html here
23:30:39.493315 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 1340:2680, ack 1, win 96, length 1340: HTTP
E..d..@......|..
....P.....?Y.;.P..`........................ .................... ................, .. .......... ...................... .................., .........., .............."/>
</head>
<body>
blah-blah-blah some html here
23:30:39.493317 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 2680:4020, ack 1, win 96, length 1340: HTTP
E..d..@......|..
....P.....{Y.;.P..`I".. class="search" id="search_form">
<div class="search_left"></div>
blah-blah-blah some html here
23:30:39.493320 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 4020:5360, ack 1, win 96, length 1340: HTTP
E..d..@......|..
....P......Y.;.P..`...............">..............</a>blah-blah-blah some html here </div>
<div class="top_m
23:30:39.493323 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 5360:6700, ack 1, win 96, length 1340: HTTP
E..d..@......|..
....P......Y.;.P..`/...enu_right"></div>
blah-blah-blah some html here
23:30:39.493325 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 6700:8040, ack 1, win 96, length 1340: HTTP
E..d..@......|..
....P...../Y.;.P..`u>.blah-blah-blah some html here
<div class="bm_da
23:30:39.494547 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [P.], seq 8040:8173, ack 1, win 96, length 133: HTTP
[email protected].|..
....P.....kY.;.P..`....te">25 ........ 2019 ........</div>
<a href="http://president.gov.by/ru/news_ru/view/rabochaja-poezdka-v-vetkovskij-rajon-gomel
23:30:39.633147 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 12193:13533, ack 1, win 96, length 1340: HTTP
[email protected]..|..
....P......Y.;.P..`blah-blah-blah some html here
23:30:40.186755 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 0:1340, ack 1, win 96, length 1340: HTTP: HTTP/1.1 200 OK
[email protected]..|..
....P....|.Y.;.P..`)"..HTTP/1.1 200 OK
Server: nginx
Date: Fri, 26 Jul 2019 20:30:39 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 112378
Connection: keep-alive
Last-Modified: Fri, 26 Jul 2019 16:38:45 GMT
Accept-Ranges: bytes
<!DOCTYPE HTML>
<html lang="ru-RU">
<head>
blah-blah-blah some html here
23:30:41.575025 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 0:1340, ack 1, win 96, length 1340: HTTP: HTTP/1.1 200 OK
[email protected]..|..
....P....|.Y.;.P..`)"..HTTP/1.1 200 OK
Server: nginx
Date: Fri, 26 Jul 2019 20:30:39 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 112378
Connection: keep-alive
Last-Modified: Fri, 26 Jul 2019 16:38:45 GMT
Accept-Ranges: bytes
<!DOCTYPE HTML>
<html lang="ru-RU">
<head>
blah-blah-blah some html here
23:30:44.350585 IP 178.124.139.203.http > 10.8.0.6.51366: Flags [.], seq 0:1340, ack 1, win 96, length 1340: HTTP: HTTP/1.1 200 OK
[email protected]..|..
....P....|.Y.;.P..`)"..HTTP/1.1 200 OK
Server: nginx
Date: Fri, 26 Jul 2019 20:30:39 GMT
Content-Type: text/html; charset=utf-8
Content-Length: 112378
Connection: keep-alive
Last-Modified: Fri, 26 Jul 2019 16:38:45 GMT
Accept-Ranges: bytes
<!DOCTYPE HTML>
<html lang="ru-RU">
<head>
blah-blah-blah some html here
^C
11 packets captured
15 packets received by filter
3 packets dropped by kernel
我被困在这里。为什么我能访问 robots.txt，却不能访问更大的文件（index.html 等）