将 Squid 配置为 HTTPS 转发代理？

Question

这是我的问题的一些背景：

• 我有一个在 Heroku 上运行的 Web 服务，具有动态 IP 地址。Heroku 上的静态 IP 不是一种选择。
• 我需要连接到防火墙后面的外部 Web 服务。操作外部 Web 服务的人员只会将防火墙打开到特定的静态 IP。

我尝试的解决方案是在具有静态 IP 的单独服务器上使用 Squid 将代理请求从 Heroku 转发到外部服务。这样，外部服务总是看到代理服务器的静态 IP，而不是 Heroku 服务的动态 IP。

由于我的代理服务器不能依赖 IP 地址进行身份验证（这就是开始的问题！），它必须依赖用户名和密码。此外，用户名和密码不能以明文传输，因为如果攻击者要拦截明文，那么他们可以冒充我连接到我的代理，使用我代理的静态 IP 发出出站请求，从而逃避外部Web 服务的防火墙。

因此，Squid 代理必须只接受通过 HTTPS 的连接，而不是 HTTP。（与外部 Web 服务的连接可能是 HTTP 或 HTTPS。）

我在 CentOS 6.5.x 上运行 Squid 3.1.10，这是我squid.conf目前的情况。仅出于故障排除目的，我暂时启用了 HTTP 和 HTTPS 代理，但我只想使用 HTTPS。

#
# Recommended minimum configuration:
#
acl manager proto cache_object
acl localhost src 127.0.0.1/32 ::1
acl to_localhost dst 127.0.0.0/8 0.0.0.0/32 ::1

# Example rule allowing access from your local networks.
# Adapt to list your (internal) IP networks from where browsing
# should be allowed
acl localnet src 10.0.0.0/8 # RFC1918 possible internal network
acl localnet src 172.16.0.0/12  # RFC1918 possible internal network
acl localnet src 192.168.0.0/16 # RFC1918 possible internal network
acl localnet src fc00::/7       # RFC 4193 local private network range
acl localnet src fe80::/10      # RFC 4291 link-local (directly plugged) machines

acl SSL_ports port 443
acl Safe_ports port 80      # http
acl Safe_ports port 21      # ftp
acl Safe_ports port 443     # https
acl Safe_ports port 70      # gopher
acl Safe_ports port 210     # wais
acl Safe_ports port 1025-65535  # unregistered ports
acl Safe_ports port 280     # http-mgmt
acl Safe_ports port 488     # gss-http
acl Safe_ports port 591     # filemaker
acl Safe_ports port 777     # multiling http
acl CONNECT method CONNECT

# Authorization

auth_param digest program /usr/lib64/squid/digest_pw_auth -c /etc/squid/squid_passwd
auth_param digest children 20 startup=0 idle=1
auth_param digest realm squid
auth_param digest nonce_garbage_interval 5 minutes
auth_param digest nonce_max_duration 30 minutes
auth_param digest nonce_max_count 50

acl authenticated proxy_auth REQUIRED

#
# Recommended minimum Access Permission configuration:
#
# Only allow cachemgr access from localhost
http_access allow manager localhost
http_access deny manager

# Deny requests to certain unsafe ports
http_access deny !Safe_ports

# Deny CONNECT to other than secure SSL ports
http_access deny CONNECT !SSL_ports

# We strongly recommend the following be uncommented to protect innocent
# web applications running on the proxy server who think the only
# one who can access services on "localhost" is a local user
#http_access deny to_localhost

#
# INSERT YOUR OWN RULE(S) HERE TO ALLOW ACCESS FROM YOUR CLIENTS
#

# Example rule allowing access from your local networks.
# Adapt localnet in the ACL section to list your (internal) IP networks
# from where browsing should be allowed
#http_access allow localnet
#http_access allow localhost
http_access allow authenticated

# And finally deny all other access to this proxy
http_access deny all

# Squid normally listens to port 3128
http_port 3128

https_port 3129 cert=/etc/squid/ssl/cert.pem key=/etc/squid/ssl/key.pem

# We recommend you to use at least the following line.
hierarchy_stoplist cgi-bin ?

# Disable all caching
cache deny all

# Uncomment and adjust the following to add a disk cache directory.
#cache_dir ufs /var/spool/squid 100 16 256

# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid

# Add any of your own refresh_pattern entries above these.
refresh_pattern ^ftp:       1440    20% 10080
refresh_pattern ^gopher:    1440    0%  1440
refresh_pattern -i (/cgi-bin/|\?) 0 0%  0
refresh_pattern .       0   20% 4320

使用此设置，HTTP 代理可以正常工作，但 HTTPS 代理不行。

这是来自本地框的 HTTP 代理请求：

$ curl --proxy http://my-proxy-server.example:3128 \
  --proxy-anyauth --proxy-user redacted:redacted -w '\n' \
  http://urlecho.appspot.com/echo?body=OK
OK

很好，这正是我所期望的。这导致一行/var/log/squid/access.log：

1390250715.137     41 my.IP.address.redacted TCP_MISS/200 383 GET http://urlecho.appspot.com/echo? redacted DIRECT/74.125.142.141 text/html

这是另一个请求，这次是使用 HTTPS：

$ curl --proxy https://my-proxy-server.example:3129 \
  --proxy-anyauth --proxy-user redacted:redacted -w '\n' \
  http://urlecho.appspot.com/echo?body=OK

curl: (56) Recv failure: Connection reset by peer

在access.log这之后没有任何内容，但在cache.log：

2014/01/20 20:46:15| clientNegotiateSSL: Error negotiating SSL connection on FD 10: error:1407609C:SSL routines:SSL23_GET_CLIENT_HELLO:http request (1/-1)

再说一遍，更详细地说：

$ curl -v --proxy https://my-proxy-server.example:3129 \
  --proxy-anyauth --proxy-user redacted:redacted -w '\n' \
  http://urlecho.appspot.com/echo?body=OK
* Adding handle: conn: 0x7f9a30804000
* Adding handle: send: 0
* Adding handle: recv: 0
* Curl_addHandleToPipeline: length: 1
* - Conn 0 (0x7f9a30804000) send_pipe: 1, recv_pipe: 0
* About to connect() to proxy my-proxy-server.example port 3129 (#0)
*   Trying proxy.server.IP.redacted...
* Connected to my-proxy-server.example (proxy.server.IP.redacted) port 3129 (#0)
> GET http://urlecho.appspot.com/echo?body=OK HTTP/1.1
> User-Agent: curl/7.30.0
> Host: urlecho.appspot.com
> Accept: */*
> Proxy-Connection: Keep-Alive
> 
* Recv failure: Connection reset by peer
* Closing connection 0

curl: (56) Recv failure: Connection reset by peer

看起来像 SSL 错误。但是，我正在重用一个子域通配符 SSL 证书，在上面的配置中显示为cert.pemand key.pem，我已成功部署在其他 Web 服务器上。此外，使用 curl 直接访问代理服务器是有效的，或者至少建立一个超过 SSL 阶段的连接：

$ curl https://my-proxy-server.example:3129
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html><head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>ERROR: The requested URL could not be retrieved</title>

[--SNIP--]

<div id="content">
<p>The following error was encountered while trying to retrieve the URL: <a href="/">/</a></p>

<blockquote id="error">
<p><b>Invalid URL</b></p>
</blockquote>

<p>Some aspect of the requested URL is incorrect.</p>

<p>Some possible problems are:</p>
<ul>
<li><p>Missing or incorrect access protocol (should be <q>http://</q> or similar)</p></li>
<li><p>Missing hostname</p></li>
<li><p>Illegal double-escape in the URL-Path</p></li>
<li><p>Illegal character in hostname; underscores are not allowed.</p></li>
</ul>

[--SNIP--]

任何想法我做错了什么？我正在尝试的可能吗？提前致谢。

Answer 1

@David，根据您在 Squid ML 中的线程- 我建议使用 Stunnel 解决方案。您的身份验证将是隧道两端的 SSL 证书，其余部分将在该隧道内进行“明文”，或者您可以根据需要进行摘要。

我已经使用类似的解决方案来“验证”NFS 端点，并取得了巨大成功。

这种身份验证的示例使用可以在 LinuxGazette 的Secure Communication with stunnel中看到