如何在 Ubuntu 16.04 上安裝 Squid (proxy server)

peter279k

[English title：How to install Squid in Ubuntu 16.04 LTS？]

[前言]

因為做論文研究關係，需要用到 Squid 這類的 proxy server 來做網址導向（redirection）的動作。

[環境需求]

本次的Linux Distro：Ubuntu 16.04 LTS

[開始安裝！]

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# 更新套件
 
sudo apt-get update
 
sudo apt-get install squid
 
# 複製一份設定檔，若改錯還可以把設定回復。
 
sudo cp /etc/squid/squid.conf /etc/squid/squid.conf.backup
 
# 編輯 squid.conf
 
sudo vim /etc/squid/squid.conf

[squid.conf 的設定]

這邊只設定成：把指定的網址做重新導向的動作。

那我們是靠著 PHP script 來處理重新導向的動作，squid 會監聽所有的 HTTP 請求。

把他們交給 PHP 之後，接著交由 PHP 執行，接著 PHP 會去跑我們指定的 PHP script ，處理完並得到結果後進行輸出，結束。

以下是 squid.conf 的內容：除了下面有一些客製化的設定之外，基本上可以直接複製拿來做使用的。

我把 configuration (squid.conf) 貼在Gist：

# WELCOME TO SQUID 3.5.12
# ----------------------------
#
# This is the documentation for the Squid configuration file.
# This documentation can also be found online at:
# http://www.squid-cache.org/Doc/config/
#
# You may wish to look at the Squid home page and wiki for the
# FAQ and other documentation:
# http://www.squid-cache.org/
# http://wiki.squid-cache.org/SquidFaq
# http://wiki.squid-cache.org/ConfigExamples
#
# This documentation shows what the defaults for various directives
# happen to be. If you don't need to change the default, you should
# leave the line out of your squid.conf in most cases.
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
# Recommended minimum Access Permission configuration:
#
# 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
# Only allow cachemgr access from localhost
http_access allow localhost manager
http_access deny manager
# Squid normally listens to port 3128
http_port 3128
# TAG: https_port
# If shared memory caching is enabled, Squid does not use the shared
# cache space for in-transit objects, but they still consume as much
# local memory as they need. For more details about the shared memory
# cache, see memory_cache_shared.
#Default:
cache_mem 8 MB
# TAG: maximum_object_size_in_memory (bytes)
# Objects greater than this size will not be attempted to kept in
# the memory cache. This should be set high enough to keep objects
# accessed frequently in memory to improve performance whilst low
# enough to keep larger objects from hoarding cache_mem.
#Default:
maximum_object_size_in_memory 1024 KB
# See also cache_swap_high and cache_replacement_policy
#Default:
cache_swap_low 90
# TAG: cache_swap_high (percent, 0-100)
# See also cache_swap_low and cache_replacement_policy
#Default:
cache_swap_high 95
# Leave coredumps in the first cache dir
coredump_dir /var/spool/squid
# The refresh_pattern lines are checked in the order listed here.
# The first entry which matches is used. If none of the entries
# match the default will be used.
#
# Note, you must uncomment all the default lines if you want
# to change one. The default setting is only active if none is
# used.
#
#
#
# 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 (Release|Packages(.gz)*)$ 0 20% 2880
# example lin deb packages
#refresh_pattern (\.deb|\.udeb)$ 129600 100% 129600
refresh_pattern . 0 20% 4320
# ADMINISTRATIVE PARAMETERS
# -----------------------------------------------------------------------------
# TAG: cache_mgr
# Email-address of local cache manager who will receive
# mail if the cache dies. The default is "webmaster".
cache_mgr peter279k@gmail.com
#Default:
# cache_mgr webmaster
# TAG: visible_hostname
visible_hostname lab223
# TAG: ipcache_size (number of entries)
# Maximum number of DNS IP cache entries.
#Default:
ipcache_size 1024
# TAG: ipcache_low (percent)
#Default:
ipcache_low 90
# TAG: ipcache_high (percent)
# The size, low-, and high-water marks for the IP cache.
#Default:
ipcache_high 95
# TAG: fqdncache_size (number of entries)
# Maximum number of FQDN cache entries.
#Default:
fqdncache_size 1024
# Custom configuration
acl MyNetwork src 192.168.0.1
acl BLKSite dstdomain www.google.com.pa
deny_info https://google.com.tw all
http_reply_access deny BLKSite all
http_access allow MyNetwork
url_rewrite_program /etc/squid/url_redirect.php
url_rewrite_children 5
#http_access deny all
forwarded_for off
request_header_access Allow allow all
request_header_access Authorization allow all
request_header_access WWW-Authenticate allow all
request_header_access Proxy-Authorization allow all
request_header_access Proxy-Authenticate allow all
request_header_access Cache-Control allow all
request_header_access Content-Encoding allow all
request_header_access Content-Length allow all
request_header_access Content-Type allow all
request_header_access Date allow all
request_header_access Expires allow all
request_header_access Host allow all
request_header_access If-Modified-Since allow all
request_header_access Last-Modified allow all
request_header_access Location allow all
request_header_access Pragma allow all
request_header_access Accept allow all
request_header_access Accept-Charset allow all
request_header_access Accept-Encoding allow all
request_header_access Accept-Language allow all
request_header_access Content-Language allow all
request_header_access Mime-Version allow all
request_header_access Retry-After allow all
request_header_access Title allow all
request_header_access Connection allow all
request_header_access Proxy-Connection allow all
request_header_access User-Agent allow all
request_header_access Cookie allow all
request_header_access All deny all
view raw squid.conf hosted with ❤ by GitHub

以及：url_redirect.php (squid.conf 的 134行，使用 PHP script 處理導向)
作用：指的是，若連線到：www.animen.com.tw 就導向到：www.google.com.sa

#!/usr/bin/php
# Squid URL Rewrite program : Codes picked from the internet.
<?php
$temp = array();
while ( $input = fgets(STDIN) ) {
// Split the output (space delimited) from squid into an array.
$temp = split(' ', $input);
// Set the URL from squid to a temporary holder.
$output = $temp[0] . "\n";
// Clean the Requesting IP Address field up.
$ip = split('/',rtrim($temp[1], "/-"));
if (preg_match("/^http:\/\/www.animen.com.tw/i", $temp[0])) {
$output = "301:https://www.google.com.sa/\n";
}
echo $output;
}
view raw url_redirect.php hosted with ❤ by GitHub

[解析]

比較重要的地方是從：#custom configuration 下面開始(在 129 行開始)，裡面有定義一些

requst header, 還有 url_rewrite 等。

  1. 其中的 192.169.0.1 應該要改成你自己當前電腦所使用的 IP。
  2. 如果要用：url_rewrite 把所有的請求都交給 PHP 來做處理的話，129 行到 133 行可以刪除。
    留下 134 以及 135 行即可。
  3. 若不靠 PHP scirpt 處理導向的話，請留下 129 行到 133 行。刪掉或註解 134 跟 135 行。
    129 行請換成當前電腦的 IP address (請用 ifconfig 指令查詢)。
  4. 第 129 行到 133 行，作用：當連到 www.google.com.pa 時，會自動導向到：https://google.com.tw
  5. 若要改 proxy server 的 port number，請參考第 44 行
  6. 第 101 行的 cache_mgr 是管理者 email 當有存取的動作的時候，就可以發信做通知
    當然也要設定與安裝 email server。
  7. 第 106 行的 visible_hostname 則是填寫你主機的 host name
  8. 任何設定完之後，記得要重啟 squid 服務，這樣新的設定才會生效。
  9. 因為會動到 HTTP 應用層上的東西，所以通常重啟服務會稍微久一點，是正常的。
  10. 有用防火牆的話，記得將 port 打開。(如果要允許讓外部連線的話，不用的話，這步就免了。)

[討論＆後記]

雖然有一些方式，像是直接把要導向的 URL 直接的寫在 squid.conf 裡，不過就是我不太熟 bash，再加上要導向的網址很多，想說用 PHP 直接去做掉，會比較快一點。雖然效能會差一點。不過是導向靜態的內容檔案，感覺是還好的。說不定之後就會改成直接在 squid.conf 裡設定，不用 PHP script XD。

[參考資料]

Creating an HTTP Proxy Using Squid on Ubuntu 12.04

SQUID URL Redirection

Squid 官網