Proxy 如何为squid配置启动页？

我在配置页面以通过

ubuntu16.04

上的

Squid

重定向第一次访问时遇到问题。下面是

/etc/squid/squid.conf

下的相关配置。我试着从文档和网络中学习这个例子

external_acl_type splash_page %SRC /usr/lib/squid/ext_session_acl -b /var/lib/squid/session.db
acl existing_users external splash_page
deny_info 511:/etc/squid/splash.html existing_users
http_access deny !existing_users

Squid

启动，然后以以下方式存在

# service squid status
● squid.service - LSB: Squid HTTP Proxy version 3.x
   Loaded: loaded (/etc/init.d/squid; bad; vendor preset: enabled)
   Active: active (exited) since dim. 2017-10-29 15:29:47 CET; 1min 8s ago
     Docs: man:systemd-sysv-generator(8)
  Process: 7814 ExecStop=/etc/init.d/squid stop (code=exited, status=0/SUCCESS)
  Process: 4616 ExecReload=/etc/init.d/squid reload (code=exited, status=0/SUCCESS)
  Process: 7833 ExecStart=/etc/init.d/squid start (code=exited, status=0/SUCCESS)

oct. 29 15:29:54 localhost (squid-1)[7913]: The splash_page helpers are crashing too rapidly, need help!
oct. 29 15:29:54 localhost squid[7882]: Squid Parent: (squid-1) process 7913 exited with status 1
oct. 29 15:29:57 localhost squid[7882]: Squid Parent: (squid-1) process 7925 started
oct. 29 15:29:57 localhost (squid-1)[7925]: The splash_page helpers are crashing too rapidly, need help!
oct. 29 15:29:57 localhost squid[7882]: Squid Parent: (squid-1) process 7925 exited with status 1
oct. 29 15:30:00 localhost squid[7882]: Squid Parent: (squid-1) process 7942 started
oct. 29 15:30:00 localhost (squid-1)[7942]: The splash_page helpers are crashing too rapidly, need help!
oct. 29 15:30:00 localhost squid[7882]: Squid Parent: (squid-1) process 7942 exited with status 1
oct. 29 15:30:00 localhost squid[7882]: Squid Parent: (squid-1) process 7942 will not be restarted due to repeated, frequent failures
oct. 29 15:30:00 localhost squid[7882]: Exiting due to repeated, frequent failures

这些文件已经存在，并且（我认为）配置了良好的权限：

# ll /usr/lib/squid/ext_session_acl
-rwxr-xr-x 1 root root 10208 juil. 26 15:11 /usr/lib/squid/ext_session_acl*
# ll /etc/squid/splash.html
-r--r--r-- 1 root root 11 oct.  29 11:18 /etc/squid/splash.html
# ll /var/lib/squid/session.db
-rw-r----- 1 proxy root 1 oct.  29 13:43 /var/lib/squid/session.db

我错过了什么？这是我第一次使用squid，所以我希望我不是在问一个愚蠢的问题