问题描述：
squid配置反向代理模式后，启动报错：
[root@019 squid]# service squid start
Starting squid: .................... [FAILED]
检查配置文件：
http_access allow all
# Squid normally listens to port 3128
http_port 20.20.20.19:80 vhost
visible_hostname 019
cache_peer 10.10.10.18 parent 80 0 originserver round-robin
cache_peer 10.10.10.20 parent 80 0 originserver round-robin
查看服务和监听的端口信息
[root@019 squid]# netstat -anpt
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:5901 0.0.0.0:* LISTEN 2007/Xvnc
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 1665/rpcbind
tcp 0 0 0.0.0.0:54192 0.0.0.0:* LISTEN 1708/rpc.statd
tcp 0 0 0.0.0.0:6001 0.0.0.0:* LISTEN 2007/Xvnc
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1905/sshd
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1743/cupsd
tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN 2387/sshd
tcp 0 0 127.0.0.1:6011 0.0.0.0:* LISTEN 2387/sshd
tcp 0 64 10.10.10.19:22 10.10.10.1:57572 ESTABLISHED 2387/sshd
tcp 0 0 :::111 :::* LISTEN 1665/rpcbind
tcp 0 0 :::80 :::* LISTEN 2925/httpd
发现80端口被httpd服务占用
解决办法：
关闭httpd服务，并禁止httpd服务开机自启
[root@019 squid]# service httpd stop
Stopping httpd: [ OK ]
[root@019 squid]# chkconfig httpd off
启动squid服务验证：
[root@019 squid]# service squid start
Starting squid: . [ OK ]
[root@019 squid]# netstat -anpt |grep squid
tcp 0 0 20.20.20.19:80 0.0.0.0:* LISTEN 3054/(squid)
service squid start启动失败：Starting squid: .................... [FAILED]
原文：https://www.cnblogs.com/ccku/p/13635825.html