CURL ERROR 7 Failed to connect to Permission denied

“CURL ERROR 7 Failed to connect to Permission denied” error is caused, when for any reason curl request is blocked by some firewall or similar thing.

you will face this issue when ever the curl request is not with standard ports.

for example if you do curl to some URL which is on port 1234, you will face this issue where as URL with port 80 will give you results easily.

Most commonly this error has been seen on CentOS and any other OS with ‘SElinux’.

you need to either disable or change  ‘SElinux’ to permissive

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nano /etc/selinux/config

locate following line

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SELINUX=enforcing

Change this to

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SELINUX=disabled

reboot is needed

新安装完CentOS Linux，发现配置完apache后没法访问，估计是防火墙问题。

　　/etc/init.d/iptables status

　　会得到一系列信息，说明防火墙开着。

　　/etc/init.d/iptables stop

　　永久关闭:

　　chkconfig --level 35 iptables off

永久关闭SELinux

查看当前SELinux状态：
/usr/bin/setstatus -v

编辑/etc/selinux/config，找到SELINUX 行修改成为：SELINUX=disabled:

# This file controls the state of SELinux on the system. 
# SELINUX= can take one of these three values: 
# enforcing - SELinux security policy is enforced. 
# permissive - SELinux prints warnings instead of enforcing. 
# disabled - No SELinux policy is loaded. 
SELINUX=disabled 
# SELINUXTYPE= can take one of these two values: 
# targeted - Only targeted network daemons are protected. 
# strict - Full SELinux protection. 
SELINUXTYPE=targeted 

重启系统。

Centos还提供了实时改变SELinux工作模式的工具，前提是SELinux没有被disabled掉的时候

/usr/sbin/setenforce 0 #使SELinux工作模式变成permissive模式
/usr/sbin/setenforce 1 #使SELinux工作模式变成enforcing模式

添加到系统默认启动脚本里面
echo "/usr/sbin/setenforce 0" >> /etc/rc.local

这样就可以实时控制SELinux的启用和不启用了。

三个参数介绍介绍

• enforcing — The SELinux security policy is enforced.

• permissive — The SELinux system prints warnings but does not enforce policy.

• disabled — SELinux is fully disabled. SELinux hooks are disengaged from the kernel and the pseudo-file system is unregistered. 
  

简单翻译：
enforcing模式：强制组织。
permissive模式：SELinux系统输出警告，但是不强制阻止程序运行。
disabled模式：关闭模式