PostgreSQL安装后Navicat客户端连接报错：Could not connect to server:Connection refused(0x00002740/10061)
经常使用PostgreSQL数据库的用户，在用Navicat客户端连接服务器端时，报错：
Could not connect to server：Connection refused(0x00002740/10061)
Is the server running on host “xxx.xxx.xx.xx” and accepting
TCP/IP connetions on port 5432?
此问题产生的原因有：
1.host“xxx.xxx.xxx.xxx”不存在，此时客户端ping此IP应不是不通的
2.Host“xxx.xxx.xxx.xxx”存在，客户端ping此Ip地址能ping通，但是此主机并未安装PostgreSQL数据库
以上两个原因好理解，下面还有几个原因，后台查看ps -ef|grep postmaster如下：
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[root@CM-126 pgsql_9.2.2]
# ps -ef|grep postmaster
root 793 32595 0 14:30 pts
/0
00:00:00
grep
postmaster
postgres 32762 1 0 13:50 ? 00:00:00
/usr/local/pgsql/bin/postmaster
-D
/usr/local/pgsql/data
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3.host“xxx.xxx.xxx.xxx”存在，客户端ping此Ip地址能ping通，此主机上也安装了PostgreSQL数据库，监听端口是5432，但客户端填写时而不是5432，如果5432也不正确，就确认下数据库监听的端口，后台用“netstat -anp|grep postmaster”命令查看下
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[root@localhost pgsql]# netstat -anp|grep postmaster
tcp
0
0
0.0
.
0.0
:
5432
0.0
.
0.0
:* LISTEN
14430
/postmaster
tcp
0
0
:::
5432
:::* LISTEN
14430
/postmaster
udp
0
0
127.0
.
0.1
:
1316
127.0
.
0.1
:
1316
ESTABLISHED
14430
/postmaster
unix
2
[ ACC ] STREAM LISTENING
14603833
14430
/postmaster /tmp/.s.PGSQL.
5432
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4.host“xxx.xxx.xxx.xxx”存在，能被客户端ping通，PostgreSQL数据库在主机上已安装，但$PGDATA/data/目录下的配置文件postgresql.conf中关于监听地址配置为：
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listen_addresses =
'localhost'
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或者
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#listen_addresses = '*'
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如果是此种情况，有两种方法可以解决此问题。
第一种：修改配置文件postgresql.conf
此时只需将监听地址改为：
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listen_addresses =
'*'
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然后，重启(/etc/rc.d/init.d/postgresql restart)PostgreSQL即可
第二种：配置文件postgresql.conf不做修改
保持postgresql.conf不变，转而修改PostgreSQL的启动脚本postgresql:
原来启动时命令行为
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su
- $PGUSER -c
"$DAEMON -D '$PGDATA' &"
>>$PGLOG 2>&1
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现改为
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su
- $PGUSER -c
"$DAEMON -i -D '$PGDATA' &"
>>$PGLOG 2>&1
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启动后一般为
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/usr/local/pgsql/bin/postmaster
-i -D
/usr/local/pgsql/data
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启动时加上-i选项，意思就是允许TCP/IP连接
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[root@localhost pgsql]
# /usr/local/pgsql/bin/postmaster --help|grep TCP/IP
-i
enable
TCP
/IP
connections
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5、防火墙开启也会造成此种现象
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[root@cloudera135 ~]
# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt
source
destination
ACCEPT udp -- anywhere anywhere udp dpt:domain
ACCEPT tcp -- anywhere anywhere tcp dpt:domain
ACCEPT udp -- anywhere anywhere udp dpt:bootps
ACCEPT tcp -- anywhere anywhere tcp dpt:bootps
ACCEPT all -- anywhere anywhere state RELATED,ESTABLISHED
ACCEPT icmp -- anywhere anywhere
ACCEPT all -- anywhere anywhere
ACCEPT tcp -- anywhere anywhere state NEW tcp dpt:
ssh
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT)
target prot opt
source
destination
ACCEPT all -- anywhere 192.168.122.0
/24
state RELATED,ESTABLISHED
ACCEPT all -- 192.168.122.0
/24
anywhere
ACCEPT all -- anywhere anywhere
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
REJECT all -- anywhere anywhere reject-with icmp-port-unreachable
REJECT all -- anywhere anywhere reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT)
target prot opt
source
destination
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此种情况若解决，只需关闭防火墙即可
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[root@cloudera135 ~]
# service iptables stop
iptables：清除防火墙规则： [确定]
iptables：将链设置为政策 ACCEPT：nat mangle filter [确定]
iptables：正在卸载模块： [确定]
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若不想关闭防火墙，也可以改变防火墙规则以解决此问题。
注意：3、4两种情况下，$PGDATA/pg_hba.conf文件中的配置为
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# TYPE DATABASE USER ADDRESS METHOD
host all all 0.0.0.0
/0
trust
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