使用psql链接postgresql服务失败，telnet这个地址和端口有没有反映。
scutech@infokist:~$ psql -h 192.168.17.40 -U scutech -d test psql: could not connect to server: Connection refused Is the server running on host "192.168.17.40" and accepting TCP/IP connections on port 5432? scutech@infokist:~$ telnet 192.168.17.40 5432 Trying 192.168.17.40... telnet: Unable to connect to remote host: Connection refused
从提示看，端口显然没有被侦听，修改postgresql.conf ，把要侦听的地址改成’*’ ，不然它只侦听127.0.0.1。
root@scutech:/etc/postgresql/12/main# vi postgresql.conf .... listen_addresses = '*' # what IP address(es) to listen on;
重新启动服务，发现之前只侦听127.0.0.1，现在ip v4 和v6都听。
root@scutech:/etc/postgresql/12/main# netstat -natp|grep postgre tcp 0 0 127.0.0.1:5432 0.0.0.0:* LISTEN 14123/postgres root@scutech:/etc/postgresql/12/main# service postgresql restart root@scutech:/etc/postgresql/12/main# netstat -natp|grep postgre tcp 0 0 0.0.0.0:5432 0.0.0.0:* LISTEN 14221/postgres tcp6 0 0 :::5432 :::* LISTEN 14221/postgres root@scutech:/etc/postgresql/12/main#
再连接进来发现连接已经通了，是主机信任的问题
scutech@infokist:~$ psql -h 192.168.17.40 -U scutech -d test psql: FATAL: no pg_hba.conf entry for host "192.168.87.155", user "scutech", database "test", SSL on FATAL: no pg_hba.conf entry for host "192.168.87.155", user "scutech", database "test", SSL off scutech@infokist:~$
修改pg_hba.conf ，把ip v4 对应的一行从127.0.0.1改重all，即所有主机。
#host all all 127.0.0.1/32 md5 host all all all md5
重新启动后连接成功
scutech@infokist:~$ psql -h 192.168.17.40 -U scutech -d test Password for user scutech: psql (9.5.21, server 12.3 (Ubuntu 12.3-1.pgdg18.04+1)) WARNING: psql major version 9.5, server major version 12. Some psql features might not work. SSL connection (protocol: TLSv1.2, cipher: ECDHE-RSA-AES256-GCM-SHA384, bits: 256, compression: off) Type "help" for help. test=>
