Oracle sqlnet.ora, tnsnames.ora, listener.ora

1. %ORACLE_HOME%/NETWORK/ADMIN/sqlnet.ora

# sqlnet.ora Network Configuration File: D:\Oracle\product\11.1.0\db_1\NETWORK\ADMIN\sqlnet.ora
# Generated by Oracle configuration tools.

# This file is actually generated by netca. But if customers choose to 
# install "Software Only", this file wont exist and without the native 
# authentication, they will not be able to connect to the database on NT.

SQLNET.AUTHENTICATION_SERVICES = (BEQ, NONE)
NAMES.DIRECTORY_PATH = (TNSNAMES, HOSTNAME)

# TCP.INVITED_NODES = (127.0.0.1,192.168.1.1)
# TCP.EXCLUDED_NODES = (192.168.1.2)
# TCP.VALIDNODE_CHECKING = yes

# NAMES.DIRECTORY_PATH = (TNSNAMES, HOSTNAME)
这个参数用来决定oracle如何解析连接字符串，其中 TNSNAMES 表示优先在 tnsnames.ora 查找相应的字符串信息；如果未找到相应记录，那么再通过 HOSTNAME 的方式进行解析。例如：
sqlplus scott/tiger@local # TNSNAMES 的方式
sqlplus scott/tiger@//ip:port/serviceName # HOSTNAME 的方式

# TCP.INVITED_NODES = (127.0.0.1,192.168.1.1)
这个参数表示允许进行访问的客户端ip

# TCP.EXCLUDED_NODES = (192.168.1.2)
这个参数表示不允许进行访问的客户端ip

# TCP.VALIDNODE_CHECKING = yes
这个参数表示启用上面两个参数

2. %ORACLE_HOME%/NETWORK/ADMIN/tnsnames.ora

# tnsnames.ora Network Configuration File: D:\Oracle\product\11.1.0\db_1\network\admin\tnsnames.ora
# Generated by Oracle configuration tools.

local =
  (DESCRIPTION =
    (ADDRESS_LIST = 
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
    )
    (CONNECT_DATA =
      (SERVER = DEDICATED)
      (SERVICE_NAME = ORCL1)
    )
  )

# 这个文件只在本地使用，其作用类似于windows中的hosts文件，相当于一个字符串替换。
sqlplus scott/tiger@local
等同于
sqlplus scott/tiger@(DESCRIPTION=(ADDRESS_LIST=(ADDRESS=(PROTOCOL=TCP)(HOST=127.0.0.1)(PORT=1521)))(CONNECT_DATA=(SERVER=DEDICATED)(SERVICE_NAME=ORCL1)))

# local 表示一个别名，用户可以自定义

3. %ORACLE_HOME%/NETWORK/ADMIN/listener.ora

# listener.ora Network Configuration File: D:\Oracle\product\11.1.0\db_1\network\admin\listener.ora
# Generated by Oracle configuration tools.

SID_LIST_LISTENER =
  (SID_LIST =
    (SID_DESC =
      (GLOBAL_DBNAME = ORCL1)
      (SID_NAME = ORCL)
      (ORACLE_HOME = D:\Oracle\product\11.1.0\db_1)
    )
  )

listener1 =
  (DESCRIPTION_LIST =
    (DESCRIPTION =
      (ADDRESS = (PROTOCOL = TCP)(HOST = 127.0.0.1)(PORT = 1521))
    )
  )

# GLOBAL_DBNAME = ORCL1
这个参数表示数据库的服务名，用户可以自定义，客户端连接时需要用到，一共有哪些服务名可以通过 lsnrctl status 查看，其中 db_name.db_domain 这个服务名是数据库启动时自动添加的

# SID_NAME = ORCL
这个参数表示数据库的实例名，可以通过 select instance_name from v$instance 查看

# listener1 表示监听的名称，用户可以自定义