Last days i stay face to face with a strange oracle problem.
I have defined database in tnsnames.ora. Oracle client is installed , client and client/bin have been added to PATH.

最后几天，我面对着一个奇怪的先知问题。我已经在tnsnames.ora中定义了数据库。Oracle客户端已安装，已将客户端和客户端/bin添加到PATH。

Ping works, tnsping works, I can connect to host by database port with telnet.

Ping工作，tnsping工作，我可以连接到主机的数据库端口与telnet。

When I try to run application that tries to connect to db I got

当我尝试运行尝试连接到数据库的应用程序时，我收到

ORA-12543: TNS:destination host unreachable

It is the same situation when I try to connect by sqlplus

当我尝试通过Sqlplus连接时也是如此

sqlplus username/password@TNSNAME

Situation occurred only on one workstation, it's mean in common it should works.

这种情况只发生在一台工作站上，这意味着它应该可以正常工作。

WS is windows 7 64 bit.

Database :

WS是64位Windows 7。数据库：

Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 - 64bit Production

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I was having the same problem, I resolved it by changing my password and removing "@" character. It worked for me.

我也遇到了同样的问题，我通过更改密码和删除“@”字符来解决它。这对我很管用。

@ is to tell SQL plus which connection identifier (service name/sid) we want to connect. In short, avoid using this character in password.

@是告诉SQL Plus我们要连接哪个连接标识符(服务名/sid)。简而言之，请避免在密码中使用此字符。

I also faced the same issue ORA-12543: TNS:destination host unreachable

我也遇到了同样的问题ORA-12543：TNS：目的地主机无法访问

i resolved it in this way

我是这样解决的

open sqlplus

打开sqlplus

connect

连接

enter user-name :system
enter password : HHHHH@2014

输入用户名：系统输入密码：hhhhh@2014

then the following error raised

则会引发以下错误

the problem is my password contains @ symbol

问题是我的密码包含@符号

resolved it by putting my password in "HHHHHH@2014"

通过在“HHHHHH@2014”中输入我的密码解决了这个问题

I too got ORA-12543 :TNS :destination host unreachable.
But for me the problem was in the password.

我也使ORA-12543：tns：目标主机无法访问。但对我来说，问题出在密码上。

Resolution : Need to remove "@" from the existing password as
@ defines connection identifier being used to connect in sqlPlus.

解决方法：需要从现有密码中删除“@”，因为@定义了在sqlPlus中用于连接的连接标识符。

To update the password , follow below steps :
Logon to window cmd then type "sqlplus /nolog"
then "connect / as sysdba" .
Once you are connected, change the SYS password to something without @:
"ALTER USER sys IDENTIFIED BY new_password;"

要更新密码，请执行以下步骤：登录到Windows cmd，然后键入“sqlplus/nolog”，然后输入“Connect/as sysdba”。连接后，将系统密码更改为不带@的密码：“ALTER USER SYS IDENTIFIED BY NEW_PASSWORD；”

(log in as sys dba)

(以sys dba身份登录)

sql>conn / as sysdba

(then alter the user)

(然后更改用户)

sql>alter user username identified by newuserName

sql>commit

(now again try to login with new user with the same password it will work)
click on 1 to see the screenshot -- ][1]

(现在再次尝试使用相同密码的新用户登录)单击1查看屏幕截图--][1]

Recently, I installed Oracle 11g for testing purpose and after completion of installation Database 11g Express Edition started on the browser with the system and Pravin@01 password it is connected successfully. After I tried using SQL Developer tool it was also working fine but while I tried to connect using SQL PLUS command line tool it suddenly gave me an error as,

最近，我安装了Oracle 11g用于测试目的，安装完成后，数据库11g Express Edition在浏览器上启动，系统和Pravin@01密码成功连接。在我尝试使用SQL Developer工具后，它也工作正常，但当我尝试使用SQL PLUS命令行工具连接时，它突然给了我一个错误，

---

ORA-12543: TNS:destination host unreachable

---

Then after research for an hour, I got a solution that Oracle treats @ character in the password as a `

然后经过一个小时的研究，我得到了一个解决方案，即Oracle将密码中的@字符视为`

service name or sid

so the solution for this problem is to remove @ character from the password using

因此，此问题的解决方案是使用以下命令从密码中删除@Character

ALTER USER system IDENTIFIED BY ' here is your new password which should contain character
and digits only try to eliminate special characters';

I think this post may be helpful for you.

我想这篇文章可能会对你有所帮助。

I have tested this in Windows 2016 environment with Oracle 18c 64-bit

我已经在Windows 2016环境中使用Oracle 18c 64位进行了测试

Use this following escape character sequence when attempting to logon with an "@" in the password.

尝试使用密码中的“@”登录时，请使用以下转义字符序列。

user: scott
password: scott@test

用户名：密码：密码：

sqlplus scott/\”scott@test\”@TEST_DB

In order avoid this annoyance, change password without an @ character using the following command once you have logged in to sqlplus.

为了避免这种麻烦，请在登录到SQLplus后使用以下命令更改不带@字符的密码。

alter user scott identified by "newpassword" 

Your current password must be containing "@" symbol and that's the problem.
So, just reset your password and dont use this symbol in your new password.

您当前的密码必须包含“@”符号，这就是问题所在。因此，只需重置您的密码，并且不要在您的新密码中使用此符号。

Adding to comments, if your current password contains "@" symbol then you need to reset password;
how to do step:
open sqlPlus
In enter username enter: / AS SYSDBA;
(connected to oracle)
reset in by:
ALTER USER sys IDENTIFIED BY new_password;

添加评论，如果您当前的密码包含“@”符号，则需要重置密码；操作步骤：在Enter Username Enter：/as SYSDBA；(连接到Oracle)Reset in：ALTER USER SYS BY NEW_PASSWORD中打开sqlPlus；

Use URL Encoding for special characters in your password instead of raw special characters while connecting through terminal.

在通过终端连接时，请对密码中的特殊字符使用URL编码，而不是原始的特殊字符。

Example :-

示例：-

if your connection string is :- sqlplus system/Password@12345@oracle as sysdba;

如果您的连接字符串是：-SQLPLUS SYSTEM/PASSWORD@12345@oracleas sysdba；

Then

然后

Acceptable connection url will be :- sqlplus system/Password%4012345@oracle as sysdba;. Here %40 is the URL Encoding for @, so replace all special characters with their respective URL Encoding and execute the connection command in terminal.

可接受的连接URL为：-SQLPLUS SYSTEM/PASSWORD%4012345@oracleas sysdba；。这里%40是@的URL编码，所以用它们各自的URL编码替换所有特殊字符，并在终端中执行连接命令。