Several wiring layouts are in use, because the null modem connection is not covered by a standard.

有多种连接方式可供选择，因为标准中并未涵盖零调制解调器连接。

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The system level error includes syntactical error, null pointer exception, web service timeout, database connection timeout, and so on.

系统级错误包括语法错误、空指针异常、web服务超时、数据库连接超时等。

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Use any (non-null) value for user ID and password, and click the Test Connection button.

使用任意（非空）值作为用户 ID 和密码，并单击 Test Connection 按钮。

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Ideally, that machine would have no network connection (as it would be a prime break-in target), and be reported to via null-modem serial cable only.

CNN: Analysis: Linux security