Home / Questions / 219107
Accepted
akko
Asked: 2020-12-04 11:17:30 +0800 CST 2020-12-04 11:17:30 +0800 CST

How to refer to a server on the local network in linux?

  • 772

I have the following problem, I have an express project that uses the package mssqlto connect to a SQL Server database. To make the connection I have to specify the data in an object.

produccion = {
  user: 'xxx',
  password: 'xxx',
  server: 'nombre\\nombre',
  database: 'xxx'
};

In the case of servercontains a \\. Although I really don't know why.

I am developing the project on the local network with a Windows machine, I have no problem connecting to the server. Now when I pass it to a Debian server that is also on the local network the connection cannot be established.

I have tried to replace the nombre\\nombrewith the ip, but it doesn't work either on my windows machine or on the debian server.

This is the error it sends me:

{ ConnectionError: Failed to lookup instance on miServidor - getaddrinfo ENOTFOUND miServidor    at Connection.tedious.once.err (/var/www/html/node_modules/mssql/lib/tedious.js:239:17)    at Object.onceWrapper (events.js:273:13)    at Connection.emit (events.js:182:13)    at /var/www/html/node_modules/tedious/lib/connection.js:848:20    at /var/www/html/node_modules/tedious/lib/instance-lookup.js:83:15    at GetAddrInfoReqWrap.callback (/var/www/html/node_modules/tedious/lib/sender.js:58:18)    at GetAddrInfoReqWrap.onlookupall [as oncomplete] (dns.js:70:17)  code: 'EINSTLOOKUP',  originalError:   { ConnectionError: Failed to lookup instance on miServidor - getaddrinfo ENOTFOUND miServidor       at ConnectionError (/var/www/html/node_modules/tedious/lib/errors.js:12:12)       at /var/www/html/node_modules/tedious/lib/connection.js:848:36       at /var/www/html/node_modules/tedious/lib/instance-lookup.js:83:15       at GetAddrInfoReqWrap.callback (/var/www/html/node_modules/tedious/lib/sender.js:58:18)       at GetAddrInfoReqWrap.onlookupall [as oncomplete] (dns.js:70:17)     message:      'Failed to lookup instance on miServidor - getaddrinfo ENOTFOUND miServidor',
     code: 'EINSTLOOKUP' },
  name: 'ConnectionError' }

The documentation mssqlis not very clear about the EINSTLOOKUP.

EINSTLOOKUP (ConnectionError) - Instance lookup failed.
javascript

1 Answers

  1. Best Answer

    You cannot substitute nombre\nombrefor an IP, since they are not equivalent. I am going to explain to you what the SQL Server client supports in that connection parameter and I think after that you will be able to do it yourself.

    When you are going to connect to a database, there is a parameter commonly known as server name , server name or simply server , which tells the engine the qualified name of the SQL Server instance to connect to.

    In other words, it is not the computer to which it connects, but the instance , which will always reside inside a computer and can be the only instance or the default instance (more on that later).

    Let's start by defining the parts a can eventually be composed of:

    • host is the computer to which we want to communicate, it can be
      • A computer name on a Windows (NetBios) network, for example, MiPCorJuan-Laptop
      • A hostname (local or remote) in the DNS structure, for example midominio.com, basededatos.midominio.com, etc.
      • An IP accessible from the network (private or public), such as 127.0.0.1, 192.168.0.41, 190.191.192.193, etc.
      • The special name (local), which always resolves to the team itself.
    • instanceName is the name given to the instance within the database server host . Remember that a single computer can have one or several instances of the database server, each with its own configuration and even running different versions of SQL Server .
    • TCPPort is the TCP port number that a particular instance has been configured to listen on over the network.

    With this in mind, the server name string can take 3 forms:

    1. host\instanceName : examples: ServidorBD\SQLExpress, db.miempresa.com\MainERP, 10.14.17.11\Pruebas, etc.
    2. host, portTCP : examples: ServidorBD,1433, db.miempresa.com,61254,10.14.17.11,18141
    3. host Connects to the default (unnamed) instance on a computer, through port 1433, which is the SQL Server standard.

    This is the same whether the server is Windows or Linux .

    To diagnose the problem, what you should verify, from the computer where you are trying to establish the connection, is that:

    • The server name can be resolved without problems. You can easily test it, for example, making a pingwith the name of the server, taking advantage of the fact that this command looksup the name, translates it to an IP address and finally tries to ping . A test on Windows, when it can't resolve the name, returns something like:

      C:\Users\juan>ping prueba
La solicitud de ping no pudo encontrar el host prueba. Compruebe el nombre y
vuelva a intentarlo.

      In linux it is something similar

    • That you can connect to the SQL server port , either with telnet, with a SQL Server client or with any other program that can establish a TCP connection, for example.

      C:\Users\juan>telnet MiServidor 1433
    • 2