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How to Solve Mule SFTP Connector Algorithm Negotiation Fail Exception

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How to Solve Mule SFTP Connector Algorithm Negotiation Fail Exception

This quick tutorial will show you how to resolve issues with the Mule SFTP connector connecting to remote file locations.

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This article is the resolution of the Mule SFTP connector when connecting to remote file locations.

The configurations details are below:

<?xml version="1.0" encoding="UTF-8"?>
<mule xmlns:sftp="http://www.mulesoft.org/schema/mule/sftp" xmlns="http://www.mulesoft.org/schema/mule/core" xmlns:doc="http://www.mulesoft.org/schema/mule/documentation"
       xmlns:spring="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-current.xsd
http://www.mulesoft.org/schema/mule/core http://www.mulesoft.org/schema/mule/core/current/mule.xsd
http://www.mulesoft.org/schema/mule/sftp http://www.mulesoft.org/schema/mule/sftp/current/mule-sftp.xsd">
       <sftp:connector name="SFTP" validateConnections="true" doc:name="SFTP" />
       <flow name="sftpflow">
             <sftp:inbound-endpoint connector-ref="SFTP" host="host_ip" port="22" path="File Loactions " user="USERNAME" password="PASSWORD"
                    responseTimeout="10000" doc:name="SFTP" >
            <reconnect count="3"/>
             <logger message="Able to read file :- #[payload]" level="INFO" doc:name="Logger" />

The exception will be:

com.jcraft.jsch.JSchException: Algorithm negotiation fail
       at com.jcraft.jsch.Session.receive_kexinit(Session.java:583) ~[jsch-0.1.51.jar:?]

The SFTP connector for Mule has the in-built support jsch-0.1.51.jar. So, while connecting to secure file locations through the SFTP connector, the com.jcraft.jsch.JSchException: Algorithm negotiation fail exception is thrown.

In the JSch.class for jsch-0.1.51.jar, for the KEY -->"kex," it does not have the value "diffie-hellman-group-exchange-sha256" for connecting to the remote location securely. The sha256 exchange pattern is required, which is there in the jsch-0.1.54.jar file. But for 3.6.2/3.7.1 and 3.8.1 runtime versions, the in-built third party jsch-0.1.51.jar has been used.

The Workaround

 Override the KEY "kex" and add the value diffie-hellman-group-exchange-sha256.

The following block should be added in the Static block:

configuration.put("kex", "diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256");


public class JSchKeyConfig {
 static {
  Properties configuration = new Properties();
  configuration.put("kex", "diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256");

Inject the JSchKeyConfig through Spring beans. 

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mule 3.7 ,java ,mule ,tutorial ,integration

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