ganymed-ssh2连接openssh 8.2
ganymed-ssh2连接openssh 8.2
存在的问题
ganymed-ssh2是一个ssh-2协议实现,因为该项目比较老旧,当sshd服务使用较新的openssh时,一般情况下是无法正常建立ssh连接的。
访问sshd的代码,如下所示:
public class Main {public static void main(String[] args) throws IOException {String ipAddress = "127.0.0.1";ch.ethz.ssh2.Connection conn = new ch.ethz.ssh2.Connection(ipAddress,22);conn.connect();boolean isAuthenticated = conn.authenticateWithPassword("username", "password");if (isAuthenticated == false)throw new IOException("Authentication failed.");}
}
当使用如下代码访问sshd时,系统会报如下异常:
解决方法
找到报错代码
下载ganymed-ssh2源码,源码地址为https://www.ganymed.ethz.ch/ssh2/。
找到ch.ethz.ssh2.transport.KexManager文件,搜索异常关键字"Cannot negotiate, proposals do not match."。代码如下所示:
kxs.np = mergeKexParameters(kxs.localKEX.getKexParameters(), kxs.remoteKEX.getKexParameters());if (kxs.np == null)throw new IOException("Cannot negotiate, proposals do not match.");
从中可知,mergeKexParameters方法返回的kxs.np为空,导致报上述异常。进入mergeKexParameters方法,发现异常原因是因为getFirstMatch方法返回NegotiateException。
打印客户端和服务端协商的算法过程
private String getFirstMatch(String[] client, String[] server) throws NegotiateException{if (client == null || server == null)throw new IllegalArgumentException();if (client.length == 0)return null;log.log(20, "------------------------------");for (int i = 0; i < client.length; i++){log.log(20, "client-->" + client[i]);for (int j = 0; j < server.length; j++){log.log(20, "server-->" + server[i]);if (client[i].equals(server[j]))return client[i];}}log.log(20, "------------------------------");throw new NegotiateException();}
1750672202863 : ch.ethz.ssh2.transport.TransportConnection: Sent SSH_MSG_KEXINIT 478 bytes payload
1750672202864 : ch.ethz.ssh2.transport.TransportConnection: Received SSH_MSG_KEXINIT 929 bytes payload
1750672202868 : ch.ethz.ssh2.transport.KexManager: ------------------------------
1750672202868 : ch.ethz.ssh2.transport.KexManager: client-->diffie-hellman-group-exchange-sha1
1750672202868 : ch.ethz.ssh2.transport.KexManager: server-->curve25519-sha256
1750672202868 : ch.ethz.ssh2.transport.KexManager: server-->curve25519-sha256
1750672202868 : ch.ethz.ssh2.transport.KexManager: server-->curve25519-sha256
1750672202868 : ch.ethz.ssh2.transport.KexManager: server-->curve25519-sha256
1750672202868 : ch.ethz.ssh2.transport.KexManager: server-->curve25519-sha256
1750672202868 : ch.ethz.ssh2.transport.KexManager: kex_algo=diffie-hellman-group-exchange-sha1
1750672202868 : ch.ethz.ssh2.transport.KexManager: ------------------------------
1750672202868 : ch.ethz.ssh2.transport.KexManager: client-->ssh-rsa
1750672202868 : ch.ethz.ssh2.transport.KexManager: server-->rsa-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->rsa-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->rsa-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: server_host_key_algo=ssh-rsa
1750672202869 : ch.ethz.ssh2.transport.KexManager: ------------------------------
1750672202869 : ch.ethz.ssh2.transport.KexManager: client-->aes256-ctr
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: ------------------------------
1750672202869 : ch.ethz.ssh2.transport.KexManager: client-->aes256-ctr
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->3des-cbc
1750672202869 : ch.ethz.ssh2.transport.KexManager: enc_algo_client_to_server=aes256-ctr
1750672202869 : ch.ethz.ssh2.transport.KexManager: enc_algo_server_to_client=aes256-ctr
1750672202869 : ch.ethz.ssh2.transport.KexManager: ------------------------------
1750672202869 : ch.ethz.ssh2.transport.KexManager: client-->hmac-sha1-96
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512
1750672202869 : ch.ethz.ssh2.transport.KexManager: client-->hmac-sha1
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512-etm@openssh.com
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512-etm@openssh.com
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512-etm@openssh.com
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-512-etm@openssh.com
1750672202869 : ch.ethz.ssh2.transport.KexManager: client-->hmac-md5-96
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256
1750672202869 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256
1750672202870 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256
1750672202870 : ch.ethz.ssh2.transport.KexManager: client-->hmac-md5
1750672202870 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256-etm@openssh.com
1750672202870 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256-etm@openssh.com
1750672202870 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256-etm@openssh.com
1750672202870 : ch.ethz.ssh2.transport.KexManager: server-->hmac-sha2-256-etm@openssh.com
1750672202870 : ch.ethz.ssh2.transport.KexManager: ------------------------------
1750672202870 : ch.ethz.ssh2.transport.TransportManager: Receive thread: error in receiveLoop: Cannot negotiate, proposals do not match.
1750672202870 : ch.ethz.ssh2.transport.TransportManager: Receive thread: back from receiveLoop
从日志可知,客户端支持的算法有:hmac-sha1-96,hmac-sha1,hmac-md5-96,hmac-md5四种;服务端支持的算法有:hmac-sha2-512,hmac-sha2-512-etm@openssh.com,hmac-sha2-256,hmac-sha2-256-etm@openssh.com四种。客户端和服务端没有共同的算法。
查看服务器/etc/ssh/sshd_config文件,可知,hmac算法配置在MACs项中。 修改sshd_config,新增算法hmac-sha1-96,hmac-sha1,hmac-md5-96,hmac-md5,然后重启sshd服务。
测试ssh连接
略
idea编译ganymed-ssh2
解压下载的源码
unzip ganymed-ssh2-build210.zip -d ganymed
添加pom.xml配置
ganymed-ssh2是一个普通的java工程,不方便编译和打包测试,将其转换为maven项目。
<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0"xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd"><modelVersion>4.0.0</modelVersion><groupId>ch.ethz.ssh2</groupId><artifactId>test-ganymed</artifactId><version>1.0</version><properties><maven.compiler.source>8</maven.compiler.source><maven.compiler.target>8</maven.compiler.target><project.build.sourceEncoding>UTF-8</project.build.sourceEncoding></properties><build><plugins><plugin><groupId>org.apache.maven.plugins</groupId><artifactId>maven-shade-plugin</artifactId><version>3.2.4</version><executions><execution><phase>package</phase><goals><goal>shade</goal></goals><configuration><transformers><transformerimplementation="org.apache.maven.plugins.shade.resource.ManifestResourceTransformer"><mainClass>ch.ethz.ssh2.Main</mainClass></transformer></transformers></configuration></execution></executions></plugin></plugins></build>
</project>
导入idea
在idea中鼠标右键选中pom.xml, 点击"Add as Maven Project"。此时,ganymed项目可以在idea下,通过maven插件进行编译和打包。