JSchException：算法协商失败diffie-hellman-group14-sha1

Question

我知道有人问过几次，但我已经尝试了许多已经接受的解决方案。

我正在使用JSch创建一个简单的SSH隧道。而且我一直在日志中收到此错误以及与此相关的信息：

INFO: diffie-hellman-group14-sha1 is not available.

我已经将Java无限策略文件添加到了正确的文件夹中，并且将该算法添加到了sshd_config文件中的KexAlgorithms部分。以下是完整的日志明细。

INFO: Connecting to xx.xx.xxx.xxx port 22
INFO: Connection established
INFO: Remote version string: SSH-2.0-OpenSSH_6.8
INFO: Local version string: SSH-2.0-JSCH-0.1.50
INFO: CheckCiphers: aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-     cbc,aes128-cbc,3des-ctr,arcfour,arcfour128,arcfour256
INFO: CheckKexes: diffie-hellman-group14-sha1
INFO: diffie-hellman-group14-sha1 is not available.
INFO: SSH_MSG_KEXINIT sent
INFO: SSH_MSG_KEXINIT received
INFO: kex: server: curve25519-sha256@libssh.org,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group14-sha1
INFO: kex: server: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ssh-ed25519
INFO: kex: server: aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com
INFO: kex: server: aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com,chacha20-poly1305@openssh.com
INFO: kex: server: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
INFO: kex: server: umac-64-etm@openssh.com,umac-128-etm@openssh.com,hmac-sha2-256-etm@openssh.com,hmac-sha2-512-etm@openssh.com,hmac-sha1-etm@openssh.com,umac-64@openssh.com,umac-128@openssh.com,hmac-sha2-256,hmac-sha2-512,hmac-sha1
INFO: kex: server: none,zlib@openssh.com
INFO: kex: server: none,zlib@openssh.com
INFO: kex: server: 
INFO: kex: server: 
INFO: kex: client: diffie-hellman-group1-sha1,diffie-hellman-group-exchange-sha1
INFO: kex: client: ssh-rsa,ssh-dss
INFO: kex: client: aes256-cbc
INFO: kex: client: aes128-ctr,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc,aes192-cbc,aes256-cbc
INFO: kex: client: hmac-sha2-256
INFO: kex: client: hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha1-96,hmac-md5-96
INFO: kex: client: none
INFO: kex: client: none
INFO: kex: client: 
INFO: kex: client: 
INFO: Disconnecting from xx.xx.xxx.xxx port 22
com.jcraft.jsch.JSchException: Algorithm negotiation fail

Answer 1

您的客户端和服务器不共享通用的KEX算法：

信息：kex：服务器：curve25519-sha256 @ libssh.org，ecdh-sha2-nistp256，ecdh-sha2-nistp384，ecdh-sha2-nistp521，diffie-hellman-group-exchange-sha256，diffie-hellman-group14-sha1

信息：kex：客户：diffie-hellman-group1-sha1，diffie-hellman-group-exchange-sha1

如您所见，在另一方的列表中找不到任何一方支持的算法。您可以通过以下两种方式之一将对其他KEX算法的支持添加到客户端：

1. 将JSch升级到最新版本（0.1.52），以自动启用对sha256的支持。

2. 如果您坚持使用0.1.51，则可以以编程方式启用sha256：

   JSch shell = new JSch();
   Properties config = new Properties();
   config.put("kex", "diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256");
   config.put("StrictHostKeyChecking", "no");
   

   然后创建您的会话并使用以下命令设置配置：

   Session session = ...
   session.setConfig(config);