异常信息：
com.jcraft.jsch.JSchException: Session.connect: java.io.IOException: End of IO Stream Read
at com.jcraft.jsch.Session.connect(Session.java:565)
at com.jcraft.jsch.Session.connect(Session.java:183)
首先需要了解ssh协议的原理：https://www.cnblogs.com/zmlctt/p/3946860.html
然后开启JSch的日志打印功能，不然你是无法定位哪里错了，否则只能抓包
JSch只提供日志接口，如何打印日志，需要自己实现，代码如下
public class SftpLogger implements com.jcraft.jsch.Logger {
static Hashtable<Integer, String> name = new Hashtable<Integer, String>();
static {
name.put(new Integer(DEBUG), "DEBUG: ");
name.put(new Integer(INFO), "INFO: ");
name.put(new Integer(WARN), "WARN: ");
name.put(new Integer(ERROR), "ERROR: ");
name.put(new Integer(FATAL), "FATAL: ");
}
@Override
public boolean isEnabled(int level) {
return true;
}
@Override
public void log(int level, String message) {
//这里我们就用控制台红色字体输出
System.err.print(name.get(new Integer(level)));
System.err.println(message);
}
}
然后开启打印
public void login(String username, String password, String host, int port) {
JSch.setLogger(new SftpLogger()); //设置打印类
JSch jsch = new JSch();
Session session = null;
Channel channel = null;
try {
session = jsch.getSession(username,host,port);
session.setPassword(password);
session.setConfig("StrictHostKeyChecking", "no");
session.connect();
channel = session.openChannel("sftp");
channel.connect();
//do something
} catch (JSchException e) {
e.printStackTrace();
} finally {
if(channel != null){
channel.disconnect();
}
if(session != null){
session.disconnect();
}
}
}
开启打印日志后
Connecting to 198.23.12.158 port 8022
Connection established
Remote version string: SSH-2.0-OpenSSH_7.9
Local version string: SSH-2.0-JSCH-0.1.54
CheckCiphers: aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,3des-ctr,arcfour,arcfour128,arcfour256
aes256-ctr is not available.
aes192-ctr is not available.
aes256-cbc is not available.
aes192-cbc is not available.
CheckKexes: diffie-hellman-group14-sha1,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521
diffie-hellman-group14-sha1 is not available.
CheckSignatures: ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
SSH_MSG_KEXINIT sent
SSH_MSG_KEXINIT received
kex: server: diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256
kex: server: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
kex: server: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
kex: server: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
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
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
kex: server: none,zlib@openssh.com
kex: server: none,zlib@openssh.com
kex: server:
kex: server:
kex: client: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
kex: client: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
kex: client: aes128-ctr,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc
kex: client: aes128-ctr,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc
kex: client: hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha1-96,hmac-md5-96
kex: client: hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha1-96,hmac-md5-96
kex: client: none
kex: client: none
kex: client:
kex: client:
kex: server->client aes128-ctr hmac-sha1 none
kex: client->server aes128-ctr hmac-sha1 none
SSH_MSG_KEX_DH_GEX_REQUEST(1024<1024<1024) sent
expecting SSH_MSG_KEX_DH_GEX_GROUP
Disconnecting from 198.23.12.158 port 8022
com.jcraft.jsch.JSchException: Session.connect: java.io.IOException: End of IO Stream Read
at com.jcraft.jsch.Session.connect(Session.java:565)
at com.jcraft.jsch.Session.connect(Session.java:183)
上述日志中，你会发现有is not available的字样，说明客户端不支持这些算法。为什么不支持？因为jdk环境不支持！查看JSch源码，你会发现有些算法是需要jdk8的
config.put("diffie-hellman-group14-sha1",
"com.jcraft.jsch.DHG14"); // available since JDK8.
config.put("diffie-hellman-group-exchange-sha256",
"com.jcraft.jsch.DHGEX256"); // available since JDK1.4.2.
// On JDK8, 2048bits will be used.
config.put("ecdsa-sha2-nistp256", "com.jcraft.jsch.jce.SignatureECDSA256");
config.put("ecdsa-sha2-nistp384", "com.jcraft.jsch.jce.SignatureECDSA384");
config.put("ecdsa-sha2-nistp521", "com.jcraft.jsch.jce.SignatureECDSA521");
另外也可以从日志中kex: server服务端支持的算法，kex: client客户端支持的算法可以看出他们有能够匹配的算法，所以修改使用jdk8运行应用程序，问题解决！成功后的日志输出为
Connecting to 198.23.12.158 port 8022
Connection established
Remote version string: SSH-2.0-OpenSSH_7.9
Local version string: SSH-2.0-JSCH-0.1.54
CheckCiphers: aes256-ctr,aes192-ctr,aes128-ctr,aes256-cbc,aes192-cbc,aes128-cbc,3des-ctr,arcfour,arcfour128,arcfour256
CheckKexes: diffie-hellman-group14-sha1,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521
CheckSignatures: ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
SSH_MSG_KEXINIT sent
SSH_MSG_KEXINIT received
kex: server: diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256
kex: server: rsa-sha2-512,rsa-sha2-256,ssh-rsa,ecdsa-sha2-nistp256,ssh-ed25519
kex: server: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
kex: server: chacha20-poly1305@openssh.com,aes128-ctr,aes192-ctr,aes256-ctr,aes128-gcm@openssh.com,aes256-gcm@openssh.com
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
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
kex: server: none,zlib@openssh.com
kex: server: none,zlib@openssh.com
kex: server:
kex: server:
kex: client: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
kex: client: ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521
kex: client: aes128-ctr,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc,aes192-ctr,aes192-cbc,aes256-ctr,aes256-cbc
kex: client: aes128-ctr,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc,aes192-ctr,aes192-cbc,aes256-ctr,aes256-cbc
kex: client: hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha1-96,hmac-md5-96
kex: client: hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha1-96,hmac-md5-96
kex: client: none
kex: client: none
kex: client:
kex: client:
kex: server->client aes128-ctr hmac-sha1 none
kex: client->server aes128-ctr hmac-sha1 none
SSH_MSG_KEXDH_INIT sent
expecting SSH_MSG_KEXDH_REPLY
ssh_rsa_verify: signature true
Permanently added '198.23.12.158' (RSA) to the list of known hosts.
SSH_MSG_NEWKEYS sent
SSH_MSG_NEWKEYS received
SSH_MSG_SERVICE_REQUEST sent
SSH_MSG_SERVICE_ACCEPT received
Authentications that can continue: publickey,keyboard-interactive,password
Next authentication method: publickey
Authentications that can continue: keyboard-interactive,password
Next authentication method: keyboard-interactive
Authentications that can continue: password
Next authentication method: password
Authentication succeeded (password).
Disconnecting from 198.23.12.158 port 8022
我不想升级jdk8，是否有其他解决办法？通过看日志可以知道服务端支持的算法有：
kex: server: diffie-hellman-group1-sha1,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha1,diffie-hellman-group-exchange-sha256
客户端支持的算法有（也可以通过JSch源码查看）：
kex: client: ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1,diffie-hellman-group1-sha1
那么只需要在代码中这样设置，问题即可解决。把服务端优先支持且不需要jdk8支持的算法放在前面
//diffie-hellman-group1-sha1放前面
session.setConfig("kex", "diffie-hellman-group1-sha1,ecdh-sha2-nistp256,ecdh-sha2-nistp384,ecdh-sha2-nistp521,diffie-hellman-group14-sha1,diffie-hellman-group-exchange-sha256,diffie-hellman-group-exchange-sha1");
http://www.jcraft.com/jsch/
