最近接触jsch这个包，发现在默认情况下，jsch登录ssh的时候，协商的加密算法和mac算法都不是最高优先级的，这个时候需要手动配置一下算法列表，将强度高的调整在算法列表的前面，这样ssh链接的时候，如果双方都，就会协商成高优先级算法。代码参数jsch的示例，只是添加了一个配置文件，通过wireshark抓包来观测配置前后的变化。

测试结果：

默认不配置：

配置算法列表：

代码：

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importjava.io.InputStream;

importjava.util.Properties;

importcom.jcraft.jsch.*;

publicclassjschSample{

publicstaticvoidmain(String[]args){

// TODO Auto-generated method stub

Propertiesp=newProperties();

p.setProperty("cipher.s2c","aes256-ctr,aes192-ctr,aes128-ctr");

p.setProperty("cipher.c2s","aes256-ctr,aes192-ctr,aes128-ctr");

p.setProperty("mac.s2c","hmac-sha2,hmac-sha1");

p.setProperty("mac.c2s","hmac-sha2,hmac-sha1");

p.setProperty("kex","ecdh-sha2-nistp256");

p.setProperty("StrictHostKeyChecking","no");

try{

JSchjsch=newJSch();

Sessionsession=jsch.getSession("pi","192.168.1.7",22);

session.setConfig(p);

session.setPassword("raspberry");

session.connect();

Channelchannel=session.openChannel("exec");

((ChannelExec)channel).setCommand("pwd");

channel.setInputStream(null);

InputStreamin=channel.getInputStream();

channel.connect();

byte[]tmp=newbyte[1024];

while(true){

while(in.available()>0){

inti=in.read(tmp,0,1024);

if(i<0)break;

System.out.print(newString(tmp,0,i));

}

if(channel.isClosed()){

if(in.available()>0)continue;

System.out.println("exit-status: "+channel.getExitStatus());

break;

}

try{Thread.sleep(1000);}catch(Exceptionee){}

}

channel.disconnect();

session.disconnect();

}

catch(Exceptione)

{

System.out.println(e);

}

}

}

捕获到的jsch0.1.55版本消息算法列表如下(encryption_algorithms/mac_algorithms算法s2c和c2s是一样的)：

kex_algorithms string:

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

server_host_key_algorithms string:

ssh-rsa,ssh-dss,ecdsa-sha2-nistp256,ecdsa-sha2-nistp384,ecdsa-sha2-nistp521

encryption_algorithms_client_to_server string:

aes128-ctr,aes128-cbc,3des-ctr,3des-cbc,blowfish-cbc,aes192-ctr,aes192-cbc,aes256-ctr,aes256-cbc

mac_algorithms_client_to_server string:

hmac-md5,hmac-sha1,hmac-sha2-256,hmac-sha1-96,hmac-md5-96

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