groupadd sftp

useradd -g sftp mysftp

passwd mysftp

mkdir /app/data

usermod -d /app/data mysftp

vim /etc/ssh/sshd_config

#注释掉下面一行，改用自定义的
#Subsystem      sftp    /usr/libexec/openssh/sftp-server
Subsystem sftp internal-sftp #这行指定使用sftp服务使用系统自带的internal-sftp
Match Group sftp #这行用来匹配用户组
ChrootDirectory /app/data  #用chroot将用户的根目录指定到/app/data ，这样用户就只能在/app/data 下活动
AllowTcpForwarding no
ForceCommand internal-sftp #指定sftp命令

mkdir /app/data/upload
chown -R mysftp:sftp /app/data/upload/
mkdir /app/data/download
chown -R mysftp:sftp /app/data/download/

service sshd restart

public static void main(String[] args) {
    JSch jSch = new JSch();
    Session session = null;
    Channel channel = null;
    OutputStream outputStream = null;
    InputStream inputStream = null;
    ChannelSftp channelSftp;
    String xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" +
            "<Message>\n" +
            "    <Data>我是一个测试文件</Data>\n" +
            "</Message>\n";
    try {
        session = jSch.getSession("mysftp", "192.168.141.100", 22);
        session.setPassword("xxxxxx");
        Properties properties = new Properties();
        properties.setProperty("StrictHostKeyChecking", "no");
        session.setConfig(properties);
        session.connect(30000);
        channel = session.openChannel("sftp");
        channel.connect(30000);
        channelSftp = (ChannelSftp) channel;
        channelSftp.cd("/upload");
        outputStream = channelSftp.put("test.xml");
        inputStream = new ByteArrayInputStream(xml.getBytes(StandardCharsets.UTF_8));
        byte[] b = new byte[1024];
        int n;
        while ((n = inputStream.read(b)) != -1) {
            outputStream.write(b, 0, n);
        }
        outputStream.flush();
    } catch (Exception e) {
        e.printStackTrace();
    } finally {
        if (null != outputStream) {
            try {
                outputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (null != inputStream) {
            try {
                inputStream.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        if (null != session) {
            session.disconnect();
        }
        if (null != channel && channel.isConnected()) {
            channel.disconnect();
        }
    }
}

[root@root /]# sftp mysftp@127.0.0.1
mysftp@127.0.0.1's password: 
Connected to 127.0.0.1.
sftp> pwd
Remote working directory: /
sftp> 

netstat -anp | grep :22 | grep ESTABLISHED | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n