Java FTPS disabling Certificate Check , FOR FIX FTP SSL certificate expired exception

Published at

3/26/2024

Categories

2 categories in total

1)the encryption of the FTPS server will be either TLS explicit encryption or TLS explicit encryption.Use the constructor arg for FTPS accordingly. like

FTPSClient ftpClient = new FTPSClient(false);

2)if your FTPS server security certificate has expired, disable the check from client by

ftpClient.setTrustManager(new X509TrustManager() {
    @Override
    public X509Certificate[] getAcceptedIssuers() {
        return null;
    }

    @Override
    public void checkClientTrusted(X509Certificate[] certs, String authType) {
    }

    @Override
    public void checkServerTrusted(X509Certificate[] certs, String authType) {
    }
});

3)enable file transfer between server and client using this method

ftpClient.enterLocalPassiveMode();

4)use the right port number. Usually for explicit encryption it is 21 and for implicit it is 990

The above four are the common configs required to establish a connection. The end snippet looks something like this


FTPSClient ftpClient = new FTPSClient(false);
        ftpClient.setTrustManager(new X509TrustManager() {
            @Override
            public X509Certificate[] getAcceptedIssuers() {
                return null;
            }

            @Override
            public void checkClientTrusted(X509Certificate[] certs, String authType) {
            }

            @Override
            public void checkServerTrusted(X509Certificate[] certs, String authType) {
            }
        });
        ftpClient.connect("ftps.mydomain.com",21);
        boolean res = ftpClient.login("username", "password");
        if(!res) throw new Exception("unable to connect to ftps");
        int reply=ftpClient.getReplyCode();
        if(FTPReply.isPositiveCompletion(reply)){
            ftpClient.enterLocalPassiveMode();
            FTPFile[] ftpFiles = ftpClient.listFiles("/folder/subfolder");
            System.out.println("complete "+reply+" "+ftpFiles.length);
            for(FTPFile x: ftpFiles){
                System.out.println(x.getName());
            }
            ftpClient.retrieveFile("/folder/subfolder/file.tsv",new FileOutputStream(new File("C:\\Users\\myname\\Desktop\\out.csv")));
        }else{
            throw new RuntimeException("unable to get valid reply from ftp server. Reply code is "+reply);
        }

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Java FTPS disabling Certificate Check , FOR FIX FTP SSL certificate expired exception