20
votes

I'm trying use an SSL client/server example from:http://simplestcodings.blogspot.com.br/2010/08/secure-server-client-using-openssl-in-c.html to create a secure connection using SSLv3. I made some changes for request the certificate on server-side, the comunication works fine and is understood in both sides. Thus, my problem is that when the client connects to server, the protocol communication SSLv3 is not working, I verified using the wirkeshark and in the protocol field just shows TCP, or IPA(RSL Malformed Packet) somebody can help me? Thanks!

I've created my certificates following the tutorial https://help.ubuntu.com/community/OpenSSL.

Here is my client code:

//SSL-Client.c
#include <stdio.h>
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <sys/socket.h>
#include <resolv.h>
#include <netdb.h>
#include <openssl/ssl.h>
#include <openssl/err.h>

#define FAIL    -1

    //Added the LoadCertificates how in the server-side makes.    
void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile)
{
 /* set the local certificate from CertFile */
    if ( SSL_CTX_use_certificate_file(ctx, CertFile, SSL_FILETYPE_PEM) <= 0 )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* set the private key from KeyFile (may be the same as CertFile) */
    if ( SSL_CTX_use_PrivateKey_file(ctx, KeyFile, SSL_FILETYPE_PEM) <= 0 )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* verify private key */
    if ( !SSL_CTX_check_private_key(ctx) )
    {
        fprintf(stderr, "Private key does not match the public certificate\n");
        abort();
    }
}

int OpenConnection(const char *hostname, int port)
{   int sd;
    struct hostent *host;
    struct sockaddr_in addr;

    if ( (host = gethostbyname(hostname)) == NULL )
    {
        perror(hostname);
        abort();
    }
    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = *(long*)(host->h_addr);
    if ( connect(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
    {
        close(sd);
        perror(hostname);
        abort();
    }
    return sd;
}

SSL_CTX* InitCTX(void)
{   SSL_METHOD *method;
    SSL_CTX *ctx;

    OpenSSL_add_all_algorithms();  /* Load cryptos, et.al. */
    SSL_load_error_strings();   /* Bring in and register error messages */
    method = SSLv3_client_method();  /* Create new client-method instance */
    ctx = SSL_CTX_new(method);   /* Create new context */
    if ( ctx == NULL )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}

void ShowCerts(SSL* ssl)
{   X509 *cert;
    char *line;

    cert = SSL_get_peer_certificate(ssl); /* get the server's certificate */
    if ( cert != NULL )
    {
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);       /* free the malloc'ed string */
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);       /* free the malloc'ed string */
        X509_free(cert);     /* free the malloc'ed certificate copy */
    }
    else
        printf("No certificates.\n");
}

int main()
{   SSL_CTX *ctx;
    int server;
    SSL *ssl;
    char buf[1024];
    int bytes;
    char hostname[]="127.0.0.1";
    char portnum[]="5000";
    char CertFile[] = "/home/myCA/cacert.pem";
    char KeyFile[] = "/home/myCA/private/cakey.pem";

    SSL_library_init();

    ctx = InitCTX();
    LoadCertificates(ctx, CertFile, KeyFile);
    server = OpenConnection(hostname, atoi(portnum));
    ssl = SSL_new(ctx);      /* create new SSL connection state */
    SSL_set_fd(ssl, server);    /* attach the socket descriptor */
    if ( SSL_connect(ssl) == FAIL )   /* perform the connection */
        ERR_print_errors_fp(stderr);
    else
    {   char *msg = "Hello???";

        printf("Connected with %s encryption\n", SSL_get_cipher(ssl));
        ShowCerts(ssl);        /* get any certs */
        SSL_write(ssl, msg, strlen(msg));   /* encrypt & send message */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get reply & decrypt */
        buf[bytes] = 0;
        printf("Received: \"%s\"\n", buf);
        SSL_free(ssl);        /* release connection state */
    }
    close(server);         /* close socket */
    SSL_CTX_free(ctx);        /* release context */
    return 0;
}

And the server:

//SSL-Server.c
#include <errno.h>
#include <unistd.h>
#include <malloc.h>
#include <string.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <netinet/in.h>
#include <resolv.h>
#include "openssl/ssl.h"
#include "openssl/err.h"

#define FAIL    -1

int OpenListener(int port)
{   int sd;
    struct sockaddr_in addr;

    sd = socket(PF_INET, SOCK_STREAM, 0);
    bzero(&addr, sizeof(addr));
    addr.sin_family = AF_INET;
    addr.sin_port = htons(port);
    addr.sin_addr.s_addr = INADDR_ANY;
    if ( bind(sd, (struct sockaddr*)&addr, sizeof(addr)) != 0 )
    {
        perror("can't bind port");
        abort();
    }
    if ( listen(sd, 10) != 0 )
    {
        perror("Can't configure listening port");
        abort();
    }
    return sd;
}

SSL_CTX* InitServerCTX(void)
{   SSL_METHOD *method;
    SSL_CTX *ctx;

    OpenSSL_add_all_algorithms();  /* load & register all cryptos, etc. */
    SSL_load_error_strings();   /* load all error messages */
    method = SSLv3_server_method();  /* create new server-method instance */
    ctx = SSL_CTX_new(method);   /* create new context from method */
    if ( ctx == NULL )
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    return ctx;
}

void LoadCertificates(SSL_CTX* ctx, char* CertFile, char* KeyFile)
{
    //New lines 
    if (SSL_CTX_load_verify_locations(ctx, CertFile, KeyFile) != 1)
        ERR_print_errors_fp(stderr);

    if (SSL_CTX_set_default_verify_paths(ctx) != 1)
        ERR_print_errors_fp(stderr);
    //End new lines

    /* set the local certificate from CertFile */
    if (SSL_CTX_use_certificate_file(ctx, CertFile, SSL_FILETYPE_PEM) <= 0)
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* set the private key from KeyFile (may be the same as CertFile) */
    if (SSL_CTX_use_PrivateKey_file(ctx, KeyFile, SSL_FILETYPE_PEM) <= 0)
    {
        ERR_print_errors_fp(stderr);
        abort();
    }
    /* verify private key */
    if (!SSL_CTX_check_private_key(ctx))
    {
        fprintf(stderr, "Private key does not match the public certificate\n");
        abort();
    }

    //New lines - Force the client-side have a certificate
    SSL_CTX_set_verify(ctx, SSL_VERIFY_PEER | SSL_VERIFY_FAIL_IF_NO_PEER_CERT, NULL);
    SSL_CTX_set_verify_depth(ctx, 4);
    //End new lines
}

void ShowCerts(SSL* ssl)
{   X509 *cert;
    char *line;

    cert = SSL_get_peer_certificate(ssl); /* Get certificates (if available) */
    if ( cert != NULL )
    {
        printf("Server certificates:\n");
        line = X509_NAME_oneline(X509_get_subject_name(cert), 0, 0);
        printf("Subject: %s\n", line);
        free(line);
        line = X509_NAME_oneline(X509_get_issuer_name(cert), 0, 0);
        printf("Issuer: %s\n", line);
        free(line);
        X509_free(cert);
    }
    else
        printf("No certificates.\n");
}

void Servlet(SSL* ssl) /* Serve the connection -- threadable */
{   char buf[1024];
    char reply[1024];
    int sd, bytes;
    const char* HTMLecho="<html><body><pre>%s</pre></body></html>\n\n";

    if ( SSL_accept(ssl) == FAIL )     /* do SSL-protocol accept */
        ERR_print_errors_fp(stderr);
    else
    {
        ShowCerts(ssl);        /* get any certificates */
        bytes = SSL_read(ssl, buf, sizeof(buf)); /* get request */
        if ( bytes > 0 )
        {
            buf[bytes] = 0;
            printf("Client msg: \"%s\"\n", buf);
            sprintf(reply, HTMLecho, buf);   /* construct reply */
            SSL_write(ssl, reply, strlen(reply)); /* send reply */
        }
        else
            ERR_print_errors_fp(stderr);
    }
    sd = SSL_get_fd(ssl);       /* get socket connection */
    SSL_free(ssl);         /* release SSL state */
    close(sd);          /* close connection */
}

int main()
{   SSL_CTX *ctx;
    int server;
    char portnum[]="5000";

        char CertFile[] = "/home/myCA/mycert.pem";
        char KeyFile[] = "/home/myCA/mycert.pem";

    SSL_library_init();

    ctx = InitServerCTX();        /* initialize SSL */
    LoadCertificates(ctx, CertFile, KeyFile); /* load certs */
    server = OpenListener(atoi(portnum));    /* create server socket */
    while (1)
    {   struct sockaddr_in addr;
        socklen_t len = sizeof(addr);
        SSL *ssl;

        int client = accept(server, (struct sockaddr*)&addr, &len);  /* accept connection as usual */
        printf("Connection: %s:%d\n",inet_ntoa(addr.sin_addr), ntohs(addr.sin_port));
        ssl = SSL_new(ctx);              /* get new SSL state with context */
        SSL_set_fd(ssl, client);      /* set connection socket to SSL state */
        Servlet(ssl);         /* service connection */
    }
    close(server);          /* close server socket */
    SSL_CTX_free(ctx);         /* release context */
}
3
You need to tell Wireshark what protocol is running on what port because you are using a non-standard port. That will allow the correct dissector to run. See Control Protocol dissection in the Wireshark docs.jww
it takes default cipher suite AES256-SHA ? for TLS 1.2 , in my program it takes AES256-GCM-SHA384 ? how this possible?lucifer

3 Answers

9
votes

With the above server and client programs, I was getting the following error:

140671281543104:error:140890B2:SSL routines:SSL3_GET_CLIENT_CERTIFICATE:no certificate returned:s3_srvr.c:3292:

I had generated self-signed certificates using the procedure mentioned in https://help.ubuntu.com/community/OpenSSL.

After juggling with the error for one day, i found that the error was because the self-generated CA was not in the trust chain of the machine I was using.

To add the CA to the trust chain in RHEL-7, one can follow the below procedure:

        To add a certificate in the simple PEM or DER file formats to the
        list of CAs trusted on the system:

        Copy it to the
                /etc/pki/ca-trust/source/anchors/
        subdirectory, and run the
                update-ca-trust
        command.

        If your certificate is in the extended BEGIN TRUSTED file format,
        then place it into the main source/ directory instead.

I think the above procedure can be followed for fedora too. If this does not work, it might be useful to explore the commands like "update-ca-certificates". Hope this will be useful to someone.

6
votes

you must to modify your code (server side): your code:

int main()
{   SSL_CTX *ctx;
    int server;
    **char portnum[]="5000";**

        char CertFile[] = "/home/myCA/mycert.pem";
        char KeyFile[] = "/home/myCA/mycert.pem";

    SSL_library_init();

    **portnum = strings[1];**

instead you should use this:

int main(int argc, char **argv)
{   SSL_CTX *ctx;
    int server;
    //char portnum[]="5000"; ---> You can pass it as an argument

        char CertFile[] = "/home/myCA/mycert.pem";
        char KeyFile[] = "/home/myCA/mycert.pem";

    SSL_library_init();

    //portnum = strings[1]; 
    portnum = argv[1];  // ---> You can pass port number here, instead of put it in the code

I got this output (client):

toc@UnixServer:~$ ./ssl_client 
Connected with AES256-SHA encryption
Server certificates:
Subject: /C=FR/ST=Some-State/L=PARIS/O=TOC/OU=TOC/CN=TOC/[email protected]
Issuer: /C=FR/ST=Some-State/L=PARIS/O=TOC/OU=TOC/CN=TOC/[email protected]
Received: "<html><body><pre>Hello???</pre></body></html>

"

And this output (server):

Connection: 127.0.0.1:59066
Server certificates:
Subject: /C=FR/ST=Some-State/L=PARIS/O=TOC/OU=TOC/CN=TOC/[email protected]
Issuer: /C=FR/ST=Some-State/L=PARIS/O=TOC/OU=TOC/CN=TOC/[email protected]
Client msg: "Hello???"

When you use a tool like ssldump (http://www.rtfm.com/ssldump/) (on unix box), you can see clearly what's going on:

toc@UnixServer:~$sudo ssldump -i lo port 5000
New TCP connection #1: localhost(59071) <-> localhost(5000)
1 1  0.0012 (0.0012)  C>S  Handshake
      ClientHello
        Version 3.0 
        cipher suites
        Unknown value 0xc014
        Unknown value 0xc00a
        SSL_DHE_RSA_WITH_AES_256_CBC_SHA
        SSL_DHE_DSS_WITH_AES_256_CBC_SHA
        Unknown value 0x88
        Unknown value 0x87
        Unknown value 0xc00f
        Unknown value 0xc005
        SSL_RSA_WITH_AES_256_CBC_SHA
        Unknown value 0x84
        Unknown value 0xc012
        Unknown value 0xc008
        SSL_DHE_RSA_WITH_3DES_EDE_CBC_SHA
        SSL_DHE_DSS_WITH_3DES_EDE_CBC_SHA
        Unknown value 0xc00d
        Unknown value 0xc003
        SSL_RSA_WITH_3DES_EDE_CBC_SHA
        Unknown value 0xc013
        Unknown value 0xc009
        SSL_DHE_RSA_WITH_AES_128_CBC_SHA
        SSL_DHE_DSS_WITH_AES_128_CBC_SHA
        Unknown value 0x9a
        Unknown value 0x99
        Unknown value 0x45
        Unknown value 0x44
        Unknown value 0xc00e
        Unknown value 0xc004
        SSL_RSA_WITH_AES_128_CBC_SHA
        Unknown value 0x96
        Unknown value 0x41
        Unknown value 0xc011
        Unknown value 0xc007
        Unknown value 0xc00c
        Unknown value 0xc002
        SSL_RSA_WITH_RC4_128_SHA
        SSL_RSA_WITH_RC4_128_MD5
        SSL_DHE_RSA_WITH_DES_CBC_SHA
        SSL_DHE_DSS_WITH_DES_CBC_SHA
        SSL_RSA_WITH_DES_CBC_SHA
        SSL_DHE_RSA_EXPORT_WITH_DES40_CBC_SHA
        SSL_DHE_DSS_EXPORT_WITH_DES40_CBC_SHA
        SSL_RSA_EXPORT_WITH_DES40_CBC_SHA
        SSL_RSA_EXPORT_WITH_RC2_CBC_40_MD5
        SSL_RSA_EXPORT_WITH_RC4_40_MD5
        Unknown value 0xff
        compression methods
                unknown value
                  NULL
1 2  0.0019 (0.0006)  S>C  Handshake
      ServerHello
        Version 3.0 
        session_id[32]=
          13 e2 5a f0 10 93 18 56 c8 66 54 94 29 ab 8b 2d 
          7b c6 9c 3b 7b ea c7 54 e6 86 7d 3a 56 8c 96 14 
        cipherSuite         SSL_RSA_WITH_AES_256_CBC_SHA
        compressionMethod                 unknown value
1 3  0.0019 (0.0000)  S>C  Handshake
      Certificate
1 4  0.0019 (0.0000)  S>C  Handshake
      CertificateRequest
        certificate_types                   rsa_sign
        certificate_types                   dss_sign
      ServerHelloDone
1 5  0.0155 (0.0136)  C>S  Handshake
      Certificate
1 6  0.0155 (0.0000)  C>S  Handshake
      ClientKeyExchange
1 7  0.0155 (0.0000)  C>S  Handshake
      CertificateVerify
        Signature[128]=
          ac 94 31 89 64 75 20 5f 4f 00 73 4e e8 de 51 b7 
          f1 bb 16 da 63 b1 8d e9 15 9b af f8 32 d7 84 f5 
          b5 7d 4f 48 1c 2b 41 58 81 d3 a8 50 40 25 90 95 
          44 de 9d bb c4 79 5c 64 a8 a9 28 f4 16 7c 0e 17 
          b2 77 cf b0 8c a9 90 50 34 a5 76 a2 57 39 8d 37 
          12 d8 a5 8d f4 08 3a 1e 83 7e 6c 0a e9 75 ec 85 
          3d 56 f2 2e 4a 7d 71 88 29 26 99 40 43 4e f3 29 
          26 bf eb 15 be 36 22 72 f3 d9 be 4a e3 c9 0b cc 
1 8  0.0155 (0.0000)  C>S  ChangeCipherSpec
1 9  0.0155 (0.0000)  C>S  Handshake
1 10 0.0245 (0.0089)  S>C  ChangeCipherSpec
1 11 0.0245 (0.0000)  S>C  Handshake
1 12 0.0250 (0.0005)  C>S  application_data
1 13 0.0250 (0.0000)  C>S  application_data
1 14 0.0258 (0.0007)  S>C  application_data
1 15 0.0258 (0.0000)  S>C  application_data
1    0.0261 (0.0002)  C>S  TCP FIN
1    0.0275 (0.0013)  S>C  TCP FIN

Regards.

1
votes

As I was saying in comments to one of your previous question, the fact that you get "Malformed Packet: GSM over IP" or something odd here is normal.

You're using port 5000, which is normally reserved for protocol commplex-main. Therefore, without any extra information, Wireshark tries to analyse the traffic it sees with the commplex-main decoders.

Of course, since the data you're exchanging on that port is in fact SSL/TLS (because you're using a port that's not normally used for that), decoding it as if it was commplex-main leads to a number of odd messages regarding malformed packets.

Wireshark only guesses the protocol using the port number it sees. You have to tell it to try a different decoder, if you're not using the standard port for that protocol.

More specifically, right click on a packet and choose Decode As... -> Transport -> SSL.