/* Copyright (GPL), 2004 Mike Chirico mchirico@comcast.net or mchirico@users.sourceforge.net
http://prdownloads.sourceforge.net/souptonuts/working_with_time.tar.gz?download
This program queries a timeserver on UDP port 123 and allows us to peek at
at the NTP timestamp format.
Run this program as follows:
$ ./queryTimeServer <timeserver>
or
$ ./queryTimeServer timeserver1.upenn.edu
Compile:
$ gcc -o queryTimeServer -Wall -W -O2 -s -pipe queryTimeServer.c
Need a list of Public NTP Secondary (stratum 2) Time Servers?
http://www.eecis.udel.edu/~mills/ntp/clock2b.html
A good reference of the standard:
http://www.eecis.udel.edu/~mills/database/rfc/rfc2030.txt
Below is a description of the NTP/SNTP Version 4 message format,
which follows the IP and UDP headers. This format is identical to
that described in RFC-1305, with the exception of the contents of the
reference identifier field. The header fields are defined as follows:
1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|LI | VN |Mode | Stratum | Poll | Precision |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Root Delay |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Root Dispersion |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Reference Identifier |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Reference Timestamp (64) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Originate Timestamp (64) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Receive Timestamp (64) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| Transmit Timestamp (64) |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Key Identifier (optional) (32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| |
| Message Digest (optional) (128) |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Reference Timestamp: This is the time at which the local clock was
last set or corrected, in 64-bit timestamp format.
Originate Timestamp: This is the time at which the request departed
the client for the server, in 64-bit timestamp format.
Receive Timestamp: This is the time at which the request arrived at
the server, in 64-bit timestamp format.
Transmit Timestamp: This is the time at which the reply departed the
server for the client, in 64-bit timestamp format.
*/
#include <arpa/inet.h>
#include <assert.h>
#include <errno.h>
#include <netinet/in.h>
#include <signal.h>
#include <sys/time.h>
#include <time.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/wait.h>
#include <netdb.h>
#include <unistd.h>
#include <stdint.h>
/*
* Time of day conversion constant. Ntp's time scale starts in 1900,
* Unix in 1970.
*/
#define JAN_1970 0x83aa7e80 /* 2208988800 1970 - 1900 in seconds */
#define NTP_TO_UNIX(n,u) do { u = n - JAN_1970; } while (0)
#define HTONL_FP(h, n) do { (n)->l_ui = htonl((h)->l_ui); \
(n)->l_uf = htonl((h)->l_uf); } while (0)
#define NTOHL_FP(n, h) do { (h)->l_ui = ntohl((n)->l_ui); \
(h)->l_uf = ntohl((n)->l_uf); } while (0)
#define SA struct sockaddr
#define MAXLINE 16384
#define READMAX 16384 //must be less than MAXLINE or equal
#define NUM_BLK 20
#define MAXSUB 512
#define URL_LEN 256
#define MAXHSTNAM 512
#define MAXPAGE 1024
#define MAXPOST 1638
#define LISTENQ 1024
extern int h_errno;
/*
* NTP uses two fixed point formats. The first (l_fp) is the "long"
* format and is 64 bits long with the decimal between bits 31 and 32.
* This is used for time stamps in the NTP packet header (in network
* byte order) and for internal computations of offsets (in local host
* byte order). We use the same structure for both signed and unsigned
* values, which is a big hack but saves rewriting all the operators
* twice. Just to confuse this, we also sometimes just carry the
* fractional part in calculations, in both signed and unsigned forms.
* Anyway, an l_fp looks like:
*
* 0 1 2 3
* 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Integral Part |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* | Fractional Part |
* +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
* REF http://www.eecis.udel.edu/~mills/database/rfc/rfc2030.txt
*/
typedef struct {
union {
uint32_t Xl_ui;
int32_t Xl_i;
} Ul_i;
union {
uint32_t Xl_uf;
int32_t Xl_f;
} Ul_f;
} l_fp;
#define l_ui Ul_i.Xl_ui /* unsigned integral part */
#define l_i Ul_i.Xl_i /* signed integral part */
#define l_uf Ul_f.Xl_uf /* unsigned fractional part */
#define l_f Ul_f.Xl_f /* signed fractional part */
#define HTONL_F(f, nts) do { (nts)->l_uf = htonl(f); \
if ((f) & 0x80000000) \
(nts)->l_i = -1; \
else \
(nts)->l_i = 0; \
} while (0)
struct pkt {
uint8_t li_vn_mode; /* leap indicator, version and mode */
uint8_t stratum; /* peer stratum */
uint8_t ppoll; /* peer poll interval */
int8_t precision; /* peer clock precision */
uint32_t rootdelay; /* distance to primary clock */
uint32_t rootdispersion; /* clock dispersion */
uint32_t refid; /* reference clock ID */
l_fp ref; /* time peer clock was last updated */
l_fp org; /* originate time stamp */
l_fp rec; /* receive time stamp */
l_fp xmt; /* transmit time stamp */
#define LEN_PKT_NOMAC 12 * sizeof(uint32_t) /* min header length */
#define LEN_PKT_MAC LEN_PKT_NOMAC + sizeof(uint32_t)
#define MIN_MAC_LEN 3 * sizeof(uint32_t) /* DES */
#define MAX_MAC_LEN 5 * sizeof(uint32_t) /* MD5 */
/*
* The length of the packet less MAC must be a multiple of 64
* with an RSA modulus and Diffie-Hellman prime of 64 octets
* and maximum host name of 128 octets, the maximum autokey
* command is 152 octets and maximum autokey response is 460
* octets. A packet can contain no more than one command and one
* response, so the maximum total extension field length is 672
* octets. But, to handle humungus certificates, the bank must
* be broke.
*/
#ifdef OPENSSL
uint32_t exten[NTP_MAXEXTEN / 4]; /* max extension field */
#else /* OPENSSL */
uint32_t exten[1]; /* misused */
#endif /* OPENSSL */
uint8_t mac[MAX_MAC_LEN]; /* mac */
};
void dg_snd( int sockfd, struct sockaddr * pcliaddr, socklen_t servlen)
{
int n;
int len;
char buffer[30];
time_t seconds;
struct pkt *msg;
struct pkt *prt;
msg= (struct pkt *) malloc(sizeof(struct pkt)*1);
prt= (struct pkt *) malloc(sizeof(struct pkt)*1);
msg->li_vn_mode=227;
msg->stratum=0;
msg->ppoll=4;
msg->precision=0;
msg->rootdelay=0;
msg->rootdispersion=0;
msg->ref.Ul_i.Xl_i=0;
msg->ref.Ul_f.Xl_f=0;
msg->org.Ul_i.Xl_i=0;
msg->org.Ul_f.Xl_f=0;
msg->rec.Ul_i.Xl_i=0;
msg->rec.Ul_f.Xl_f=0;
msg->xmt.Ul_i.Xl_i=0;
msg->xmt.Ul_f.Xl_f=0;
fprintf(stderr,"************* INITIAL VALUES BEFORE SEND *******************\n");
fprintf(stderr,"li_vn_mode %Xh size %d\n",msg->li_vn_mode,sizeof(msg->li_vn_mode) );
fprintf(stderr,"stratum %d size %d\n",msg->stratum,sizeof(msg->stratum));
fprintf(stderr,"ppoll %d size %d\n",msg->ppoll,sizeof(msg->ppoll));
fprintf(stderr,"precision %d size %d\n",msg->precision,sizeof(msg->precision));
fprintf(stderr,"rootdelay %d size %d\n",msg->rootdelay,sizeof(msg->rootdelay));
fprintf(stderr,"rootdispersion %d %d\n",msg->rootdispersion,sizeof(msg->rootdispersion));
fprintf(stderr,"refid %d size %d\n",msg->refid,sizeof(msg->refid));
fprintf(stderr,"ref %u %d\n",msg->ref.Ul_i.Xl_ui,sizeof(msg->ref.Ul_i));
fprintf(stderr,"ref %u %d\n",msg->ref.Ul_f.Xl_f,sizeof(msg->ref.Ul_f));
fprintf(stderr,"org %u %d\n",msg->ref.Ul_i.Xl_ui,sizeof(msg->ref.Ul_i));
fprintf(stderr,"org %u %d\n",msg->ref.Ul_f.Xl_f,sizeof(msg->ref.Ul_f));
fprintf(stderr,"org %u %d\n",msg->org.Ul_i.Xl_ui,sizeof(msg->org.Ul_i));
fprintf(stderr,"org %u %d\n",msg->org.Ul_f.Xl_f,sizeof(msg->org.Ul_f));
fprintf(stderr,"rec %u %d\n",msg->rec.Ul_i.Xl_ui,sizeof(msg->rec.Ul_i));
fprintf(stderr,"rec %u %d\n",msg->rec.Ul_f.Xl_f,sizeof(msg->rec.Ul_f));
fprintf(stderr,"xmt %u %d\n",msg->xmt.Ul_i.Xl_ui,sizeof(msg->xmt.Ul_i));
fprintf(stderr,"xmt %u %d\n",msg->xmt.Ul_f.Xl_f,sizeof(msg->xmt.Ul_f));
fprintf(stderr,"************* END INITIAL VALUES BEFORE SEND ***************\n");
len=48;
sendto(sockfd, (char *) msg, len, 0, pcliaddr, servlen);
n = recvfrom(sockfd, msg, len, 0, NULL, NULL);
fprintf(stderr,"\n\n************* 2nd START *******************\n");
fprintf(stderr,"li_vn_mode %Xh size %d\n",msg->li_vn_mode,sizeof(msg->li_vn_mode) );
fprintf(stderr,"stratum %d size %d\n",msg->stratum,sizeof(msg->stratum));
fprintf(stderr,"ppoll %d size %d\n",msg->ppoll,sizeof(msg->ppoll));
fprintf(stderr,"precision %d size %d\n",msg->precision,sizeof(msg->precision));
fprintf(stderr,"rootdelay %Xh size %d\n",ntohl(msg->rootdelay),sizeof(msg->rootdelay));
fprintf(stderr,"rootdispersion %d %d\n",ntohl(msg->rootdispersion),sizeof(msg->rootdispersion));
fprintf(stderr,"refid %d size %d\n",msg->refid,sizeof(msg->refid));
NTOHL_FP(&msg->ref, &prt->ref);
NTOHL_FP(&msg->org, &prt->org);
NTOHL_FP(&msg->rec, &prt->rec);
NTOHL_FP(&msg->xmt, &prt->xmt);
fprintf(stderr,"ref %u %d\n",prt->ref.Ul_i.Xl_ui,sizeof(msg->ref.Ul_i));
fprintf(stderr,"ref %u %d\n",prt->ref.Ul_f.Xl_f,sizeof(msg->ref.Ul_f));
fprintf(stderr,"org %u %d\n",prt->org.Ul_i.Xl_ui,sizeof(prt->org.Ul_i));
fprintf(stderr,"org %u %d\n",prt->org.Ul_f.Xl_f,sizeof(prt->org.Ul_f));
fprintf(stderr,"rec %u %d\n",prt->rec.Ul_i.Xl_ui,sizeof(prt->rec.Ul_i));
fprintf(stderr,"rec %u %d\n",prt->rec.Ul_f.Xl_f,sizeof(prt->rec.Ul_f));
fprintf(stderr,"xmt %u %d\n",prt->xmt.Ul_i.Xl_ui,sizeof(prt->xmt.Ul_i));
fprintf(stderr,"xmt %u %d\n",prt->xmt.Ul_f.Xl_f,sizeof(prt->xmt.Ul_f));
NTP_TO_UNIX(prt->ref.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"\nref: %s.%u\n",buffer,prt->ref.Ul_f.Xl_f);
NTP_TO_UNIX(prt->org.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"org: %s.%u\n",buffer,prt->org.Ul_f.Xl_f);
NTP_TO_UNIX(prt->rec.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"rec: %s.%u\n",buffer,prt->rec.Ul_f.Xl_f);
NTP_TO_UNIX(prt->xmt.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"xmt: %s.%u\n",buffer,prt->xmt.Ul_f.Xl_f);
fprintf(stderr,"************* 2nd STOP *******************\n");
msg->li_vn_mode=227;
msg->stratum=0;
msg->ppoll=4;
msg->precision=-6;
msg->rootdelay=256;
msg->rootdispersion=256;
msg->ref.Ul_i.Xl_i= msg->xmt.Ul_i.Xl_i;
msg->ref.Ul_f.Xl_f= msg->xmt.Ul_f.Xl_f;
msg->org.Ul_i.Xl_i= msg->xmt.Ul_i.Xl_i;
msg->org.Ul_f.Xl_f= msg->xmt.Ul_f.Xl_f;
sendto(sockfd, (char *) msg, len, 0, pcliaddr, servlen);
n = recvfrom(sockfd, msg, len, 0, NULL, NULL);
fprintf(stderr,"\n\n************* 3nd START *******************\n");
fprintf(stderr,"li_vn_mode %Xh size %d\n",msg->li_vn_mode,sizeof(msg->li_vn_mode) );
fprintf(stderr,"stratum %d size %d\n",msg->stratum,sizeof(msg->stratum));
fprintf(stderr,"ppoll %d size %d\n",msg->ppoll,sizeof(msg->ppoll));
fprintf(stderr,"precision %d size %d\n",msg->precision,sizeof(msg->precision));
fprintf(stderr,"rootdelay %Xh size %d\n",ntohl(msg->rootdelay),sizeof(msg->rootdelay));
fprintf(stderr,"rootdispersion %d %d\n",ntohl(msg->rootdispersion),sizeof(msg->rootdispersion));
fprintf(stderr,"refid %d size %d\n",msg->refid,sizeof(msg->refid));
NTOHL_FP(&msg->ref, &prt->ref);
NTOHL_FP(&msg->org, &prt->org);
NTOHL_FP(&msg->rec, &prt->rec);
NTOHL_FP(&msg->xmt, &prt->xmt);
fprintf(stderr,"ref %u %d\n",prt->ref.Ul_i.Xl_ui,sizeof(msg->ref.Ul_i));
fprintf(stderr,"ref %u %d\n",prt->ref.Ul_f.Xl_f,sizeof(msg->ref.Ul_f));
fprintf(stderr,"org %u %d\n",prt->org.Ul_i.Xl_ui,sizeof(prt->org.Ul_i));
fprintf(stderr,"org %u %d\n",prt->org.Ul_f.Xl_f,sizeof(prt->org.Ul_f));
fprintf(stderr,"rec %u %d\n",prt->rec.Ul_i.Xl_ui,sizeof(prt->rec.Ul_i));
fprintf(stderr,"rec %u %d\n",prt->rec.Ul_f.Xl_f,sizeof(prt->rec.Ul_f));
fprintf(stderr,"xmt %u %d\n",prt->xmt.Ul_i.Xl_ui,sizeof(prt->xmt.Ul_i));
fprintf(stderr,"xmt %u %d\n",prt->xmt.Ul_f.Xl_f,sizeof(prt->xmt.Ul_f));
NTP_TO_UNIX(prt->ref.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"\nref: %s.%u\n",buffer,prt->ref.Ul_f.Xl_f);
NTP_TO_UNIX(prt->org.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"org: %s.%u\n",buffer,prt->org.Ul_f.Xl_f);
NTP_TO_UNIX(prt->rec.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"rec: %s.%u\n",buffer,prt->rec.Ul_f.Xl_f);
NTP_TO_UNIX(prt->xmt.Ul_i.Xl_ui, seconds);
strftime(buffer,30,"%m-%d-%Y %T",localtime(&seconds));
fprintf(stderr,"xmt: %s.%u\n",buffer,prt->xmt.Ul_f.Xl_f);
fprintf(stderr,"************* 3nd STOP *******************\n");
free(msg);
free(prt);
}
int main(int argc, char **argv)
{
if (argc < 2) {
fprintf(stderr,
"./queryTimeServer timeserver1.upenn.edu\n"
"or\n"
"./queryTimeServer timex.usg.edu\n"
"./queryTimeServer ntp.linux.org.ve\n"
"./queryTimeServer ntp.pop-pr.rnp.br\n\n"
);
exit(1);
}
int sockfd;
struct sockaddr_in servaddr;
char **pptr;
char str[50];
struct hostent *hptr;
if ((hptr = gethostbyname(argv[1])) == NULL) {
fprintf(stderr, " gethostbyname error for host: %s: %s",
argv[1], hstrerror(h_errno));
exit(1);
}
if (hptr->h_addrtype == AF_INET
&& (pptr = hptr->h_addr_list) != NULL) {
inet_ntop(hptr->h_addrtype, *pptr, str, sizeof(str));
} else {
fprintf(stderr, "Error call inet_ntop \n");
}
sockfd = socket(AF_INET, SOCK_DGRAM, 0);
if (sockfd == -1)
fprintf(stderr,"Error in socket \n");
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
servaddr.sin_port = htons(123);
inet_pton(AF_INET, str, &servaddr.sin_addr);
if (connect(sockfd, (SA *) & servaddr, sizeof(servaddr)) == -1 )
fprintf(stderr,"Error in connect \n");
dg_snd(sockfd, (struct sockaddr *) &servaddr, sizeof(servaddr));
close(sockfd);
exit(0);
}
Linux System Admin Tips: There are over 200 Linux tips and tricks in this article. That is over 100 pages covering everything from NTP, setting up 2 IP address on one NIC, sharing directories among several users, putting running jobs in the background, find out who is doing what on your system by examining open sockets and the ps command, how to watch a file, how to prevent even root from deleting a file, tape commands, setting up cron jobs, using rsync, using screen conveniently with emacs, how to kill every process for a user, security tips and a lot more. These tip grow weekly. The above link will download the text version for easy grep searching. There is also an html version here.
Breaking Firewalls with OpenSSH and PuTTY: If the system administrator deliberately filters out all traffic except port 22 (ssh), to a single server, it is very likely that you can still gain access other computers behind the firewall. This article shows how remote Linux and Windows users can gain access to firewalled samba, mail, and http servers. In essence, it shows how openSSH and Putty can be used as a VPN solution for your home or workplace.
MySQL Tips and Tricks: Find out who is doing what in MySQL and how to kill the process, create binary log files, connect, create and select with Perl and Java, remove duplicates in a table with the index command, rollback and how to apply, merging several tables into one, updating foreign keys, monitor port 3306 with the tcpdump command, creating a C API, complex selects, and much more.
Create a Live Linux CD - BusyBox and OpenSSH Included: These steps will show you how to create a functioning Linux system, with the latest 2.6 kernel compiled from source, and how to integrate the BusyBox utilities including the installation of DHCP. Plus, how to compile in the OpenSSH package on this CD based system. On system boot-up a filesystem will be created and the contents from the CD will be uncompressed and completely loaded into RAM -- the CD could be removed at this point for boot-up on a second computer. The remaining functioning system will have full ssh capabilities. You can take over any PC assuming, of course, you have configured the kernel with the appropriate drivers and the PC can boot from a CD. This tutorial steps you through the whole processes.
SQLite Tutorial : This article explores the power and simplicity of sqlite3, first by starting with common commands and triggers, then the attach statement with the union operation is introduced in a way that allows multiple tables, in separate databases, to be combined as one virtual table, without the overhead of copying or moving data. Next, the simple sign function and the amazingly powerful trick of using this function in SQL select statements to solve complex queries with a single pass through the data is demonstrated, after making a brief mathematical case for how the sign function defines the absolute value and IF conditions.
The Lemon Parser Tutorial: This article explains how to build grammars and programs using the lemon parser, which is faster than yacc. And, unlike yacc, it is thread safe.
How to Compile the 2.6 kernel for Red Hat 9 and 8.0 and get Fedora Updates: This is a step by step tutorial on how to compile the 2.6 kernel from source.
Virtual Filesystem: Building A Linux Filesystem From An Ordinary File. You can take a disk file, format it as ext2, ext3, or reiser filesystem and then mount it, just like a physical drive. Yes, it then possible to read and write files to this newly mounted device. You can also copy the complete filesystem, since it is just a file, to another computer. If security is an issue, read on. This article will show you how to encrypt the filesystem, and mount it with ACL (Access Control Lists), which give you rights beyond the traditional read (r) write (w) and execute (x) for the 3 user groups file, owner and other.
Working With Time: What? There are 61 seconds in a minute? We can go back in time? We still tell time by the sun?
Mike Chirico, a father of triplets (all girls) lives outside of
Philadelphia, PA, USA. He has worked with Linux since 1996, has a Masters
in Computer Science and Mathematics from Villanova University, and has
worked in computer-related jobs from Wall Street to the University of
Pennsylvania. His hero is Paul Erdos, a brilliant number theorist who was
known for his open collaboration with others.
Mike's notes page is souptonuts. For
open source consulting needs, please send an email to
mchirico@gmail.com. All consulting work must include a donation to
SourceForge.net.
