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/*
* Author: Tatu Ylonen <ylo@cs.hut.fi>
* Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
* All rights reserved
* Created: Sat Mar 18 16:36:11 1995 ylo
* Ssh client program. This program can be used to log into a remote machine.
* The software supports strong authentication, encryption, and forwarding
* of X11, TCP/IP, and authentication connections.
*
* Modified to work with SSL by Niels Provos <provos@citi.umich.edu> in Canada.
*/
#include "includes.h"
RCSID("$Id: ssh.c,v 1.11 1999/11/24 13:26:23 damien Exp $");
#include "xmalloc.h"
#include "ssh.h"
#include "packet.h"
#include "buffer.h"
#include "authfd.h"
#include "readconf.h"
#include "uidswap.h"
#ifdef HAVE___PROGNAME
extern char *__progname;
#else /* HAVE___PROGNAME */
const char *__progname = "ssh";
#endif /* HAVE___PROGNAME */
/* Flag indicating whether debug mode is on. This can be set on the command line. */
int debug_flag = 0;
/* Flag indicating whether to allocate a pseudo tty. This can be set on the command
line, and is automatically set if no command is given on the command line. */
int tty_flag = 0;
/* Flag indicating that nothing should be read from stdin. This can be set
on the command line. */
int stdin_null_flag = 0;
/* Flag indicating that ssh should fork after authentication. This is useful
so that the pasphrase can be entered manually, and then ssh goes to the
background. */
int fork_after_authentication_flag = 0;
/* General data structure for command line options and options configurable
in configuration files. See readconf.h. */
Options options;
/* Name of the host we are connecting to. This is the name given on the
command line, or the HostName specified for the user-supplied name
in a configuration file. */
char *host;
/* socket address the host resolves to */
struct sockaddr_in hostaddr;
/* Flag to indicate that we have received a window change signal which has
not yet been processed. This will cause a message indicating the new
window size to be sent to the server a little later. This is volatile
because this is updated in a signal handler. */
volatile int received_window_change_signal = 0;
/* Value of argv[0] (set in the main program). */
char *av0;
/* Flag indicating whether we have a valid host private key loaded. */
int host_private_key_loaded = 0;
/* Host private key. */
RSA *host_private_key = NULL;
/* Original real UID. */
uid_t original_real_uid;
/* Prints a help message to the user. This function never returns. */
void
usage()
{
fprintf(stderr, "Usage: %s [options] host [command]\n", av0);
fprintf(stderr, "Options:\n");
fprintf(stderr, " -l user Log in using this user name.\n");
fprintf(stderr, " -n Redirect input from /dev/null.\n");
fprintf(stderr, " -a Disable authentication agent forwarding.\n");
#ifdef AFS
fprintf(stderr, " -k Disable Kerberos ticket and AFS token forwarding.\n");
#endif /* AFS */
fprintf(stderr, " -x Disable X11 connection forwarding.\n");
fprintf(stderr, " -i file Identity for RSA authentication (default: ~/.ssh/identity).\n");
fprintf(stderr, " -t Tty; allocate a tty even if command is given.\n");
fprintf(stderr, " -v Verbose; display verbose debugging messages.\n");
fprintf(stderr, " -V Display version number only.\n");
fprintf(stderr, " -P Don't allocate a privileged port.\n");
fprintf(stderr, " -q Quiet; don't display any warning messages.\n");
fprintf(stderr, " -f Fork into background after authentication.\n");
fprintf(stderr, " -e char Set escape character; ``none'' = disable (default: ~).\n");
fprintf(stderr, " -c cipher Select encryption algorithm: "
"``3des'', "
"``blowfish''\n");
fprintf(stderr, " -p port Connect to this port. Server must be on the same port.\n");
fprintf(stderr, " -L listen-port:host:port Forward local port to remote address\n");
fprintf(stderr, " -R listen-port:host:port Forward remote port to local address\n");
fprintf(stderr, " These cause %s to listen for connections on a port, and\n", av0);
fprintf(stderr, " forward them to the other side by connecting to host:port.\n");
fprintf(stderr, " -C Enable compression.\n");
fprintf(stderr, " -g Allow remote hosts to connect to forwarded ports.\n");
fprintf(stderr, " -o 'option' Process the option as if it was read from a configuration file.\n");
exit(1);
}
/*
* Connects to the given host using rsh (or prints an error message and exits
* if rsh is not available). This function never returns.
*/
void
rsh_connect(char *host, char *user, Buffer * command)
{
char *args[10];
int i;
log("Using rsh. WARNING: Connection will not be encrypted.");
/* Build argument list for rsh. */
i = 0;
args[i++] = _PATH_RSH;
/* host may have to come after user on some systems */
args[i++] = host;
if (user) {
args[i++] = "-l";
args[i++] = user;
}
if (buffer_len(command) > 0) {
buffer_append(command, "\0", 1);
args[i++] = buffer_ptr(command);
}
args[i++] = NULL;
if (debug_flag) {
for (i = 0; args[i]; i++) {
if (i != 0)
fprintf(stderr, " ");
fprintf(stderr, "%s", args[i]);
}
fprintf(stderr, "\n");
}
execv(_PATH_RSH, args);
perror(_PATH_RSH);
exit(1);
}
/*
* Main program for the ssh client.
*/
int
main(int ac, char **av)
{
int i, opt, optind, type, exit_status, ok, fwd_port, fwd_host_port,
authfd;
char *optarg, *cp, buf[256];
Buffer command;
struct winsize ws;
struct stat st;
struct passwd *pw, pwcopy;
int interactive = 0, dummy;
uid_t original_effective_uid;
int plen;
/* Save the original real uid. It will be needed later
(uid-swapping may clobber the real uid). */
original_real_uid = getuid();
original_effective_uid = geteuid();
/* If we are installed setuid root be careful to not drop core. */
if (original_real_uid != original_effective_uid) {
struct rlimit rlim;
rlim.rlim_cur = rlim.rlim_max = 0;
if (setrlimit(RLIMIT_CORE, &rlim) < 0)
fatal("setrlimit failed: %.100s", strerror(errno));
}
/* Use uid-swapping to give up root privileges for the duration of
option processing. We will re-instantiate the rights when we
are ready to create the privileged port, and will permanently
drop them when the port has been created (actually, when the
connection has been made, as we may need to create the port
several times). */
temporarily_use_uid(original_real_uid);
/* Set our umask to something reasonable, as some files are
created with the default umask. This will make them
world-readable but writable only by the owner, which is ok for
all files for which we don't set the modes explicitly. */
umask(022);
/* Save our own name. */
av0 = av[0];
/* Initialize option structure to indicate that no values have been set. */
initialize_options(&options);
/* Parse command-line arguments. */
host
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