414 строки
12 KiB
C
414 строки
12 KiB
C
/* This is a sample implementation of a libssh based SSH server */
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/*
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Copyright 2003-2011 Aris Adamantiadis
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This file is part of the SSH Library
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You are free to copy this file, modify it in any way, consider it being public
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domain. This does not apply to the rest of the library though, but it is
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allowed to cut-and-paste working code from this file to any license of
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program.
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The goal is to show the API in action. It's not a reference on how terminal
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clients must be made or how a client should react.
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*/
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#include "config.h"
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#include <libssh/libssh.h>
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#include <libssh/server.h>
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#ifdef HAVE_ARGP_H
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#include <argp.h>
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#endif
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#define SSHD_USER "libssh"
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#define SSHD_PASSWORD "libssh"
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#ifndef KEYS_FOLDER
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#ifdef _WIN32
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#define KEYS_FOLDER
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#else
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#define KEYS_FOLDER "/etc/ssh/"
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#endif
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#endif
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static int port = 22;
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#ifdef WITH_PCAP
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static const char *pcap_file = "debug.server.pcap";
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static ssh_pcap_file pcap;
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static void set_pcap(ssh_session session){
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if(!pcap_file)
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return;
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pcap=ssh_pcap_file_new();
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if(ssh_pcap_file_open(pcap,pcap_file) == SSH_ERROR){
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printf("Error opening pcap file\n");
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ssh_pcap_file_free(pcap);
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pcap=NULL;
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return;
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}
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ssh_set_pcap_file(session,pcap);
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}
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static void cleanup_pcap(void) {
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ssh_pcap_file_free(pcap);
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pcap=NULL;
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}
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#endif
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static int auth_password(const char *user, const char *password){
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if(strcmp(user, SSHD_USER))
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return 0;
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if(strcmp(password, SSHD_PASSWORD))
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return 0;
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return 1; // authenticated
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}
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#ifdef HAVE_ARGP_H
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const char *argp_program_version = "libssh server example "
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SSH_STRINGIFY(LIBSSH_VERSION);
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const char *argp_program_bug_address = "<libssh@libssh.org>";
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/* Program documentation. */
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static char doc[] = "libssh -- a Secure Shell protocol implementation";
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/* A description of the arguments we accept. */
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static char args_doc[] = "BINDADDR";
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/* The options we understand. */
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static struct argp_option options[] = {
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{
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.name = "port",
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.key = 'p',
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.arg = "PORT",
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.flags = 0,
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.doc = "Set the port to bind.",
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.group = 0
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},
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{
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.name = "hostkey",
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.key = 'k',
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.arg = "FILE",
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.flags = 0,
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.doc = "Set the host key.",
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.group = 0
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},
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{
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.name = "dsakey",
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.key = 'd',
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.arg = "FILE",
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.flags = 0,
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.doc = "Set the dsa key.",
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.group = 0
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},
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{
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.name = "rsakey",
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.key = 'r',
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.arg = "FILE",
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.flags = 0,
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.doc = "Set the rsa key.",
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.group = 0
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},
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{
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.name = "verbose",
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.key = 'v',
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.arg = NULL,
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.flags = 0,
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.doc = "Get verbose output.",
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.group = 0
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},
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{NULL, 0, 0, 0, NULL, 0}
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};
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/* Parse a single option. */
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static error_t parse_opt (int key, char *arg, struct argp_state *state) {
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/* Get the input argument from argp_parse, which we
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* know is a pointer to our arguments structure.
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*/
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ssh_bind sshbind = state->input;
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switch (key) {
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case 'p':
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDPORT_STR, arg);
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port = atoi(arg);
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break;
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case 'd':
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_DSAKEY, arg);
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break;
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case 'k':
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_HOSTKEY, arg);
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break;
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case 'r':
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_RSAKEY, arg);
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break;
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case 'v':
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_LOG_VERBOSITY_STR, "3");
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break;
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case ARGP_KEY_ARG:
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if (state->arg_num >= 1) {
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/* Too many arguments. */
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argp_usage (state);
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}
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_BINDADDR, arg);
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break;
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case ARGP_KEY_END:
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if (state->arg_num < 1) {
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/* Not enough arguments. */
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argp_usage (state);
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}
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break;
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default:
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return ARGP_ERR_UNKNOWN;
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}
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return 0;
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}
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/* Our argp parser. */
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static struct argp argp = {options, parse_opt, args_doc, doc, NULL, NULL, NULL};
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#endif /* HAVE_ARGP_H */
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static const char *name;
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static const char *instruction;
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static const char *prompts[2];
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static char echo[] = { 1, 0 };
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static int kbdint_check_response(ssh_session session) {
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int count;
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count = ssh_userauth_kbdint_getnanswers(session);
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if(count != 2) {
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instruction = "Something weird happened :(";
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return 0;
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}
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if(strcasecmp("Arthur Dent",
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ssh_userauth_kbdint_getanswer(session, 0)) != 0) {
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instruction = "OK, this is not YOUR name, "
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"but it's a reference to the HGTG...";
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prompts[0] = "The main character's full name: ";
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return 0;
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}
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if(strcmp("42", ssh_userauth_kbdint_getanswer(session, 1)) != 0) {
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instruction = "Make an effort !!! What is the Answer to the Ultimate "
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"Question of Life, the Universe, and Everything ?";
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prompts[1] = "Answer to the Ultimate Question of Life, the Universe, "
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"and Everything: ";
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return 0;
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}
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return 1;
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}
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static int authenticate(ssh_session session) {
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ssh_message message;
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name = "\n\nKeyboard-Interactive Fancy Authentication\n";
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instruction = "Please enter your real name and your password";
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prompts[0] = "Real name: ";
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prompts[1] = "Password: ";
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do {
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message=ssh_message_get(session);
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if(!message)
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break;
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switch(ssh_message_type(message)){
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case SSH_REQUEST_AUTH:
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switch(ssh_message_subtype(message)){
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case SSH_AUTH_METHOD_PASSWORD:
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printf("User %s wants to auth with pass %s\n",
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ssh_message_auth_user(message),
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ssh_message_auth_password(message));
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if(auth_password(ssh_message_auth_user(message),
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ssh_message_auth_password(message))){
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ssh_message_auth_reply_success(message,0);
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ssh_message_free(message);
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return 1;
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}
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ssh_message_auth_set_methods(message,
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SSH_AUTH_METHOD_PASSWORD |
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SSH_AUTH_METHOD_INTERACTIVE);
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// not authenticated, send default message
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ssh_message_reply_default(message);
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break;
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case SSH_AUTH_METHOD_INTERACTIVE:
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if(!ssh_message_auth_kbdint_is_response(message)) {
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printf("User %s wants to auth with kbdint\n",
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ssh_message_auth_user(message));
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ssh_message_auth_interactive_request(message, name,
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instruction, 2, prompts, echo);
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} else {
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if(kbdint_check_response(session)) {
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ssh_message_auth_reply_success(message,0);
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ssh_message_free(message);
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return 1;
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}
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ssh_message_auth_set_methods(message,
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SSH_AUTH_METHOD_PASSWORD |
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SSH_AUTH_METHOD_INTERACTIVE);
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ssh_message_reply_default(message);
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}
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break;
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case SSH_AUTH_METHOD_NONE:
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default:
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printf("User %s wants to auth with unknown auth %d\n",
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ssh_message_auth_user(message),
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ssh_message_subtype(message));
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ssh_message_auth_set_methods(message,
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SSH_AUTH_METHOD_PASSWORD |
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SSH_AUTH_METHOD_INTERACTIVE);
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ssh_message_reply_default(message);
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break;
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}
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break;
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default:
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ssh_message_auth_set_methods(message,
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SSH_AUTH_METHOD_PASSWORD |
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SSH_AUTH_METHOD_INTERACTIVE);
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ssh_message_reply_default(message);
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}
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ssh_message_free(message);
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} while (1);
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return 0;
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}
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int main(int argc, char **argv){
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ssh_session session;
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ssh_bind sshbind;
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ssh_message message;
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ssh_channel chan=0;
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char buf[2048];
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int auth=0;
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int shell=0;
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int i;
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int r;
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sshbind=ssh_bind_new();
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session=ssh_new();
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_DSAKEY,
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KEYS_FOLDER "ssh_host_dsa_key");
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ssh_bind_options_set(sshbind, SSH_BIND_OPTIONS_RSAKEY,
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KEYS_FOLDER "ssh_host_rsa_key");
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#ifdef HAVE_ARGP_H
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/*
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* Parse our arguments; every option seen by parse_opt will
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* be reflected in arguments.
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*/
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argp_parse (&argp, argc, argv, 0, 0, sshbind);
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#else
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(void) argc;
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(void) argv;
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#endif
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#ifdef WITH_PCAP
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set_pcap(session);
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#endif
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if(ssh_bind_listen(sshbind)<0){
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printf("Error listening to socket: %s\n", ssh_get_error(sshbind));
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return 1;
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}
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printf("Started sample libssh sshd on port %d\n", port);
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printf("You can login as the user %s with the password %s\n", SSHD_USER,
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SSHD_PASSWORD);
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r = ssh_bind_accept(sshbind, session);
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if(r==SSH_ERROR){
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printf("Error accepting a connection: %s\n", ssh_get_error(sshbind));
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return 1;
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}
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if (ssh_handle_key_exchange(session)) {
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printf("ssh_handle_key_exchange: %s\n", ssh_get_error(session));
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return 1;
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}
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/* proceed to authentication */
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auth = authenticate(session);
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if(!auth){
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printf("Authentication error: %s\n", ssh_get_error(session));
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ssh_disconnect(session);
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return 1;
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}
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/* wait for a channel session */
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do {
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message = ssh_message_get(session);
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if(message){
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if(ssh_message_type(message) == SSH_REQUEST_CHANNEL_OPEN &&
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ssh_message_subtype(message) == SSH_CHANNEL_SESSION) {
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chan = ssh_message_channel_request_open_reply_accept(message);
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ssh_message_free(message);
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break;
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} else {
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ssh_message_reply_default(message);
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ssh_message_free(message);
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}
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} else {
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break;
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}
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} while(!chan);
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if(!chan) {
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printf("Error: cleint did not ask for a channel session (%s)\n",
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ssh_get_error(session));
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ssh_finalize();
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return 1;
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}
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/* wait for a shell */
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do {
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message = ssh_message_get(session);
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if(message != NULL) {
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if(ssh_message_type(message) == SSH_REQUEST_CHANNEL &&
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ssh_message_subtype(message) == SSH_CHANNEL_REQUEST_SHELL) {
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shell = 1;
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ssh_message_channel_request_reply_success(message);
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ssh_message_free(message);
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break;
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}
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ssh_message_reply_default(message);
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ssh_message_free(message);
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} else {
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break;
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}
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} while(!shell);
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if(!shell) {
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printf("Error: No shell requested (%s)\n", ssh_get_error(session));
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return 1;
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}
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printf("it works !\n");
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do{
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i=ssh_channel_read(chan,buf, 2048, 0);
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if(i>0) {
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if(*buf == '' || *buf == '')
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break;
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if(i == 1 && *buf == '\r')
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ssh_channel_write(chan, "\r\n", 2);
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else
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ssh_channel_write(chan, buf, i);
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if (write(1,buf,i) < 0) {
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printf("error writing to buffer\n");
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return 1;
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}
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}
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} while (i>0);
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ssh_channel_close(chan);
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ssh_disconnect(session);
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ssh_bind_free(sshbind);
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#ifdef WITH_PCAP
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cleanup_pcap();
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#endif
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ssh_finalize();
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return 0;
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}
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