使用libssh链接远程ssh服务器并执行command

看到段牛牛和大湿聊了一下批量ssh的东西，然后看到有个ssh的程序，

挺有意思，学习一下，然后实现了一下，记录下来了

1. #include <stdio.h>
2. #include <stdlib.h>
3. #include <string.h>
4. #include <unistd.h>
5. #include <libssh/libssh.h>
8. int show_remote_processes(ssh_session session, unsigned char *command)
9. {
10.     ssh_channel channel;
11. int rc;
12.     char buffer[256];
13.     unsigned int nbytes;
15.     channel = ssh_channel_new(session);
16. if (channel == NULL)
17.         return SSH_ERROR;
19.     rc = ssh_channel_open_session(channel);
20. if (rc != SSH_OK)
21. {
22.         ssh_channel_free(channel);
23.         return rc;
24. }
26.     rc = ssh_channel_request_exec(channel, command);
27. if (rc != SSH_OK)
28. {
29.         ssh_channel_close(channel);
30.         ssh_channel_free(channel);
31.         return rc;
32. }
34.     nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
35. while (nbytes > 0)
36. {
37. if (write(1, buffer, nbytes) != nbytes)
38. {
39.             ssh_channel_close(channel);
40.             ssh_channel_free(channel);
41.             return SSH_ERROR;
42. }
43.         nbytes = ssh_channel_read(channel, buffer, sizeof(buffer), 0);
44. }
46. if (nbytes < 0)
47. {
48.         ssh_channel_close(channel);
49.         ssh_channel_free(channel);
50.         return SSH_ERROR;
51. }
53.     ssh_channel_send_eof(channel);
54.     ssh_channel_close(channel);
55.     ssh_channel_free(channel);
57.     return SSH_OK;
58. }
60. int verify_knownhost(ssh_session session)
61. {
62. int state, hlen;
63.     unsigned char *hash = NULL;
64.     char *hexa;
65.     char buf[10];
67.     state = ssh_is_server_known(session);
69.     hlen = ssh_get_pubkey_hash(session, &hash);
70. if (hlen < 0)
71.         return -1;
73.     switch (state)
74. {
75. case SSH_SERVER_KNOWN_OK:
76.             break; /* ok */
78. case SSH_SERVER_KNOWN_CHANGED:
79.             fprintf(stderr, "Host key for server changed: it is now:\n");
80.             ssh_print_hexa("Public key hash", hash, hlen);
81.             fprintf(stderr, "For security reasons, connection will be stopped\n");
82.             free(hash);
83.             return -1;
85. case SSH_SERVER_FOUND_OTHER:
86.             fprintf(stderr, "The host key for this server was not found but an other"
87. "type of key exists.\n");
88.             fprintf(stderr, "An attacker might change the default server key to"
89. "confuse your client into thinking the key does not exist\n");
90.             free(hash);
91.             return -1;
93. case SSH_SERVER_FILE_NOT_FOUND:
94.             fprintf(stderr, "Could not find known host file.\n");
95.             fprintf(stderr, "If you accept the host key here, the file will be"
96. "automatically created.\n");
97. /* fallback to SSH_SERVER_NOT_KNOWN behavior */
99. case SSH_SERVER_NOT_KNOWN:
100.             hexa = ssh_get_hexa(hash, hlen);
101.             fprintf(stderr,"The server is unknown. Do you trust the host key?\n");
102.             fprintf(stderr, "Public key hash: %s\n", hexa);
103.             free(hexa);
104. if (fgets(buf, sizeof(buf), stdin) == NULL)
105. {
106.                 free(hash);
107.                 return -1;
108. }
109. if (strncasecmp(buf, "yes", 3) != 0)
110. {
111.                 free(hash);
112.                 return -1;
113. }
114. if (ssh_write_knownhost(session) < 0)
115. {
116.                 fprintf(stderr, "Error %s\n", "error");
117.                 free(hash);
118.                 return -1;
119. }
120.             break;
122. case SSH_SERVER_ERROR:
123.             fprintf(stderr, "Error %s", ssh_get_error(session));
124.             free(hash);
125.             return -1;
126. }
128.     free(hash);
129.     return 0;
130. }
133. static int ssh_connect_test(unsigned char *ipaddr, unsigned char *command)
134. {
135. int rc = 0;
136.     char *password;
137.     ssh_session my_ssh_session = ssh_new();
139. if (!my_ssh_session) {
140.         fprintf(stderr, "cannot alloc new ssh\r\n");
141.         return -1;
142. }
143.     ssh_options_set(my_ssh_session, SSH_OPTIONS_HOST, ipaddr);
145.     rc = ssh_connect(my_ssh_session);
146. if (rc != SSH_OK)
147. {
148.         fprintf(stderr, "Error connecting to localhost: %s\n", ssh_get_error(my_ssh_session));
149. exit(-1);
150. }
153. if (verify_knownhost(my_ssh_session) < 0)
154. {
155.         ssh_disconnect(my_ssh_session);
156.         ssh_free(my_ssh_session);
157. exit(-1);
158. }
161.     password = "passwordsamples";
162.     rc = ssh_userauth_password(my_ssh_session, NULL, password);
163. if (rc != SSH_AUTH_SUCCESS)
164. {
165.         fprintf(stderr, "Error authenticating with password: %s\n",    ssh_get_error(my_ssh_session));
166.         ssh_disconnect(my_ssh_session);
167.         ssh_free(my_ssh_session);
168. exit(-1);
169. }
171.     show_remote_processes(my_ssh_session, command);
173.     fprintf(stderr, "alloc success\r\n");
174.     ssh_free(my_ssh_session);
175.     return 0;
176. }
178. int main(int argc, char *argv[])
179. {
180. int ret = 0;
181.     ret = ssh_connect_test(argv[1], argv[2]);
182. if (ret < 0) {
183.         fprintf(stderr, "connect error \r\n");
184.         return -1;
185. }
186.     return 0;
187. }

Makefile如下

1. CFLAGS    += -Werror -I/usr/local/include -L/usr/local/lib
3. CC        =gcc
4. LIBS    = -lssh
6. OBJS    += \
7.          1.o
8. TARGET    = target
9. all:$(OBJS)
10.     gcc $(CFLAGS) -o $(TARGET) $(OBJS) $(LIBS)
12. clean:
13.     rm -rf $(OBJS) $(TARGET)

然后直接make即可生成可执行文件target

然后执行效果如下

1. [liuqi@btg example_libssh]$ ./target 192.168.0.118 date
2. 2011年 06月 13日 星期一 14:07:04 CST
3. alloc success
4. [liuqi@btg example_libssh]$ ./target 192.168.0.118 who
5. liuqi tty1 2011-06-13 10:28 (:0)
6. liuqi pts/0 2011-06-13 10:29 (:0.0)
7. liuqi pts/1 2011-06-13 10:29 (:0.0)
8. liuqi pts/2 2011-06-13 13:54 (:0.0)
9. liuqi pts/3 2011-06-13 14:02 (:0.0)
10. alloc success
11. [liuqi@btg example_libssh]$