Hands-On Network Programming with C

Server authentication

Once the SSH session is established, we can get the server's public key using the ssh_get_server_publickey() function. The following code illustrates this function call:

/*ssh_auth.c excerpt*/    ssh_key key;    if (ssh_get_server_publickey(ssh, &key) != SSH_OK) {        fprintf(stderr, "ssh_get_server_publickey() failed.\n%s\n",                ssh_get_error(ssh));        return -1;    }

It is often useful to obtain and display a hash of the server's SSH public key. Users can look at hashes and compare these to known keys. The libssh library provides the ssh_get_publickey_hash() function for this purpose.

The following code prints out an SHA1 hash of the public key obtained earlier:

/*ssh_auth.c excerpt*/    unsigned char *hash;    size_t hash_len; if (ssh_get_publickey_hash(key, ...