nmap（“Network Mapper”）是一款用于网络检测和安全审计的开源工具。它最初用于对大型网络进行快速扫描，但它对于单个主机的扫描也有很好的表现。
nmap 使用原始 IP 数据包来确定网络上可用的主机，这些主机的服务（包括应用程序名称和版本）、主机运行的操作系统（包括操作系统版本等信息）、正在使用的数据包过滤器或防火墙的类型，以及很多其它信息。
| # nmap -sV -p 22 localhost Starting Nmap 6.40 ( http://nmap.org ) at 2018-09-23 12:36 IST Nmap scan report for localhost (127.0.0.1) Host is up (0.000089s latency). Other addresses for localhost (not scanned): 127.0.0.1 PORT STATE SERVICE VERSION 22/tcp open ssh OpenSSH 7.4 (protocol 2.0) Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 1 IP address (1 host up) scanned in 0.44 seconds |
方法 6：使用 systemctl 命令
systemctl 是 systemd 系统的控制管理器和服务管理器。它取代了旧的 SysV 初始化系统管理，目前大多数现代 Linux 操作系统都采用了 systemd。
| # systemctl status sshd ● sshd.service - OpenSSH server daemon Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled) Active: active (running) since Sun 2018-09-23 02:08:56 EDT; 6h 11min ago Docs: man:sshd(8) man:sshd_config(5) Main PID: 11584 (sshd) CGroup: /system.slice/sshd.service └─11584 /usr/sbin/sshd -D Sep 23 02:08:56 vps.2daygeek.com systemd[1]: Starting OpenSSH server daemon... Sep 23 02:08:56 vps.2daygeek.com sshd[11584]: Server listening on 0.0.0.0 port 22. Sep 23 02:08:56 vps.2daygeek.com sshd[11584]: Server listening on :: port 22. Sep 23 02:08:56 vps.2daygeek.com systemd[1]: Started OpenSSH server daemon. Sep 23 02:09:15 vps.2daygeek.com sshd[11589]: Connection closed by 103.5.134.167 port 49899 [preauth] Sep 23 02:09:41 vps.2daygeek.com sshd[11592]: Accepted password for root from 103.5.134.167 port 49902 ssh2 |
以上输出的内容显示了最近一次启动 sshd 服务时 ssh 服务的监听端口。但它不会将最新日志更新到输出中。
| # systemctl status sshd ● sshd.service - OpenSSH server daemon Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled; vendor preset: enabled) Active: active (running) since Thu 2018-09-06 07:40:59 IST; 2 weeks 3 days ago Docs: man:sshd(8) man:sshd_config(5) Main PID: 1208 (sshd) CGroup: /system.slice/sshd.service ├─ 1208 /usr/sbin/sshd -D ├─23951 sshd: [accepted] └─23952 sshd: [net] Sep 23 12:50:36 vps.2daygeek.com sshd[23909]: Invalid user pi from 95.210.113.142 port 51666 Sep 23 12:50:36 vps.2daygeek.com sshd[23909]: input_userauth_request: invalid user pi [preauth] Sep 23 12:50:37 vps.2daygeek.com sshd[23911]: pam_unix(sshd:auth): check pass; user unknown Sep 23 12:50:37 vps.2daygeek.com sshd[23911]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=95.210.113.142 Sep 23 12:50:37 vps.2daygeek.com sshd[23909]: pam_unix(sshd:auth): check pass; user unknown Sep 23 12:50:37 vps.2daygeek.com sshd[23909]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=95.210.113.142 Sep 23 12:50:39 vps.2daygeek.com sshd[23911]: Failed password for invalid user pi from 95.210.113.142 port 51670 ssh2 Sep 23 12:50:39 vps.2daygeek.com sshd[23909]: Failed password for invalid user pi from 95.210.113.142 port 51666 ssh2 Sep 23 12:50:40 vps.2daygeek.com sshd[23911]: Connection closed by 95.210.113.142 port 51670 [preauth] Sep 23 12:50:40 vps.2daygeek.com sshd[23909]: Connection closed by 95.210.113.142 port 51666 [preauth] |
