Mar 2 02:34:02 freetalker3 sshd[28436]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:08 freetalker3 sshd[28439]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:13 freetalker3 sshd[28442]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:19 freetalker3 sshd[28445]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:24 freetalker3 sshd[28448]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:30 freetalker3 sshd[28451]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:35 freetalker3 sshd[28454]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:41 freetalker3 sshd[28457]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:46 freetalker3 sshd[28460]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:52 freetalker3 sshd[28463]: Did not receive identification string from 211.110.33.50 Mar 2 02:34:57 freetalker3 sshd[28466]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:03 freetalker3 sshd[28469]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:08 freetalker3 sshd[28472]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:14 freetalker3 sshd[28475]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:20 freetalker3 sshd[28478]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:25 freetalker3 sshd[28481]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:31 freetalker3 sshd[28484]: Did not receive identification string from 211.110.33.50 Mar 2 02:35:36 freetalker3 sshd[28488]: Did not receive identification string from 211.110.33.50 我的/var/log/auth.log中充满了这些消息，每6秒发送一次垃圾消息。 我的服务器是在VPS和IP似乎是一个内部IP。 这个问题的原因是什么？
有些歹徒（惊喜！）在ssh上敲击试图find一个用户名/密码组合，让他们进入系统。 也许从一些僵尸networking做同样的事情，谁知道还有多less其他毫无戒心的受害者。
安装类似fail2ban或DenyHosts （其中一些应该可用于任何Linux发行版），或者设置本地防火墙来限制SSH连接尝试。 改变SSH端口使得愚蠢的蛮力尝试失败，但它也使合法使用失败。
实际上，这是来自我的托pipe服务提供商 – 他们每隔6秒发送一次我的VPS垃圾邮件，以在我的Web控制台上显示我的服务器状态。 我的服务器显示为活动，如果我的sshd回答他们。
我刚刚安装了OpenVPN，只允许通过SSH – 所以，根据我的供应商，我的服务器拥有100％的停机时间。
这很可能是一个通信的keepalive（validation服务器正在响应）。 设备。
当有人试图访问但是没有完成这些步骤时，这些消息被SSH抛出。 例如，如果NMS正在检查端口ssh 22是否启动，它只会尝试在端口22上连接，如果连接成功，则挂起，在这种情况下，SSH报告相同。
所以这是因为SSH端口扫描。
尝试在sshd_config中将ssh端口从22更改为另一个：
sudo nano /etc/ssh/sshd_config
如果不停止消息，问题也可能是由以下原因造成的： Freebpx在/ var / log / secure日志文件中导致sshd错误，或者在Ubuntu论坛的auth.log中看到“没有收到标识string”的讨论。
如果您想知道谁的端口扫描或尝试在您的机器上进行身份validation，请检查：
# whois 211.110.33.50 # KOREAN(UTF8) 조회하신 IPv4주소는 한국인터넷진흥원으로부터 아래의 관리대행자에게 할당되었으며, 할당 정보는 다음과 같습니다. [ 네트워크 할당 정보 ] IPv4주소 : 211.110.0.0 - 211.110.239.255 (/17+/18+/19+/20)
等等