上次还好好的，今天突然就sshd无法登录，提示内容 Putty Fatal Error Network error connection timed out，但是ftp可以登录（端口2100），网站可以打开（端口80）。
Linode VPS，使用sshd突然怎么都登录不上！
然后进入linode 的网页版本，查看 sshd的状态，显示的是咋监听2277端口（我修改过sshd端口）
[root@flxx basic]# systemctl status sshd -l
sshd.service - OpenSSH server daemon
Loaded: loaded (/usr/lib/systemd/system/sshd.service; enabled)
Active: active (running) since Thu 2015-02-12 21:46:23 CST; 38min ago
Process: 2669 ExecStartPre=/usr/sbin/sshd-keygen (code=exited, status=0/SUCCESS)
Main PID: 2672 (sshd)
CGroup: /system.slice/sshd.service
└─2672 /usr/sbin/sshd -D
Feb 12 21:46:23 flxx systemd[1]: Started OpenSSH server daemon.
Feb 12 21:46:23 flxx sshd[2672]: Server listening on 0.0.0.0 port 2277.
Feb 12 21:46:23 flxx sshd[2672]: Server listening on :: port 2277.
Feb 12 21:53:45 flxx sshd[2753]: Bad protocol version identification '' from 192.0.83.252
Feb 12 21:54:09 flxx sshd[2755]: Bad protocol version identification '' from 192.0.83.252
Feb 12 22:02:38 flxx sshd[2789]: Bad protocol version identification '\377\364\377\375\006\377\364\377\375\006' f
rom 192.0.83.252
查看端口号占用情况，确实是sshd在使用：
[root@flxx basic]# lsof -i:2277
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
sshd 2672 root 3u IPv4 6903 0t0 TCP *:mmcals (LISTEN)
sshd 2672 root 4u IPv6 6914 0t0 TCP *:mmcals (LISTEN)
[root@flxx basic]#
现在无法登录sshd，之前一直好好的，现在突然无法登录sshd，通过putty也不行，通过cuteFtp的SFTP也不行。但是机子里面的FTP（vsftpd）可以登录，且网站也可以访问。
最后一次的操作安装了mongodb redis gcc，然后退出了，没有再操作，今天在登录就提示无法连接。
Feb 09 09:44:04 Installed: boost-system-1.53.0-18.el7.x86_64
Feb 09 09:44:04 Installed: boost-thread-1.53.0-18.el7.x86_64
Feb 09 09:44:04 Installed: boost-filesystem-1.53.0-18.el7.x86_64
Feb 09 09:44:04 Installed: libunwind-1.1-3.el7.x86_64
Feb 09 09:44:04 Installed: gperftools-libs-2.1-1.el7.x86_64
Feb 09 09:44:05 Installed: 1:v8-3.14.5.10-14.el7.x86_64
Feb 09 09:44:05 Installed: boost-program-options-1.53.0-18.el7.x86_64
Feb 09 09:44:16 Installed: mongodb-2.6.5-2.el7.x86_64
Feb 09 09:45:14 Installed: jemalloc-3.6.0-1.el7.x86_64
Feb 09 09:45:15 Installed: redis-2.8.14-2.el7.x86_64
Feb 09 09:46:21 Installed: libevent-2.0.21-4.el7.x86_64
Feb 09 09:46:21 Installed: memcached-1.4.15-9.el7.x86_64
Feb 09 09:49:37 Updated: glibc-common-2.17-55.el7_0.5.x86_64
Feb 09 09:49:38 Updated: glibc-2.17-55.el7_0.5.x86_64
Feb 09 09:49:38 Installed: mpfr-3.1.1-4.el7.x86_64
Feb 09 09:49:39 Installed: libmpc-1.0.1-3.el7.x86_64
Feb 09 09:49:39 Installed: cpp-4.8.2-16.2.el7_0.x86_64
Feb 09 09:49:40 Installed: kernel-headers-3.10.0-123.20.1.el7.x86_64
Feb 09 09:49:40 Installed: glibc-headers-2.17-55.el7_0.5.x86_64
Feb 09 09:49:41 Installed: glibc-devel-2.17-55.el7_0.5.x86_64
Feb 09 09:49:44 Installed: gcc-4.8.2-16.2.el7_0.x86_64
奇怪
我把sshd端口修改为 其他的，比如22 或者2271 可以登录，但使用2277这个端口是怎么都登录不了
试试关闭防火墙 systemctl stop firewalld