centos7 begin========================================================
没有ifconfig 	-> yum install net-tools
重启ssd服务		-> systemctl restart sshd.service
关闭selinux		-> vi /etc/sysconfig/selinux添加SELINUX=disabled
关闭防火墙		-> systemctl stop firewalld
				   systemctl disable firewalld.service
TCP连接数		-> vi /etc/security/limits.conf添加俩行
								* - nofile                   1024000
				-> vi /etc/pam.d/login添加一行
								session required /lib/security/pam_limits.so
				-> vi /etc/sysctl.conf添加一行
								net.ipv4.tcp_syncookies = 1
								net.ipv4.tcp_tw_reuse = 1
								net.ipv4.tcp_tw_recycle = 1
								net.ipv4.ip_local_port_range = 1024 65000
								net.ipv4.tcp_max_tw_buckets = 50000
								net.ipv4.tcp_fin_timeout = 10
								net.ipv4.tcp_keepalive_time = 30
								net.ipv4.tcp_window_scaling = 0
								net.ipv4.tcp_sack = 0
								fs.file-max = 65536
								net.ipv4.tcp_max_syn_backlog = 65536
								net.core.netdev_max_backlog = 32768
								net.core.somaxconn = 32768
								net.core.wmem_default = 8388608
								net.core.rmem_default = 8388608
								net.core.rmem_max = 16777216
								net.core.wmem_max = 16777216
								net.ipv4.tcp_timestamps = 0
								net.ipv4.tcp_synack_retries = 2
								net.ipv4.tcp_syn_retries = 2
								net.ipv4.tcp_max_syn_backlog = 10240
								net.core.netdev_max_backlog = 51200
								net.ipv4.tcp_keepalive_probes = 5
								net.ipv4.tcp_keepalive_intvl = 15
								net.ipv4.tcp_retries2 = 5
								net.ipv4.tcp_orphan_retries = 3
								net.ipv4.tcp_reordering = 5
								net.ipv4.tcp_retrans_collapse = 0