出處：未驗證）
安裝centos 7 系統之後要做的幾件事
#修改主機名
hostnamectl --static set-hostname xd-1
vim /etc/hosts
127.0.0.1 xd-1
x.x.x.x xd-1
#下面是使用iptables
systemctl stop firewalld.service
systemctl disable firewalld.service
yum -y install iptables-services
adduser wwwad
passwd wwwad
vim /etc/ssh/sshd_config
port 10999
permitrootlogin no
systemctl restart sshd.services
visudo
wwwad all = (root) nopasswd: wwwad
cmnd_alias wwwad = all
#加大開啟檔案數的限制（open files）
ulimit -n
ulimit -a
vi /etc/security/limits.conf
最後新增
* soft nofile 1024000
* hard nofile 1024000
hive - nofile 1024000
hive - nproc 1024000
使用者程序限制
[root@hequan ~]# sed -i 's#4096#65535#g' /etc/security/limits.d/20-nproc.conf #加大普通使用者限制 也可以改為unlimited
[root@hequan ~]# egrep -v "^$|^#" /etc/security/limits.d/20-nproc.conf
* soft nproc 65535
root soft nproc unlimited
reboot
vim /etc/sysctl.conf
#ctcdn系統優化引數
#關閉ipv6
net.ipv6.conf.all.disable_ipv6 = 1
net.ipv6.conf.default.disable_ipv6 = 1
#決定檢查過期多久鄰居條目
net.ipv4.neigh.default.gc_stale_time=120
#使用arp_announce / arp_ignore解決arp對映問題
net.ipv4.conf.default.arp_announce = 2
net.ipv4.conf.all.arp_announce=2
net.ipv4.conf.lo.arp_announce=2
# 避免放大攻擊
net.ipv4.icmp_echo_ignore_broadcasts = 1
# 開啟惡意icmp錯誤訊息保護
net.ipv4.icmp_ignore_bogus_error_responses = 1
#關閉路由**
net.ipv4.ip_forward = 0
net.ipv4.conf.all.send_redirects = 0
net.ipv4.conf.default.send_redirects = 0
#開啟反向路徑過濾
net.ipv4.conf.all.rp_filter = 1
net.ipv4.conf.default.rp_filter = 1
#處理無源路由的包
net.ipv4.conf.all.accept_source_route = 0
net.ipv4.conf.default.accept_source_route = 0
#關閉sysrq功能
kernel.sysrq = 0
#core檔名中新增pid作為副檔名
kernel.core_uses_pid = 1
# 開啟syn洪水攻擊保護
net.ipv4.tcp_syncookies = 1
#修改訊息佇列長度
kernel.msgmnb = 65536
kernel.msgmax = 65536
#設定最大記憶體共享段大小bytes
kernel.shmmax = 68719476736
kernel.shmall = 4294967296
#timewait的數量，預設180000
net.ipv4.tcp_max_tw_buckets = 6000
net.ipv4.tcp_sack = 1
net.ipv4.tcp_window_scaling = 1
net.ipv4.tcp_rmem = 4096 87380 4194304
net.ipv4.tcp_wmem = 4096 16384 4194304
net.core.wmem_default = 8388608
net.core.rmem_default = 8388608
net.core.rmem_max = 16777216
net.core.wmem_max = 16777216
#每個網路介面接收資料報的速率比核心處理這些包的速率快時，允許送到佇列的資料報的最大數目
net.core.netdev_max_backlog = 262144
#限制僅僅是為了防止簡單的dos 攻擊
net.ipv4.tcp_max_orphans = 3276800
#未收到客戶端確認資訊的連線請求的最大值
net.ipv4.tcp_max_syn_backlog = 262144
net.ipv4.tcp_timestamps = 0
#核心放棄建立連線之前傳送synack 包的數量
net.ipv4.tcp_synack_retries = 1
#核心放棄建立連線之前傳送syn 包的數量
net.ipv4.tcp_syn_retries = 1
#啟用timewait 快速**
net.ipv4.tcp_tw_recycle = 1
#開啟重用。允許將time-wait sockets 重新用於新的tcp 連線
net.ipv4.tcp_tw_reuse = 1
net.ipv4.tcp_mem = 94500000 915000000 927000000
net.ipv4.tcp_fin_timeout = 1
#當keepalive 起用的時候，tcp 傳送keepalive 訊息的頻度。預設是2 小時
net.ipv4.tcp_keepalive_time = 1800
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_keepalive_intvl = 15
#允許系統開啟的埠範圍
net.ipv4.ip_local_port_range = 1024 65000
#修改防火牆表大小，預設65536
net.netfilter.nf_conntrack_max=655350
net.netfilter.nf_conntrack_tcp_timeout_established=1200
# 確保無人能修改路由表
net.ipv4.conf.all.accept_redirects = 0
net.ipv4.conf.default.accept_redirects = 0
net.ipv4.conf.all.secure_redirects = 0
net.ipv4.conf.default.secure_redirects = 0
sysctl -p
# 同步時間
ntpdate time.nist.gov
hwclock -w #先同步一遍時間到硬體時間
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