linux 内核优化

groupadd -g 500 sysadm
groupadd -g 501 appadm

useradd -u 500 -g 500 sysctl -m
passwd sysctl

  Gf9Jk6Hvuh

useradd -u 501 -g 500 sysadm -m
passwd sysadm

  TAZk9TmpR6

useradd -u 502 -g 501 nflow -m
passwd nflow

  DPe2cU4Ggb

/home/sysctl/.ssh(mode 755)
/home/sysctl/.ssh/authorized_keys(mode 600)
/home/sysadm/.ssh(mode 755)
/home/sysadm/.ssh/authorized_keys(mode 600)
/home/nflow/.ssh(mode 755)
/home/nflow/.ssh/authorized_keys(mode 600)

/etc/ssh/sshd_config

  PasswordAuthentication no

/etc/ssh/sshd_config
RSAAuthentication yes

  PubkeyAuthentication yes

AuthorizedKeysFile .ssh/authorized_keys

/etc/ssh/sshd_config

  PermitRootLogin no

/etc/sudoers

  %sysadm         ALL=(ALL)       NOPASSWD: ALL

/etc/sysctl.conf
net.ipv4.tcp_syn_retries = 2
net.ipv4.tcp_abort_on_overflow = 1
net.ipv4.tcp_fin_timeout = 15
net.ipv4.tcp_keepalive_time = 1200
net.ipv4.tcp_keepalive_intvl = 30
net.ipv4.tcp_keepalive_probes = 3
net.ipv4.tcp_tw_reuse = 1
net.ipv4.ip_local_port_range = 10000 65000
net.ipv4.ip_forward = 0
net.ipv4.conf.default.accept_source_route = 0
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
net.core.netdev_max_backlog = 8192
net.core.somaxconn = 256
net.core.rmem_default = 262144
net.core.rmem_max = 4194304
net.core.wmem_default = 262144
net.core.wmem_max = 1048586
fs.file-max = 6553500
kernel.core_uses_pid = 1
kernel.shmmax = 2147483648
kernel.shmall = 1048576
kernel.shmmni = 4096
kernel.msgmnb = 65536
kernel.msgmax = 8192
kernel.perf_event_paranoid = 2
sysctl -p

/etc/security/limits.conf
root soft nofile 65535
root hard nofile 65535
soft nofile 65535
hard nofile 65535
/etc/security/limits.d/20-nproc.conf  
soft nproc 65536
  root soft nproc unlimited  

  /etc/profile  ulimit -SHn 65535  

  /etc/bashrc  [ "$PS1" = "s-v$ " ] && PS1="[33[0;32m]<u@h w>$ [33[0m]"  

  /etc/sudoers  Defaults    env_keep += "SSH_CLIENT"  

  /etc/bashrc  readonly export PROMPT_COMMAND='RETRN_VAL=$?;logger -p local6.debug "$(whoami) [$$]: ${SSH_CLIENT}: $(history 1 | sed "s/^[ ][0-9]+[ ]//" ) [$RETRN_VAL]"'  /etc/rsyslog.d/bash.conf  local6.*    /var/log/commands_history.log  systemctl restart rsyslog