Linux parameter optimization

Port Range

View available port range

cat /proc/sys/net/ipv4/ip_local_port_range
32768   60999

Modify the port range available

# 临时修改
echo 1024 65000 > /proc/sys/net/ipv4/ip_local_port_range
# 永久修改：在/etc/sysctl.conf中添加如下信息
net.ipv4.ip_local_port_range = 1024 65535
# 然后生效一下
sysctl -p

TIME_WAIT processing

Pressure measurement process, TCP connection active close side will be a lot of TIME_WAIT state, resulting in problems such as inadequate port
may be configured to
refer to

# 同样，在/etc/sysctl.conf中添加如下信息，最后使用sysctl -p生效一下

# 表示开启SYN cookies。当出现SYN等待队列溢出时，启用cookies来处理，可防范少量SYN攻击，默认为0，表示关闭
net.ipv4.tcp_syncookies = 1
# 表示开启重用。允许将TIME-WAIT sockets重新用于新的TCP连接，默认为0，表示关闭；
net.ipv4.tcp_tw_reuse = 1
# 表示开启TCP连接中TIME-WAIT sockets的快速回收，默认为0，表示关闭
net.ipv4.tcp_tw_recycle = 1
# 修改系統默认的 TIMEOUT 时间
net.ipv4.tcp_fin_timeout = 30

ulimit configuration

Displays all current resource limits

ulimit -a
core file size          (blocks, -c) 0
data seg size           (kbytes, -d) unlimited
scheduling priority             (-e) 0
file size               (blocks, -f) unlimited
pending signals                 (-i) 63445
max locked memory       (kbytes, -l) 64
max memory size         (kbytes, -m) unlimited
open files                      (-n) 1024
pipe size            (512 bytes, -p) 8
POSIX message queues     (bytes, -q) 819200
real-time priority              (-r) 0
stack size              (kbytes, -s) 8192
cpu time               (seconds, -t) unlimited
max user processes              (-u) 63445
virtual memory          (kbytes, -v) unlimited
file locks                      (-x) unlimited

The above parameters can be modified directly, but only take effect in the current Session Session and its derivatives, is not recommended
for permanent modifications in /etc/security/limits.conf, the format:
<Domain> <of the type> <Item> <value>
(Description of reference notes section in limits.conf)
after modification to log in again to take effect

* soft core unlimited
* hard core unlimited

Boot from the start

Add the startup command to the /etc/rc.d/rc.local

*          soft    nproc     unlimited
*          hard    nproc     unlimited

*          soft    nofile    1024000
*          hard    nofile    1024000

## 当前用户最大登录数
## max number of logins for this user
* soft maxlogins 100
* hard maxlogins 100

## 系统最大登录用户数
## max number of logins on the system
* soft maxsyslogins 100
* hard maxsyslogins 100

Can not allocate memory handling problem

Check the maximum number of processes sysctl kernel.pid_max
view the number of processesps -eLf | wc -l

Confirm the number of processes is full

Temporary modifications:
echo 1000000 > /proc/sys/kernel/pid_max

Permanent:

echo "kernel.pid_max=1000000 " >> /etc/sysctl.conf
sysctl -p