Mac: Set Maximum Connection and Port Parameters

Maximum Connections Limit

The maximum number of connections limit refers to the limit of the maximum number of files (file descriptors) that the system can open, which is divided into global and per-process types:

Global

## The system's default maximum number of connections limit is 2147483647 
$ sysctl kern.maxfiles  
kern.maxfiles: 2147483647  
## Set the system's maximum number of connections from 49152 to 1048600 
$ sudo sysctl -w kern.maxfiles=1048600

Per-Process

# The default maximum number of connections per process is 61440 
$ sysctl kern.maxfilesperproc  
kern.maxfilesperproc: 61440  
# Set the per-process connection limit from 24576 to 1048576, the maximum number of connections per process must be less than or equal to the global connection limit 
$ sudo sysctl -w kern.maxfilesperproc=1048576

To make permanent changes, add the following content to /etc/sysctl.conf

kern.maxfiles=20480  
kern.maxfilesperproc=18000

This file may need to be created manually.

Ulimit Command

$ ulimit -n 4864 #### Display the maximum number of files that the current shell can open, the default value is: 4864, this value is always less than the value of kern.maxfilesperproc because a shell is a process. $ ulimit -n 1048576 ### Set the maximum number of files that the current shell can open to 1048576, this value cannot be greater than kern.maxfilesperproc, otherwise, it will prompt that the setting has failed.

Dynamic Port Range

➜  ~ sysctl net.inet.ip.portrange 
net.inet.ip.portrange.lowfirst: 1023 
net.inet.ip.portrange.lowlast: 600 
net.inet.ip.portrange.first: 49152 
net.inet.ip.portrange.last: 65535 
net.inet.ip.portrange.hifirst: 49152 
net.inet.ip.portrange.hilast: 65535 
net.inet.ip.portrange.ipport_allow_udp_port_exhaustion: 0

This indicates changing the starting address of the dynamic port to 32768; others are similar.

$ sysctl -w net.inet.ip.portrange.first=32768

launchd's Process Limitations

Get the current limits:

➜  ~ launchctl limit maxfiles 
 maxfiles    2048           unlimited

The output will be similar to this:
The former is the soft limit, and the latter is the hard limit.
Temporary modification it :

$ sudo launchctl limit maxfiles 65536 200000

To modify system-wide, create a plist file limit.maxfiles.plist in the folder /Library/LaunchDaemons and chmod the file permissions, and then load the new settings

<?xml version="1.0" encoding="UTF-8"?> 
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd"> 
<plist version="1.0"> 
  <dict> 
    <key>Label</key> 
    <string>limit.maxfiles</string> 
    <key>ProgramArguments</key> 
    <array> 
      <string>launchctl</string> 
      <string>limit</string> 
      <string>maxfiles</string> 
      <string>65536</string> 
      <string>200000</string> 
    </array> 
    <key>RunAtLoad</key> 
    <true/> 
    <key>ServiceIPC</key> 
    <false/> 
  </dict> 
</plist>

$ sudo chown root:hxzhouh /Library/LaunchDaemons/limit.maxfiles.plist  
$ sudo chmod 644 /Library/LaunchDaemons/limit.maxfiles.plist 
$ sudo launchctl load -w /Library/LaunchDaemons/limit.maxfiles.plist

Persisting Mac Configuration (Not Recommended)

sudo touch /etc/sysctl.conf;  
## Add the following content to the /etc/sysctl.conf file  
kern.maxfiles=1048600  
kern.maxfilesperproc=1048576  
net.inet.ip.portrange.first=49152  
net.inet.ip.portrange.last=65535  
## After adding, restart

The value of ulimit -n can be written in the .bashrc file.