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Accepted
King David
Asked: 2024-02-25 23:10:37 +0800 CST

RHEL + how to know the limit of concurrent connections number per port?

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how to know the number of concurrent connections per port on RHEL 7.x machines

for instance, let say we connect to port 9080 with XXXX concurrent connections.

wget  http://server_mngmnt.jupiter.com:9080 &
wget  http://server_mngmnt.jupiter.com:9080 &
wget  http://server_mngmnt.jupiter.com:9080 &
wget  http://server_mngmnt.jupiter.com:9080 &
wget  http://server_mngmnt.jupiter.com:9080 &
.
.
.

second - what could be the results of huge concurrent connections to port 9080 ?

from my machine

more /etc/security/limits.conf


# End of file
* soft nofile 25000
* hard nofile 25000

sysctl -n fs.file-max
500000

ulimit -n
63536
linux

1 Answers

  1. Best Answer

    The upper limit of how many connections a listener can support depends on the lowest limit imposed by:

    • the application that is listening
    • the limits the OS sets for the application creating the listener with regards to the number of open file descriptors (ulimit -n ) that can be per session, in a systemd service unit file, /etc/security/limits.conf etc.
    • the limits the OS / Linux kernel sets for the number of open file descriptors for all applications combined sysctl -n fs.file-max
    • the amount of avialable memory

    and possibly others.

    The number connections a client can make will be similarly restricted by the number of open file descriptors, available memory and the number of available ephemeral ports.

    • 2