# tcp\_connections

**URL:** <https://community.netdata.cloud/t/tcp-connections/2183>\
**Category:** Alerts\
**Created:** [November 20, 2021, 5:51pm UTC](https://community.netdata.cloud/t/tcp-connections/2183 "2021-11-20T17:51:50Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ancairon](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.netdata.cloud/ancairon/32/1001_2.png) [@Ancairon](https://community.netdata.cloud/u/Ancairon)\
**Post date:** [November 20, 2021, 5:51pm UTC](https://community.netdata.cloud/t/tcp-connections/2183/1 "2021-11-20T17:51:50Z")

</div>

# tcp\_connections

## OS: Linux

This alert presents the percentage of used IPv4 TCP connections. If you receive it, it is an indication of high IPv4 TCP connections utilization.

If this value is 100% then the system is no longer able to establish new TCP connections.

- This alert is raised to a state of warning when the percentage of used IPv4 TCP connections is  
greater than 80% and less than 90%.
- If the percentage of used IPv4 TCP connections exceeds 90%, then the alert gets raised to critical.

> **TCP Connections Alarm Settings**
>
> Inside the [tcp\_conn.conf](https://github.com/netdata/netdata/blob/master/health/health.d/tcp_conn.conf), on the `calc:` line, there is this block of code:  
> `(${tcp_max_connections} > 0) ? ( ${connections} * 100 / ${tcp_max_connections} ) : 0`
> 
> - That line of code will calculate the value of `$this` in the following lines.
> - Essentially, if the max connections are not dynamic, and there is a limit, then we calculate the  
> percentage of used IPv4 TCP connections. Otherwise, we have a dynamic threshold  
> _(so `${tcp_max_connections}` may be nan or -1)_, which in this case the alert and `$this` will  
> always be zero.