Proton/docs/ICMP_ECHO.md

# ICMP ECHO requests (ping)

Some games rely on ICMP ECHO requests to detect network connectivity,
or to measure connection ping.

Proton supports sending ICMP ECHO requests using RAW sockets or DGRAM
ICMP sockets, but the former requires elevated priviledges, and the
latter may also be disabled by default.

DGRAM ICMP sockets can be enabled for a given set of user groups by
running the following command, and will stay enabled until next reboot:

```
sudo sysctl -w net.ipv4.ping_group_range="<low> <high>"
```

Where <low> (resp <high>) is lower bound (resp higher) of the user
groups which will be allowed to create such sockets. It is possible to
enable them for any group by using "0 4294967295".

In order for the configuration to be persistent, it is possible to add
the following line to `/etc/sysctl.conf` (or a file in `/etc/sysctl.d`):

```
net.ipv4.ping_group_range="<low> <high>"
```