add ping README

README.md

@@ -20,7 +20,7 @@ tar zcvf categraf.tar.gz categraf conf
 
 - []ntp
 - [x]exec
-- []ping
+- [x]ping
 - []net_response
 - []http_response
 - []scrape

inputs/ping/README.md

@@ -0,0 +1,56 @@
+### File Limit
+
+```sh
+systemctl edit categraf
+```
+
+Increase the number of open files:
+
+```ini
+[Service]
+LimitNOFILE=8192
+```
+
+Restart Categraf:
+
+```sh
+systemctl restart categraf
+```
+
+### Linux Permissions
+
+On most systems, ping requires `CAP_NET_RAW` capabilities or for Categraf to be run as root.
+
+With systemd:
+
+```sh
+systemctl edit categraf
+```
+
+```ini
+[Service]
+CapabilityBoundingSet=CAP_NET_RAW
+AmbientCapabilities=CAP_NET_RAW
+```
+
+```sh
+systemctl restart categraf
+```
+
+Without systemd:
+
+```sh
+setcap cap_net_raw=eip /usr/bin/categraf
+```
+
+Reference [`man 7 capabilities`][man 7 capabilities] for more information about
+setting capabilities.
+
+[man 7 capabilities]: http://man7.org/linux/man-pages/man7/capabilities.7.html
+
+### Other OS Permissions
+
+When using `method = "native"`, you will need permissions similar to the executable ping program for your OS.
+
+
+