35 Upgrade notes for 3.0.25

Removing stale agent connections

Previously, if a system had devices with dynamically changing paths or if a device got manually removed, Zabbix agent would not release them and would keep the connection resulting in collector overfilling. Now Zabbix agent will terminate "stale" device connections if the values of corresponding items are not accessed for more than 3 hours. Note that the corresponding items (vfs.dev.read[], vfs.dev.write[]), if having the update interval longer than 3 hours, will now always return '0'.

Frontend changes

• Frontend no longer enforces HTTP Strict Transport Security (HSTS) policy, introduced in 3.0.13. To protect Zabbix frontend against protocol downgrade attacks, it is recommended to enable HSTS policy on the webserver.