[Nut-upsuser] [NUT-upsuser] tcp-wrapper not found

[Charles Lepple]

On Mar 15, 2012, at 11:15 PM, Andrew Min Chang wrote:

> 1. upsd is a server, this "server" serves "client" but the common meaning of "net server". Which means upsd could not be seen by other device within the same LAN.

No, see below.

> 2. The real "net server" of UPS are drivers, such as usbhid-ups. The permission of access from network are done by tcp-wrapper.

Permissions can be controlled by tcp_wrappers, but the actual network server is upsd. (Drivers communicate with upsd over a Unix-domain socket, which is local to the master system.)

> 3. If a slave device B wants to connect to a master device A with UPS plugged into, it just needs to run upsd with a "LISTEN <IP of A>" in upsd.conf

Correct. (This is why the LISTEN directive is in upsd.conf, not ups.conf.)

Also, in most cases, tcp_wrappers can be replaced by kernel-level firewall rules.

-- 
Charles Lepple
clepple at gmail