[Nut-upsdev] Remote Monitoring From Web

[Arjen de Korte]

Citeren Eric Wilde <ewilde at bsmdevelopment.com>:

> When I use LISTEN, I see an error message about upsd not listening on
> port 3493.  For example:
>
>   LISTEN 192.168.1.1 3493
>
> gives
>
>   not listening on 192.168.1.1 port 3493

Most likely, the port is already in use. What does 'netstat' say here.

> Any attempts to monitor this system's UPS from the Web UI is then met
> with:
>
>   error: Connection failure: Connection refused
>
> Did anybody think this through before breaking it?

Sure. And if you would have read the archives, you would also know why we did.

> Apart from the fact
> that LISTEN seems to be broken, how is one supposed to accept connections
> from part of a network (e.g. 192.168.1.1/24) or reject connections from
> a specific machine or range of machines.

Use a firewall and read the chapter on ACCESS CONTROL in 'man 8 upsd'.  
Together they will give you the same level of granularity.

> LISTEN doesn't come even close
> to the flexibility of ACL/ACCEPT.

There is nothing you can do with the previous ACL/ACCEPT mechanism  
that can't be done through LISTEN, tcp-wrappers and a firewall. And  
instead of giving you a false sense of security of the previous  
mechanism, this will actually work against attacks on your upsd server.

Best regards, Arjen
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