Regarding Qmail Relay and Spam

[faris]

This is odd...

I entered 127.0.0.* in the whitelist and Plesk came back to display 127.0.0.0/8 (i.e. the default)

On the other hand, if I enter 127.0.0.0/255.255.255.0 I get 127.0.0.0/24 (which is what I'd expect if the 255.255.255.0 is a reverse netmask sort of thing).

I wonder about this. Is the /8 shown when I enter 127.0.0.* a reverse netmask or something strange like that (32-8=24)? But if it is, then surely instead of /24 when I enter 127.0.0.0/255.255.255.0 I should get 127.0.0.0/8 as well.

Oh...after all that. It is a bug in 7.5 at least. Entering 127.0.*.* also gives 127.0.0..0/8.

Very confusing! I'm not going to abandon this post in case this is useful for anyone else trying to use the * option for whitelisting.

 

[phatpixel]

The number after the slash represents the netmask, or in this case, number of bits that are set in the netmask.

For example, 255.255.255.0 is the decimal way of writing 11111111.11111111.11111111.00000000 in binary. You'll notice that there are 24 bits set in this netmask, hence /24.

Similarly, 255.0.0.0 is the same as 11111111.00000000.00000000.00000000 which is the same as /8.

I won't go into more detail about netmasks because this is the point that things can start getting confusing But hopefully that gives you a better [albeit brief] understanding of the notation.

 

[faris]

Thanks!

Faris.

 

[Dan Thompson]

My guess is when you put in 127.0.0.* since you didn't give it a netmask, Plesk assumes a netmask of /8. It means any address that starts with 127., not 127.0.0.* like you put in. Really the only address you should have in there would be the 127.0.0.1/32 loopback address and maybe any other servers on your network that you'd like to be able to relay.

 

[nullsystems]

Thanks guys, Dan you really helped towards this forum.

is there any way to get admins to put this in a sticky? It seems to be really popular and I know its deffinatly helped alot of people and server owners!

Admins, help out !