<education for the IP impaired> So if a netwask of 255.255.255.240 is used and we enter an IP of xxx.xxx.xxx.45, does that mean that we will allow/deny the IP range of xxx.xxx.xxx.45-60 (16 addresses with one entry) ? </education for the IP impaired> Thanks, -----Original Message----- From: Peter Salvage <[EMAIL PROTECTED]> To: [EMAIL PROTECTED] <[EMAIL PROTECTED]> Date: Monday, November 01, 1999 4:22 PM Subject: Re: [IMail Forum] netmask for killing spam from ip range >The netmask is used to split a network of IP addresses into a collection >of smaller networks. A subnet mask is the mechanism that defines how the >host portion of the IP address is divided into subnetwork addresses and >local host address portions. IP addresses are represented by 4 sets of >octets: 123.456.789.123 thus in a /24 or as is commonly (and >erroneously) known, a Class C range of IP's, the netmask is >255.255.255.0 which means that 24 of the available 32 bits are set, >starting from most important to least important (left to right). > >In binary everything is either 1 or 0 right? So, look at the decimal >notation of a /24 again: 255.255.255.0. It's 4 octets, which means >there's 4 rows of 1's or 0's. We already know the first three are all >1's (maximum value of 255) and therefore by extension we know the LAST >octet must be all 0's (minimum value of 0). It's easy to work out too: > >128 64 32 16 8 4 2 1 > 1 1 1 1 1 1 1 1 > >The above is a decimal representation of an octet. The top row is the >value, the bottom row is the binary. So, if we want 255, we make them >all 1's. Add all the values in the top row up. Yep, we get 255. Get it? > >Now, the binary representation of that "Class C" we were talking about: > (255) (255) (255) (0) >11111111 11111111 11111111 00000000 > >Add up the 1's this time. Yep, there's 24...that's why we call it a /24 > ></class> > ></soapbox> > >/wiZZ > >----- Original Message ----- >From: Sales <[EMAIL PROTECTED]> >To: <[EMAIL PROTECTED]> >Sent: 02 November 1999 01:31 >Subject: Re: [IMail Forum] netmask for killing spam from ip range > > >> ooops that is what i meant. typo. >> thanks >> >> At 02:07 PM 11/1/99 -0500, you wrote: >> >If you're going to do something so radical.. at least contain the >damage... >> > >> >Try 38.29.63.0, 255.255.255.0 >> >and 38.29.64.0, 255.255.255.0 >> > >> >----- Original Message ----- >> >From: Sales <[EMAIL PROTECTED]> >> >To: <[EMAIL PROTECTED]> >> >Sent: Monday, November 01, 1999 1:56 PM >> >Subject: [IMail Forum] netmask for killing spam from ip range >> > >> > >> >> getting a lot of spam from these ips >> >> 38.29.64.243 >> >> 38.29.63 .84 >> >> 38.29.64.91 >> >> >> >> so i am just going to kill the whole range. >> >> 38.29.0.0 >> >> is the proper netmask 255.255.0.0 ? >> >> still haven't gotten the hang of the netmask yet. > >Please visit http://www.ipswitch.com/support/mailing-lists.html >to be removed from this list. > Please visit http://www.ipswitch.com/support/mailing-lists.html to be removed from this list.
