As an informational post only, your IP hasn’t changed the last six months.
Wow! Thanks.
Doesn’t IP restriction create delays? I know Host files do when they are too long. The problem lies in the simpleminded searches that are used, usually serial and checking the entire addresses in the list, instead of b-trieve and byte-by-byte exiting. As the banned list or Host list grows the delays grow, so you are advised to regularly purge and start over with minimal lists.
You have it correct: The addition of these rules always incurs some overhead, which can be mitigated by intelligent software design (keeping the list of blocked IP addresses/ranges sorted and doing intelligent lookups based on good search algorithms) but never dropped to zero. However, software performance is a complex issue and the only way to know what’s slowing you down is profiling, profiling, and profiling.
The 192.168 tells you that it’s a private class C network. 47 is 0x2F. If someone elects to use a subnet mask of 0xfffffff0, 192.168.1.47 would be the broadcast address of subnet 192.168.1.32.
So, if you see that address used as a host address, you know the source network is not using a 4-bit subnetting of a class C address. This would seem to be a marvelously useless piece of information, but it’s the only factual answer to your question that I can imagine.
You already have and answer from samclem that you keep the same one for a long time but I had a question. Do you have a router connected to the cable? I have one at home and the router gets assigned an IP by the ISP and then my computers get assigned a 192.168.1.xxx IP locally. It is the IP address on the WAN side (cable side) that the world and samclem sees. The reason I bring this up is that while the computer I use gets turned on and off the router stays on 24/7 and there is not a good point at which the IP address is available to be reassigned.
Some cable modems change IP numbers when the power goes off, and most change every few months when the ISP’s computer is down or reset. In addition, you can ask them to reset it, which you might have to do if you find a spammer has gotten past your firewall - when that happens all your email will be coming back “rejected by recipient as suspected spam based on IP number”
Ok, this brings up something I guess I sort of knew, but haven’t given much thought to. I said in a previous post that 255 as the last byte of the address is reserved for broadcast, but it’s actually the highest address on the subnet, isn’t it?
None of the octets can go above 255 due to the restriction that binary numbering imposes on the set. 128, 64, 32, 16, 8, 4, 2, 1 add up to 255. 255 is the highest possible octet value in any IP. Am I misunderstanding your point?
Yes the highest address on the subnet is reserved for the broadcast address. That doesn’t necessarily mean that the last byte of a host address can’t be 255, though. E.g. in a network 192.160.0.0/16, a host address such as 192.168.3.255 would be valid, because the broadcast address would be 192.168.255.255 . On a /24 network, the address with 255 in the final octet would be the broadcast address.
(Personally I think these things are more easily grasped if you consider IP addresses as long binary numbers. Decimal notation requires lots of mental arithmetic.)
I wasn’t proposing that the broadcast might have a higher value than 255 in the last byte (as you point out, an 8 bit byte can’t have a value higher than 255). I meant to say that it might be a lower value than 255, depending on your subnet mask.
If you have a subnet mask of 255.255.255.0, then the highest address does end with 255. But if you use a subnet mask that makes 45 the highest possible value for the last byte of the addresses on your subnet, then the broadcast address will end with 45.
It’s just that in all the private networks I’ve set up, I have used the 255.255.255.0 subnet mask, I just haven’t needed to do otherwise in the relatively small networks I work with. So I’m just used to thinking of 255 as the broadcast address, when in reality it isn’t necessarily 255, but whatever the highest possible address is.
Thank you, after thinking about it, I thought that must be the case, but wasn’t positive. And thanks for bringing up the /16 example, again just because I don’t work with them I hadn’t considered it, but it makes perfect sense.
Absolutely. I’ve always thought of the numbers as bytes, which just string together into a 32 or 48 bit address or bit mask.
So that would be a mask ending in 11010010? Yikes! (the mask bits have to be contiguous)
Oops, I just picked 45 as random example number in the range that wasn’t 255. I didn’t even think about the resulting bit mask. :smack: