Date: Sun, 9 Sep 2001 14:06:45 -0700 From: "Ted Mittelstaedt" <tedm@toybox.placo.com> To: "ann kok" <annkok2001@yahoo.com>, <freebsd-questions@FreeBSD.ORG> Subject: RE: cable modem Message-ID: <001601c13973$5549b280$1401a8c0@tedm.placo.com> In-Reply-To: <20010909184733.69519.qmail@web20108.mail.yahoo.com>
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With IP numbering, one way to roughly divide it up is to classify IP addresses as either "public" or "private". Sometimes the terms "legal" and "illegal" are used. Public numbers are IP numbers that are routable on the general Internet. For example if you have the public number 200.100.100.1 then from any point on the Internet that is not your network I can send traffic to that address and that traffic will terminate at your machine. Private numbers are IP numbers that are not routable on the Internet. For example if you have a system with an IP number 192.168.1.1 then from any point on the Internet that is not your network I can attempt to send traffic to that address but my traffic will terminate almost immediately, many, many hops away from you. This allows many many networks to use the same IP numbers internally, you can use 192.168.1.1, someone else can use 192.168.1.1, etc. etc. Thus it makes sense that I cannot send traffic to you because there is no way to tell the Internet routers that my traffic to 192.168.1.1 is supposed to go to you, and not someone else running 192.168.1.1 There are ranges of IP numbers that are specifically set aside as private numbers, they are detailed in RFC1918. Generally, the networking hardware that's used to allow people running those numbers to access hosts on the Internet is either a Network Address Translator, or a Proxy Server. It is also possible to use public routable numbers as private numbers, but the same restrictions apply in that you have to use either a NAT or a Proxy server. Also an additional problem with doing that is that if you use the IP numbers assigned to someone elses computers, you will have problems accessing their network. This is why RFC1918 sets aside numbers. Ted Mittelstaedt tedm@toybox.placo.com Author of: The FreeBSD Corporate Networker's Guide Book website: http://www.freebsd-corp-net-guide.com >-----Original Message----- >From: ann kok [mailto:annkok2001@yahoo.com] >Sent: Sunday, September 09, 2001 11:48 AM >To: Ted Mittelstaedt; freebsd-questions@FreeBSD.ORG >Subject: RE: cable modem > > > >Dear Ted Mittelstaedt > >I couldn't catch your meaning.\! >Could you explain to me in detail? > >Thanks > >--- Ted Mittelstaedt <tedm@toybox.placo.com> wrote: >> Do you know for a fact that the IP number they are >> assigning is a public >> number? It could be that she is getting a private >> number that's behind >> a translator. >> >> Ted Mittelstaedt >> tedm@toybox.placo.com >> Author of: The FreeBSD >> Corporate Networker's Guide >> Book website: >> http://www.freebsd-corp-net-guide.com >> >> >> >-----Original Message----- >> >From: owner-freebsd-questions@FreeBSD.ORG >> >[mailto:owner-freebsd-questions@FreeBSD.ORG]On >> Behalf Of ann kok >> >Sent: Saturday, September 08, 2001 8:33 PM >> >To: freebsd-questions@FreeBSD.ORG >> >Subject: cable modem >> > >> > >> >Dear all >> > >> >I am wandering why cable modem provider can have >> >static ip to her customer. >> > >> >At least one IP for one house. In addition, IP is >> not >> >sufficent in the internet now. How they can do >> that? >> > >> >Thank you >> > >> > >> >__________________________________________________ >> >Do You Yahoo!? >> >Get email alerts & NEW webcam video instant >> messaging with Yahoo! Messenger >> >http://im.yahoo.com >> > >> >To Unsubscribe: send mail to majordomo@FreeBSD.org >> >with "unsubscribe freebsd-questions" in the body of >> the message >> > > > >__________________________________________________ >Do You Yahoo!? >Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger >http://im.yahoo.com > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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