I have a Mac with OS X on a cablemodem (connected through a wifi network and
a Linksys router). Comcast hands out a dynamic IP address. What I want is to
be able to get my files when I'm on the road (by running an FTP or other
file sharing server on my computer). The thing is, in order to get to my
machine, I need to know the IP address when I'm away, but it changes all the
time because of the dynamic addressing. Is there anything I'm missing? Is it
possible to find my computer from the internet, given that it's behind a
cablemodem? I did have one idea: I could write some code to run in
background and have the computer dump its IP address to a file on a known
FTP site every few hours. That way, all I'd have to do from the remote
location is go to the FTP site, open the data file, read the current IP
address, and use that to find my machine. Would that work? Is there any
software which does this already (before I reinvent the wheel)? The other
thing which is confusing me is: my computer is behind a Linksys wireless
router, which gets its IP address from the cablemodem, but then hands out a
"fake" (LAN) address to my machine. So, how do I actually get an address
which can be used from the outside world to reach my machine? I am
constantly being warned about the necessity for firewalls to protect from
hackers, so I guess someone knows how to reach my computer - it must be
possible! So, if anyone has any thoughts on this issue, please cc: your
post to mlevin77@comcast.net. Thank you!!

Mike

--

Mike Levin
mlevin77@comcast.net

check out such services as http://www.dyndns.org/services/dyndns/


"Michael Levin" <mlevin77@comcast.net> wrote in message
news:BBE40897.B8D%mlevin77@comcast.net...
> I have a Mac with OS X on a cablemodem (connected through a wifi network
and
> a Linksys router). Comcast hands out a dynamic IP address. What I want is
to
> be able to get my files when I'm on the road (by running an FTP or other
> file sharing server on my computer). The thing is, in order to get to my
> machine, I need to know the IP address when I'm away, but it changes all
the
> time because of the dynamic addressing. Is there anything I'm missing? Is
it
> possible to find my computer from the internet, given that it's behind a
> cablemodem? I did have one idea: I could write some code to run in
> background and have the computer dump its IP address to a file on a known
> FTP site every few hours. That way, all I'd have to do from the remote
> location is go to the FTP site, open the data file, read the current IP
> address, and use that to find my machine. Would that work? Is there any
> software which does this already (before I reinvent the wheel)? The other
> thing which is confusing me is: my computer is behind a Linksys wireless
> router, which gets its IP address from the cablemodem, but then hands out
a
> "fake" (LAN) address to my machine. So, how do I actually get an address
> which can be used from the outside world to reach my machine? I am
> constantly being warned about the necessity for firewalls to protect from
> hackers, so I guess someone knows how to reach my computer - it must be
> possible! So, if anyone has any thoughts on this issue, please cc: your
> post to mlevin77@comcast.net. Thank you!!
>
> Mike
>
> --
>
> Mike Levin
> mlevin77@comcast.net
>

Michael Levin <mlevin77@comcast.net> wrote in message news:<BBE40897.B8D%mlevin77@comcast.net>...
> I have a Mac with OS X on a cablemodem (connected through a wifi network and
> a Linksys router). Comcast hands out a dynamic IP address. What I want is to
> be able to get my files when I'm on the road (by running an FTP or other
> file sharing server on my computer). The thing is, in order to get to my
> machine, I need to know the IP address when I'm away, but it changes all the
> time because of the dynamic addressing. Is there anything I'm missing? Is it
> possible to find my computer from the internet, given that it's behind a
> cablemodem? I did have one idea: I could write some code to run in
> background and have the computer dump its IP address to a file on a known
> FTP site every few hours. That way, all I'd have to do from the remote
> location is go to the FTP site, open the data file, read the current IP
> address, and use that to find my machine. Would that work? Is there any
> software which does this already (before I reinvent the wheel)? The other
> thing which is confusing me is: my computer is behind a Linksys wireless
> router, which gets its IP address from the cablemodem, but then hands out a
> "fake" (LAN) address to my machine. So, how do I actually get an address
> which can be used from the outside world to reach my machine? I am
> constantly being warned about the necessity for firewalls to protect from
> hackers, so I guess someone knows how to reach my computer - it must be
> possible! So, if anyone has any thoughts on this issue, please cc: your
> post to mlevin77@comcast.net. Thank you!!
>
> Mike

I think you want to look into this:

http://www.technopagan.org/dynamic/

They do this for you so you will have a fixed name attached to your
changing IP address. Also check your ISP might block certain outgoing
ports (for example Verizon home DSL blocks port 80 out going so you
cannot have a webserver on a standard address.)

--jim

Michael Levin wrote:

> The thing is, in order to get to my
> machine, I need to know the IP address when I'm away, but it changes all
> the time because of the dynamic addressing. Is there anything I'm missing?

There's a few that come to mind. With a Linux firewall, you could configure
it to e-mail you, whenever the IP changes. You could get one of those
firewall/router boxes that supports notifiying a DNS server of address
changes. The easiest however, may be using your host name, if it doesn't
change with your IP. In my case, I'm on dhcp, so my address may (rarely)
change, but the host name is derived from my MAC address, and never
changes. So as long as I know the assigned name, I can reach my home
network.

--

Fundamentalism is fundamentally wrong.

To reply to this message, replace everything to the left of "@" with
james.knott.

In article <BBE40897.B8D%mlevin77@comcast.net>,
Michael Levin <mlevin77@comcast.net> wrote:

> The thing is, in order to get to my machine, I need to know the IP
> address when I'm away, but it changes all the time because of the
> dynamic addressing. Is there anything I'm missing?

You might visit <http://www.dyndns.org/services/dyndns/>. I believe
this is still a free service, although I'm sure they will accept a
donation ;-)

--
Tom Stiller

PGP fingerprint = 5108 DDB2 9761 EDE5 E7E3
7BDA 71ED 6496 99C0 C7CF

vze35xda@verizon.net (Jim Schimpf) wrote in message news:<5d6ed6b4.0311212105.65668652@posting.google. com>...
> Michael Levin <mlevin77@comcast.net> wrote in message news:<BBE40897.B8D%mlevin77@comcast.net>...
> > I have a Mac with OS X on a cablemodem (connected through a wifi network and
> > a Linksys router). Comcast hands out a dynamic IP address. What I want is to
> > be able to get my files when I'm on the road (by running an FTP or other
> > file sharing server on my computer). The thing is, in order to get to my
> > machine, I need to know the IP address when I'm away, but it changes all the
> > time because of the dynamic addressing. Is there anything I'm missing? Is it
> > possible to find my computer from the internet, given that it's behind a
> > cablemodem? I did have one idea: I could write some code to run in
> > background and have the computer dump its IP address to a file on a known
> > FTP site every few hours. That way, all I'd have to do from the remote
> > location is go to the FTP site, open the data file, read the current IP
> > address, and use that to find my machine. Would that work? Is there any
> > software which does this already (before I reinvent the wheel)? The other
> > thing which is confusing me is: my computer is behind a Linksys wireless
> > router, which gets its IP address from the cablemodem, but then hands out a
> > "fake" (LAN) address to my machine. So, how do I actually get an address
> > which can be used from the outside world to reach my machine? I am
> > constantly being warned about the necessity for firewalls to protect from
> > hackers, so I guess someone knows how to reach my computer - it must be
> > possible! So, if anyone has any thoughts on this issue, please cc: your
> > post to mlevin77@comcast.net. Thank you!!
> >
> > Mike
>
> I think you want to look into this:
>
> http://www.technopagan.org/dynamic/
>
> They do this for you so you will have a fixed name attached to your
> changing IP address. Also check your ISP might block certain outgoing
> ports (for example Verizon home DSL blocks port 80 out going so you
> cannot have a webserver on a standard address.)
>
> --jim

Mike:

I would use a dynamic IP service like those found at www.dyndns.org.
Go to dynamic DNS and setup an account (free). Then you have to
download a small client as the one you are suggesting writing. I use
DirectUpdate and it works great. The computer has to be on all the
time, and this application will run constantly, it will poll for the
latest IP then update the dynamic service. You can then go to the
dynamic URL you made at DYNDNS and presto it works. Now for services,
Jim is correct, the ISP will block 80 for sure, so you will have to
make a new port for FTP server or whatever server you want. Then go to
you linksys router andmap the port to the new IP address (the fake
one, probably a 192.168.x.x). Try to hardcode this IP on the FTP
server, so it does not pull a dynamic one from the pool (DHCP).

Should work fine.
Rahul

On 21 Nov 2003 21:05:40 -0800, vze35xda@verizon.net (Jim Schimpf)
wrote:

> I think you want to look into this:
>
>http://www.technopagan.org/dynamic/
>
>They do this for you so you will have a fixed name attached to your
>changing IP address. Also check your ISP might block certain outgoing
>ports (for example Verizon home DSL blocks port 80 out going so you
>cannot have a webserver on a standard address.)

I think you mean they block incoming port 80. If they blocked outgoing
port 80, you'd have a tough time web surfing.

--
Bill