Modem is connected, what's the IP address

[Waidesworld]

I have a remote computer which is currently dialled up to the net on a local ISP phone number. I want to find the IP address so I can access it using my remote program, however using IP scanner may take forever. Is there any way I can find out what the IP bank for the ISP in that area is then I could do a port scan for my system.

 

[John Lewis]

You could probably do so by finding the IP one time doing a 'ipconfig /all' in a command window, then guess as to the range in use.

That would not be very nice, however. Portscanning is not considered polite behavior, regardless of your intentions.

If there is someone at the computer on the other end, why not have them do the ipconfig and relay the information to you each time?

If there isn't someone there, why not use dynamic dns (see

http://www.dyndns.org

or search the web for 'dynamic dns service')?

Either way, be kind to your web neighbors. Don't port scan. It uses precious bandwidth for dialup users. Can also cause firewall log entries on other computers causing many useless posts in security newsgroups. We don't need that.

 

[Waidesworld]

When I port scan I check a specific port, so I am not affecting too many if any at all. My typical results on a port scan were about 10-12 open ports from a scan of 255 x 3 IP addresses. However for some reason the IP settings for the remote seem to have changed as they have donme monthly over the last year or so. It is a remote machine so noone is available and it is over 100 miles away.

We looked at dynamic dns before and I think this time we need to bring it a step further.

Thanks

 

[Waidesworld]

dydns is fine but it still requires an IP address to start and I don't have that.

 

[John Lewis]

If you have an address to start with, you could go to

http://www.arin.net

(assuming North America) and do a whois search. The results would at least tell you what size block was allocated, although the ISP may have a large subnet allocated then divided internally to service different areas.

On the dyndns, that would also require some configuration on the remote computer, but I still think it would serve you better in the long run.

On the issue of port scans . . . it doesn't matter how many open ports you find, many firewalls will reject a packet then log it. Still can raise alarms sometimes. If you really stick to addresses that are strictly assigned to dialup, probably not an issue from that standpoint due to the lack of firewalls on most dialup machines. Many (myself included) still would not consider it to be 'polite' behaviour.

 

[manarth]

What o/s is the remote server running?

dydns is fine but it still requires an IP address to start and I don't have that.

Dyn-dns (

http://www.dyn-dns.org

/

http://www.no-ip.com)

allows you to choose a domain name. You can then run a small application on the server (versions available for linux, windows and solaris) which updates dyn-dns's DNS server whenever your IP changes. No human intervention required!

Port scans on public IPs are generally considered bad - and may be against your ISP's ToS, or even illegal in some countries. The onus may be on you to prove that it wasn't for malicious activity.

<marc> i wonder what will happen if i press this...[ul][li]please give feedback on what works / what doesn't[/li][li]need some help? how to get a better answer: faq581-3339[/li][/ul]