how to write an undetectable port scanner of my own..

[ramforu]

hi geeks,

hello frens.....i want to know tips and directions towards developing a port scanner of my own....
i want to know this as purely for an edu purpose..plz help me

thanx
ram

[SonofGalen]

I'd say the first thing you need to do is study up on the basics of TCP/IP. Learn about the different kinds of packets, the different protocols. I'd also study up some on how the ping and nmap command works.

[HDD]

An extremely good book to read is "A Complete H@Cker's Handbook: Everything You Need to Know About Hacking in the Age of the Web" writen by Dr. K (ISBN: 1858684064). It doesn't directly teach you how to hack but the theory of it (in terms of protocols and packets). The port scanning section was very good, it doesn't tell you how to make your own port scanner directly but is a good guide.

[tyfon]

1)no geeks here
2)do you know any programming,networking? I mean making a scanner is not such an easy task...
3)read a lot
4)google
5)read a lot again
6)nmap is always there and it is pretty good
anyway good luck

[R[A]100]

You can find all the info to make a port scanner at the msdn [microsoft devolpers network] they have a lot of scripts on the subject in vb.

[nihil]

how to write an undetectable port scanner of my own

Totally impossible..............if you scan a port you attempt to make contact....if you attempt contact, you can be detected?

Sure you can write a port scanner..follow the sound advice already given.......but the only "undetectable" port scanner that I know of is one that doesn't work

Cheers

[Shrekkie]

Why writing a new one, while you can have good coverage from and with nmap...

[Modderfokker]

An extremely good book to read is "A Complete H@Cker's Handbook: Everything You Need to Know About Hacking in the Age of the Web" writen by Dr. K (ISBN: 1858684064). It doesn't directly teach you how to hack but the theory of it (in terms of protocols and packets). The port scanning section was very good, it doesn't tell you how to make your own port scanner directly but is a good guide.

Got the book in my hand right now, it doesnt have a section on port scanning. But throughout the book it shows you how to manually portscan using telnet. (lol guess and test). But i would recomend it to people with little experience to want a grip on this stuff (whether white or black hat). but medium to experienced users forget it.

[slarty]

There are several method to make a TCP port scan less detectable:

1. Use half-open connections or other badly sequenced packets
2. Use some kind of "bounce" attack

In the latter case, you protect your IP because the victim (?) does not see your real IP.

However, 1. is much better for general usage, example scanning internal networks or pen testing. Half-open (SYN) scanning is ideal, because it only finds truly open ports (no false negatives), and causes minimum disruption - in most OSs the application does not even "see" the connections.

Of course IDS can detect just about any type of scan, but the "stealth" scans only defend against application-level logging.

Note that all the above pertains to TCP port scanning only, UDP scanning (or other protocols) do not have "syn" flags, hence cannot be masked from the application in this way.

In order to even *think* about coding this, you will need to be competent in TCP and IP. You will need to know the structure of a TCP packet and have a routine to calculate TCP checksums (I think).

If you are thinking you can write this in 20 lines of VB, you are totally mistaken.

Slarty

[qod]

Originally posted here by nihil
Totally impossible..............if you scan a port you attempt to make contact....if you attempt contact, you can be detected?

Sure you can write a port scanner..follow the sound advice already given.......but the only "undetectable" port scanner that I know of is one that doesn't work

Cheers

using a passive scanning you are able to be invisable, look at tools such as p0f and as said, READ ALOT.