How to interpret TCP/ip fingerprint when scanning for OS?

Solution 1:

The fingerprinting does a several measurements which are then compared to a database of previously known Operating System fingerprints to find a match.

It isn't really meant to be read so much as submitted along with the know OS to expand the fingerprint database. Inside of OS: each probe is listed as PROBNAME(DATA)

SCAN(V=5.05BETA1%D=8/23%OT=22%CT=1%CU=42341%PV=N%DS=0%DC=L%G=Y%TM=4A91CB90%P=i686-pc-linux-gnu)
SEQ(SP=C9%GCD=1%ISR=CF%TI=Z%CI=Z%II=I%TS=A)
OPS(O1=M400CST11NW5%O2=M400CST11NW5%O3=M400CNNT11NW5%O4=M400CST11NW5%O5=M400CST11NW5%O6=M400CST11)
WIN(W1=8000%W2=8000%W3=8000%W4=8000%W5=8000%W6=8000)
ECN(R=Y%DF=Y%T=40%W=8018%O=M400CNNSNW5%CC=N%Q=)
T1(R=Y%DF=Y%T=40%S=O%A=S+%F=AS%RD=0%Q=)
T2(R=N)
T3(R=Y%DF=Y%T=40%W=8000%S=O%A=S+%F=AS%O=M400CST11NW5%RD=0%Q=)
T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)
T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)
T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)
T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)
U1(R=Y%DF=N%T=40%IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)
IE(R=Y%DFI=N%T=40%CD=S)

One common way that is listed to the examples in the nmap documentation is to also scan for versions with:

nmap -sV -O -v hostname

The services and versions reported will usually let you tell what device or type of device it is even if the OS detection itself gives you little. For example if the web server gets a version line like:

80/tcp   open  http       Apache httpd 2.2.15 ((CentOS))

Solution 2:

I looked up that OS:SCAN V=5.05 and I found this

http://nmap.org/book/osdetect-unidentified.html
The following below, is straight from that nmap link above.
Notice it also has the string V=5.05BETA1 So, output very similar to yours

When Nmap Fails to Find a Match and Prints a Fingerprint

When Nmap detects that OS detection conditions seem ideal and yet it finds no exact matches, it will print out a message like this:

No OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ).

> TCP/IP fingerprint:
> OS:SCAN(V=5.05BETA1%D=8/23%OT=22%CT=1%CU=42341%PV=N%DS=0%DC=L%G=Y%TM=4A91CB
> OS:90%P=i686-pc-linux-gnu)SEQ(SP=C9%GCD=1%ISR=CF%TI=Z%CI=Z%II=I%TS=A)OPS(O1
> OS:=M400CST11NW5%O2=M400CST11NW5%O3=M400CNNT11NW5%O4=M400CST11NW5%O5=M400CS
> OS:T11NW5%O6=M400CST11)WIN(W1=8000%W2=8000%W3=8000%W4=8000%W5=8000%W6=8000)
> OS:ECN(R=Y%DF=Y%T=40%W=8018%O=M400CNNSNW5%CC=N%Q=)T1(R=Y%DF=Y%T=40%S=O%A=S+
> OS:%F=AS%RD=0%Q=)T2(R=N)T3(R=Y%DF=Y%T=40%W=8000%S=O%A=S+%F=AS%O=M400CST11NW       
> OS:5%RD=0%Q=)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)T5(R=Y%DF=Y%T=40%W
> OS:=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD=0%Q=)
> OS:T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1(R=Y%DF=N%T=40%IPL=164%U
> OS:N=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI=N%T=40%CD=S)

Please consider submitting the fingerprint so that all Nmap users can benefit. It only takes a minute or two and it may mean you don't need to see that ugly message again when you scan the host with the next Nmap version! Simply visit the URL Nmap provides for instructions.

If Nmap finds no matches and yet prints no fingerprint, conditions were not ideal. Even if you obtain the fingerprint through debug mode or XML output, please don't submit it unless Nmap asks you to (as in the previous example).