Parsing nmap output

Question

A project to familiarize myself that I'm working on is to parse through an nmap result.

(I know of the -oG option, but I'm working with grep, awk, for, and while loops here).

Below is what I'm trying to parse through:

Starting Nmap 7.60 ( https://nmap.org ) at 2017-12-05 11:26 EST
Nmap scan report for house.router.nick (192.168.1.1)


Host is up (0.00059s latency).
Not shown: 995 closed ports
PORT     STATE SERVICE
22/tcp   open  ssh
53/tcp   open  domain
427/tcp  open  svrloc
1900/tcp open  upnp

MAC Address: 50:C7:BF:A8:CF:C8 (Tp-link Technologies)


Nmap scan report for 192.168.1.2


Host is up (0.00034s latency).
Not shown: 996 closed ports
PORT      STATE SERVICE
22/tcp    open  ssh
80/tcp    open  http
139/tcp   open  netbios-ssn
445/tcp   open  microsoft-ds

MAC Address: 48:F8:B3:C9:AE:BB (Cisco-Linksys)

What I want to get is this:

22/ssh
====
192.168.1.1
192.168.1.2

http
===
192.168.1.2

So far, I have this:

grep -E "tcp.*open" nmap.txt | awk '{ print $3 }' | sort | uniq

For the life of me, I can't figure out how to get this into a loop of sorts and get the desired output from above.

Can you please help me learn and explain why you came to the solution you did? No point in getting a potential solution if I can't understand the logic behind it.

Answer 1

You'd be better served using a general purpose programming language (python, perl, awk) where you can capture the IP address when you see the "scan report for" keywords, and then maintain a data structure mapping the service names to the list of IP addresses running those services.

For example, given that output, this perl one-liner (offered without explanation)

perl -ne '
    if (/Nmap scan report for .*?(\d+\.\d+\.\d+\.\d+)/) {
        $ip = $1
    }
    elsif (/^(\d+)\/tcp\s+open\s+(.*)/) {
        push @{$services{"$1/$2"}}, $ip
    }
    END {
        for $svc (sort {$a <=> $b} keys %services) {
            printf "%s\n%s\n\n", $svc, join("\n", @{$services{$svc}})
        }
    }
'

produces

22/ssh
192.168.1.1
192.168.1.2

53/domain
192.168.1.1

80/http
192.168.1.2

139/netbios-ssn
192.168.1.2

427/svrloc
192.168.1.1

445/microsoft-ds
192.168.1.2

1900/upnp
192.168.1.1

Answer 2

$ cat tst.awk
BEGIN { FS="[[:space:]/]+" }

/Nmap scan report/ {
    ip = $NF
    gsub(/[()]/,"",ip)
}

/tcp.*open/ {
    key = $1 "/" $4
    ips[key] = (key in ips ? ips[key] ORS : "") ip
}

END {
    for (key in ips) {
        print key
        print "===="
        print ips[key]
        print ""
    }
}

.

$ awk -f tst.awk file
80/http
====
192.168.1.2

1900/upnp
====
192.168.1.1

427/svrloc
====
192.168.1.1

445/microsoft-ds
====
192.168.1.2

53/domain
====
192.168.1.1

22/ssh
====
192.168.1.1
192.168.1.2

139/netbios-ssn
====
192.168.1.2

I think it's extremely obvious what it's doing but if you have any questions after maybe a few glances at the awk man page then feel free to ask.

The above will work using any awk in any shell on every UNIX system.