multiline search in grep - bash

Question

I have made a text file of nmap's output and i was trying to find only those ip whose port are open
and when i am using grep i am not getting the desired output only one of the item is i am able to get either ip or the text open
data:
Nmap scan report for xxx.xxx.xxx.83
Host is up (0.050s latency).
PORT STATE SERVICE
80/tcp closed http
Nmap scan report for xxx.xxx.xxx.87
Host is up (0.049s latency).
PORT STATE SERVICE
80/tcp filtered http
Nmap scan report for xxx.xxx.xxx.89
Host is up (0.051s latency).
PORT STATE SERVICE
80/tcp filtered http
Nmap scan report for xxx.xxx.xxx.90
Host is up (0.050s latency).
PORT STATE SERVICE
80/tcp closed http
Nmap scan report for xxx.xxx.xxx.93
Host is up (0.051s latency).
PORT STATE SERVICE
80/tcp open http
Nmap scan report for xxx.xxx.xxx.96
Host is up (0.051s latency).
PORT STATE SERVICE
80/tcp filtered http
Nmap scan report for xxx.xxx.xxx.100
Host is up (0.054s latency).
PORT STATE SERVICE
80/tcp filtered http

Answer 1

You could try the below awk command,
$ awk -v RS="" '/ open /{print $5}' file
xxx.xxx.xxx.93
It prints the ip (column no 5) only if the certain block contains the text open

Answer 2

After awk and grep perl too:
perl -00 -lanE 'say $_ if m/open/' < file
prints:
Nmap scan report for xxx.xxx.xxx.93
Host is up (0.051s latency).
PORT STATE SERVICE
80/tcp open http
or
perl -00 -lanE 'say $F[4] if m/open/' < file
prints
xxx.xxx.xxx.93

Answer 3

If there are always 4 lines per block and the word open is in the last line, you can do:
grep -B4 open file
and it will show the 4 lines before the word open.

Answer 4

What about using awk? This will report the IP address the first time an open port is encountered in the nmap output:
sh$ awk '$3=="report"{ IP = $5 } $2=="open"&&IP { print IP; IP="" }' nmap.out
xxx.xxx.xxx.93