I have a list of ip addresses in cidr formart in a text file,one cidr per line and I would like to calculate the broadcast ip address of the cidr. I understand that I can do that using ipcalc with the -b option but ipcalc doesn't take a text file full of cidr. So, how to write a bash script to wrap around the ipcal command.
Here's a quick script that should do the trick:
Example file ips.txt
$ cat ips.txt
192.168.0.1/24
192.167.0.1/24
Example output for the ips in this file:
$ for i in $(cat ips.txt);do echo $i; ipcalc -b $i;done
192.168.0.1/24
BROADCAST=192.168.0.255
192.167.0.1/24
BROADCAST=192.167.0.255
If you don't need to output the ip address itself, just remove the echo.
Edit
Here's a version that prints only the broadcast address, as requested:
$ for i in $(cat ips.txt);do bcaddr=$(ipcalc -b $i);echo ${bcaddr#BROADCAST=};done
192.168.0.255
192.167.0.255
Related
I have a list (text file) with the following data:
app1 example1.google.com
app2 example2.google.com
dev1 device1.google.com
cell1 iphone1.google.com
I want to check the ip address of the URLs/hostnames and update the text file with the gathered ip. Example:
app1 example1.google.com 192.168.1.10
app2 example2.google.com 192.168.1.55
dev1 device1.google.com 192.168.1.53
cell1 iphone1.google.com 192.168.1.199
You can use dig to get the IP (but the domains must exist). Not tested for IPv6.
#! /bin/bash
while read name url ; do
ip=$(dig -4 $url | grep '^[^;]' | grep -o '\([0-9]*[.:]\)\+[0-9.:]*$')
printf '%s %s %s\n' "$name" "$url" "$ip"
done < data.txt
If there are only two columns in the file, this might help:
awk '{"dig +short " $2 | getline ip ; print $1, $2, ip}' file
First we run a subshell (not really a good idea to run this for zillions of records) and in it a "dig +short" (the shortest possibility which came to my mind to get IP address only) with the FQDN of a machine (found in the second column). Then we print all the original columns and the new one too (with the IP address). Output can be redirected to a new file with a single >. I wouldn't consider "safe" to edit original files.
nslookup google.com
Server: xx.xx.xx.xx
Address: xx.xx.xxx.xx#53
Non-authoritative answer:
Name: google.com
Address: 172.217.164.110
I just need the last IP Address with grep/awk like below, please help.
172.217.164.110
Can be enhanced, but it'll do what you want:
nslookup google.com | sed -n '/Name:/{x;n;p;d;}; x' | awk '{print $2}'
Output (when only one Name+Address block is returned by nslookup):
172.217.164.110
I used sed's pattern space advanced options, printing the line following the "Name: google.com" line (x;n;p; sequence after "Name:" pattern match). I am not a sed guru, I used this Unix Stack Exchange answer, then awk to get only the IP following a whitespace.
In a IPv6 setting, you can get both the IPv4 and the IPv6 addresses, in two lines, so if this is not what you want, you will have to filter out the IPv6, using a pattern that only matches the format of an IPv4.
I need to resolve a host name to an IP address in a shell script. The code must work at least in Cygwin, Ubuntu and OpenWrt(busybox).
It can be assumed that each host will have only one IP address.
Example:
input
google.com
output
216.58.209.46
EDIT:
nslookup may seem like a good solution, but its output is quite unpredictable and difficult to filter. Here is the result command on my computer (Cygwin):
>nslookup google.com
Unauthorized answer:
Serwer: UnKnown
Address: fdc9:d7b9:6c62::1
Name: google.com
Addresses: 2a00:1450:401b:800::200e
216.58.209.78
I've no experience with OpenWRT or Busybox but the following one-liner will should work with a base installation of Cygwin or Ubuntu:
ipaddress=$(LC_ALL=C nslookup $host 2>/dev/null | sed -nr '/Name/,+1s|Address(es)?: *||p')
The above works with both the Ubuntu and Windows version of nslookup. However, it only works when the DNS server replies with one IP (v4 or v6) address; if more than one address is returned the first one will be used.
Explanation
LC_ALL=C nslookup sets the LC_ALL environment variable when running the nslookup command so that the command ignores the current system locale and print its output in the command’s default language (English).
The 2>/dev/null avoids having warnings from the Windows version of nslookup about non-authoritative servers being printed.
The sed command looks for the line containing Name and then prints the following line after stripping the phrase Addresses: when there's more than one IP (v4 or 6) address -- or Address: when only one address is returned by the name server.
The -n option means lines aren't printed unless there's a p commandwhile the-r` option means extended regular expressions are used (GNU sed is the default for Cygwin and Ubuntu).
If you want something available out-of-the-box on almost any modern UNIX, use Python:
pylookup() {
python -c 'import socket, sys; print socket.gethostbyname(sys.argv[1])' "$#" 2>/dev/null
}
address=$(pylookup google.com)
With respect to special-purpose tools, dig is far easier to work with than nslookup, and its short mode emits only literal answers -- in this case, IP addresses. To take only the first address, if more than one is found:
# this is a bash-specific idiom
read -r address < <(dig +short google.com | grep -E '^[0-9.]+$')
If you need to work with POSIX sh, or broken versions of bash (such as Git Bash, built with mingw, where process substitution doesn't work), then you might instead use:
address=$(dig +short google.com | grep -E '^[0-9.]+$' | head -n 1)
dig is available for cygwin in the bind-utils package; as bind is most widely used DNS server on UNIX, bind-utils (built from the same codebase) is available for almost all Unix-family operating systems as well.
Here's my variation that steals from earlier answers:
nslookup blueboard 2> /dev/null | awk '/Address/{a=$3}END{print a}'
This depends on nslookup returning matching lines that look like:
Address 1: 192.168.1.100 blueboard
...and only returns the last address.
Caveats: this doesn't handle non-matching hostnames at all.
TL;DR; Option 2 is my preferred choice for IPv4 address. Adjust the regex to get IPv6 and/or awk to get both. There is a slight edit to option 2 suggested use given in EDIT
Well a terribly late answer here, but I think I'll share my solution here, esp. because the accepted answer didn't work for me on openWRT(no python with minimal setup) and the other answer errors out "no address found after comma".
Option 1 (gives the last address from last entry sent by nameserver):
nslookup example.com 2>/dev/null | tail -2 | tail -1 | awk '{print $3}'
Pretty simple and straight forward and doesn't really need an explanation of piped commands.
Although, in my tests this always gave IPv4 address (because IPv4 was always last line, at least in my tests.) However, I read about the unexpected behavior of nslookup. So, I had to find a way to make sure I get IPv4 even if the order was reversed - thanks regex
Option 2 (makes sure you get IPv4):
nslookup example.com 2>/dev/null | sed 's/[^0-9. ]//g' | tail -n 1 | awk -F " " '{print $2}'
Explanation:
nslookup example.com 2>/dev/null - look up given host and ignore STDERR (2>/dev/null)
sed 's/[^0-9. ]//g' - regex to get IPv4 (numbers and dots, read about 's' command here)
tail -n 1 - get last 1 line (alt, tail -1)
awk -F " " '{print $2} - Captures and prints the second part of line using " " as a field separator
EDIT: A slight modification based on a comment to make it actually more generalized:
nslookup example.com 2>/dev/null | printf "%s" "$(sed 's/[^0-9. ]//g')" | tail -n 1 | printf "%s" "$(awk -F " " '{print $1}')"
In the above edit, I'm using printf command substitution to take care of any unwanted trailing newlines.
I'm learning about sed but it is very difficult to me understand it.
I have adsl with dynamic ip so and i want to put current ip on hosts file.
This following script just tells me the current wan ip address and no more:
IP=$(dig +short myip.opendns.com #resolver1.opendns.com)
echo $IP
The result:
192.42.7.73
So, i have a line on hosts file with the old ip address:
190.42.44.22 peep.strudel.com
and i want to update host file like this:
192.42.7.73 peep.strudel.com
How can i do it? I think i can use the hostname as pattern...
The reason of doing this is because my server is a client of my router, so it access the internet thru its gateway and not directly. And postfix always is logging me that "connect from unknown [x.x.x.x]" (where x.x.x.x is my wan ip!) and it can't resolve that ip. I think that maybe if i specify this relating with my fqdn host/domain, on hosts file it will works better.
Thanks
Sergio.
You can use a simple shell script:
#! /bin/bash
IP=$(dig +short myip.opendns.com #resolver1.opendns.com)
HOST="peep.strudel.com"
sed -i "/$HOST/ s/.*/$IP\t$HOST/g" /etc/hosts
Explanation:
sed -i "/$HOST/ s/.*/$IP\t$HOST/g" /etc/hosts means in the line which contains $HOST replace everything .* by $IP tab $HOST.
using sed
sed -r "s/^ *[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+( +peep.strudel.com)/$IP\1/"
.
[0-9]+\. find all lines that matches 1 or more digits with this pattern 4 consecutive times then pattern peep.strudel.com .The parenthesis around the pattern peep.strudel.com save it as \1 then replace the whole patten with your variable and your new ip.
another approach:instead of saving pattern to a variable named IP, you can execute your command line inside sed command line to get the new IP .
sed -r "s/^ *[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+( +peep.strudel.com)/$(dig +short myip.opendns.com #resolver1.opendns.com)\1/"
using gawk
gawk -v IP=$IP '/ *[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+( +peep.strudel.com).*/{print gensub(/ *[0-9]+\.[0-9]+\.[0-9]+\.[0-9]+( +peep.strudel.com)/,IP"\\1","g")}'
You need to include the sed code inside double quotes so that the used variable got expanded.
sed "s/\b\([0-9]\{1,3\}\.\)\{1,3\}[0-9]\{1,3\}\b/$IP/g" file
Add -i parameter to save the changes made. In basic sed \(..\) called capturing group. \{min,max\} called range quantifier.
Example:
$ IP='192.42.7.73'
$ echo '190.42.44.22 peep.strudel.com' | sed "s/\b\([0-9]\{1,3\}\.\)\{1,3\}[0-9]\{1,3\}\b/$IP/g"
192.42.7.73 peep.strudel.com
I've got a tcpdump command running from a bash script. looks something like this.
tcpdump -nttttAr /path/to/file -F /my/filter/file
The filter file has a combination of ip addresses and host names. i.e.
host 111.111.111.111 or host 112.112.112.112 and not (host abc.com or host def.com or host zyx.com).
And it works great - as long as the host names are all valid. My problem is sometimes these hostnames will not be valid and upon encountering one - tcpdump spits out
tcpdump: Unknown Host
I thought with the -n option it would skip dns lookup - but in anycase I need it to ignore the unknown host and continue along the filter file.
Any ideas?
Thank you in advance.
The -n option prevents conversion of IP addresses into names, but not the other way around. If you supply a hostname as an argument, it has to be looked up to get the IP address since packets only contain the numeric address and not the hostname. However, there ought to be a way to ignore invalid hostnames, but I can't find one. Perhaps you could pre-process your filter file using dig.
dig +short non-existent-domain.com # returns null
dig +short google.com # returns multiple IP addresses
This could probably be better, but it should show you hostnames in your filter file that aren't valid:
grep -Po '(?<=host )[^ )]*' filterfile | grep -v '[0-9]$' | xargs -I % sh -c 'echo -n "% "; echo $(dig +short %)' | grep -v ' [0-9]'
Any hostnames it prints didn't have IP addresses returned by dig.