I am running multiple docker containers with docker-compose and all of them are in the same network.
Once the containers are up and running I would like to access from one of them to all the others through a shell script, where that script retrieves all IP addresses of the other containers from the docker network (first Ethernet interface eth0 inside the container).
I know there's a way to get IP addresses using container name, but I am running docker-compose with --scale flag so the script doesn't know how many containers are in that network, I am confused and don't know how to do that.
The base image of all containers is ubuntu:20.04
Since I couldn't find a simple way for now I created a script using nmap and ifconfig, it consists on getting the IP address of inet (Ethernet interface) from one of the docker machines then lookup on that network using nmap:
#!/bin/bash
EI=$(/sbin/ifconfig eth0 | grep inet | awk '{ print $2}') # Get inet IP of eth0
IPS=($(nmap $EI/24 | grep dindood | awk '{ print $6}' | sed 's/.$//; s/^.//')) # Look for the nodes Ip addresses
NAMES=($(nmap $EI/24 | grep dindood | awk '{ print $5}' | cut -f1 -d".")) # Look for the nodes Containers names
echo "host ip=$EI"
for i in "${!IPS[#]}"; do #loop through IP addresses found
echo "hostname= ${NAMES[$i]} | IP= ${IPS[$i]}"
done
the output looked like this for me:
host ip=192.168.160.3
hostname= my_project_container_2 | IP= 192.168.160.2
hostname= my_project_container_1 | IP= 192.168.160.4
I am trying to grep the third octet in IP address to an tap device on remote machine.
ssh -t user#host "/sbin/ifconfig tap0 | grep "inet" | /usr/bin/awk -F'[: ]+' '{ print $4 }' | awk -F'[.]' '{print $3}'"
I am resulting this:
inet addr:10.22.66.77 Bcast:10.22.66.255 Mask:255.255.255.0
When i run the command on the remote machine it shows 66
How to make it working with ssh -t?
Sometimes using perl is simpler:
ssh -t user#host "/sbin/ifconfig tap0" | perl -n -e 'if (/inet\saddr:\d+\.\d+\.(\d+)/) { print "$1\n"}'
it runs regular expression pattern on the local machine match on the third octet following addr: and this is then printed via $1
The pattern match is run on the local machine to avoid problems with escaping " (In your example code the " in the grep inet seems to terminate the ssh...)
currently I am working on a school assignment on Linux using Vim where I have to write a script that displays the user that is currently logged in, the time and date, and list only the IP address of the Nic card. I have everything working except for the IP address part. If anyone could help I would appreciate it greatly.
Edit to include the code I have at the moment.
#!/bin/bash
Time=$(date)
IP=$(ifconfig ens33)
echo "The following user is currently logged in $USER"
echo ""
echo "The current time is $Time"
echo ""
echo "The IP information is $IP"
You can filter the result of ifconfig using awk like this (IPv4):
$ ifconfig ens33 | awk '/inet addr/{print substr($2, 6)}'
Result:
10.10.xx.xx
inet addr: represents IPv4 address.
inet6 addr: represents IPv6 address.
this line
IP=$(ifconfig ens33| grep inet | sed 's/ */ /' | cut -d" " -f3)
I have a code which detects if OpenVPN connection is up or down:
if echo 'ifconfig tun0' | grep -q "00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00"
then
echo "VPN up"
else
echo "VPN down"
fi
exit 0
now I'm trying to re-write the code to work with PPTP or IPSEC connection. I've tried to do:
if echo 'ifconfig ppp0' | grep -q "00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00"
or the same with ipsec but does not work. Is there any other way to detect PPTP or IPSEC connection?
That echo statement is erroneous. As #unwind says, the single quotes (') should be backtics (`). Your current code is sending the literal value ifconfig ppp0 to grep, which doesn't do anything useful.
But you don't actually need the backtics, either. You can just send the output of ifconfig to grep directory; using echo doesn't get you anything:
if ifconfig ppp0 | grep -q "00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00"; then
echo ppp connection is up
fi
The following script will:
Run the ISPConnectivity.sh script every 5 minutes. This will mean that the VPN tunnel will not be down for more than 5 minutes.
Check if the tun interface is down, and start the vpn script if it is.
Check connectivity if the tun0 interface is up. It does ping tests on 2 Public IPs (if I get even a single response from 1 of the IPs tested, I consider this a success ), and all have to fail to run the vpn script. I ran ping tests on multiple hosts to prevent the vpn script from starting in case the ping test failed on 1 IP.
Send all failure output to a file in my home directory. I do not need to see if any test succeeded.
Contents of sudo crontab:
*/5 * * * * /home/userXXX/ISPConnectivity.sh >> /home/userXXX/ISPConnectivity.log 2>&1
Contents of ISPConnectivity.sh script:
#!/bin/bash
# add ip / hostname separated by white space
#HOSTS="1.2.3.4"
HOSTS="8.8.8.8 4.2.2.4"
# no ping request
totalcount=0
COUNT=4
DATE=`date +%Y-%m-%d:%H:%M:%S`
if ! /sbin/ifconfig tun0 | grep -q "00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00"
then
echo $DATE tun0 down
sudo /home/userXXX/startVPN.sh start
else
for myHost in $HOSTS;
do
count=`ping -c $COUNT $myHost | grep 'received' | awk -F',' '{ print $2 }' | awk '{ print $1 }'`
totalcount=$(($totalcount + $count))
done
if [ $totalcount -eq 0 ]
then
echo $DATE $totalcount "fail"
sudo /home/userXXX/startVPN.sh start
#else
# echo $DATE $totalcount "pass"
fi
fi
You can also check with the nmcli command, to check if VPN is running or not.
nmcli c show --active | grep vpn
I'm actually looking into more flexible solution eg:
MyIP=$(curl http://api.ipify.org/?format=text)
if [ "$MyIP" != "MYORYGINALIP" ]
then
echo "IPSEC VPN is Running - " $MyIP
else
echo "IPSEC VPN is Not Running - " $MyIP
fi
exit 0
what about that? can I improve it any way?
ip route list table 220 if Ip address shown -> VPN connection established, none -> no VPN
or
if [ "0" == ifconfig | grep wlan0 | wc -l ]; then echo "NO wlan0 has no VPN"; else echo "YES wlan0 has VPN"; fi
How can I write a Linux Bash script that tells me which computers are ON in my LAN?
It would help if I could give it a range of IP addresses as input.
I would suggest using nmap's ping-scan flag,
$ nmap -sn 192.168.1.60-70
Starting Nmap 4.11 ( http://www.insecure.org/nmap/ ) at 2009-04-09 20:13 BST
Host machine1.home (192.168.1.64) appears to be up.
Host machine2.home (192.168.1.65) appears to be up.
Nmap finished: 11 IP addresses (2 hosts up) scanned in 0.235 seconds
That said, if you want to write it yourself (which is fair enough), this is how I would do it:
for ip in 192.168.1.{1..10}; do ping -c 1 -t 1 $ip > /dev/null && echo "${ip} is up"; done
..and an explanation of each bit of the above command:
Generating list of IP addresses
You can use the {1..10} syntax to generate a list of numbers, for example..
$ echo {1..10}
1 2 3 4 5 6 7 8 9 10
(it's also useful for things like mkdir {dir1,dir2}/{sub1,sub2} - which makes dir1 and dir2, each containing sub1 and sub2)
So, to generate a list of IP's, we'd do something like
$ echo 192.168.1.{1..10}
192.168.1.1 192.168.1.2 [...] 192.168.1.10
Loops
To loop over something in bash, you use for:
$ for thingy in 1 2 3; do echo $thingy; done
1
2
3
Pinging
Next, to ping.. The ping command varies a bit with different operating-systems, different distributions/versions (I'm using OS X currently)
By default (again, on the OS X version of ping) it will ping until interrupted, which isn't going to work for this, so ping -c 1 will only try sending one packet, which should be enough to determine if a machine is up.
Another problem is the timeout value, which seems to be 11 seconds on this version of ping.. It's changed using the -t flag. One second should be enough to see if a machine on the local network is alive or not.
So, the ping command we'll use is..
$ ping -c 1 -t 1 192.168.1.1
PING 192.168.1.1 (192.168.1.1): 56 data bytes
--- 192.168.1.1 ping statistics ---
1 packets transmitted, 0 packets received, 100% packet loss
Checking ping result
Next, we need to know if the machine replied or not..
We can use the && operator to run a command if the first succeeds, for example:
$ echo && echo "It works"
It works
$ nonexistantcommand && echo "This should not echo"
-bash: nonexistantcommand: command not found
Good, so we can do..
ping -c 1 -t 1 192.168.1.1 && echo "192.168.1.1 is up!"
The other way would be to use the exit code from ping.. The ping command will exit with exit-code 0 (success) if it worked, and a non-zero code if it failed. In bash you get the last commands exit code with the variable $?
So, to check if the command worked, we'd do..
ping -c 1 -t 1 192.168.1.1;
if [ $? -eq 0 ]; then
echo "192.168.1.1 is up";
else
echo "ip is down";
fi
Hiding ping output
Last thing, we don't need to see the ping output, so we can redirect stdout to /dev/null with the > redirection, for example:
$ ping -c 1 -t 1 192.168.1.1 > /dev/null && echo "IP is up"
IP is up
And to redirect stderr (to discard the ping: sendto: Host is down messages), you use 2> - for example:
$ errorcausingcommand
-bash: errorcausingcommand: command not found
$ errorcausingcommand 2> /dev/null
$
The script
So, to combine all that..
for ip in 192.168.1.{1..10}; do # for loop and the {} operator
ping -c 1 -t 1 192.168.1.1 > /dev/null 2> /dev/null # ping and discard output
if [ $? -eq 0 ]; then # check the exit code
echo "${ip} is up" # display the output
# you could send this to a log file by using the >>pinglog.txt redirect
else
echo "${ip} is down"
fi
done
Or, using the && method, in a one-liner:
for ip in 192.168.1.{1..10}; do ping -c 1 -t 1 $ip > /dev/null && echo "${ip} is up"; done
Problem
It's slow.. Each ping command takes about 1 second (since we set the -t timeout flag to 1 second). It can only run one ping command at a time.. The obvious way around this is to use threads, so you can run concurrent commands, but that's beyond what you should use bash for..
"Python threads - a first example" explains how to use the Python threading module to write a multi-threaded ping'er.. Although at that point, I would once again suggest using nmap -sn..
In the real world, you could use nmap to get what you want.
nmap -sn 10.1.1.1-255
This will ping all the addresses in the range 10.1.1.1 to 10.1.1.255 and let you know which ones answer.
Of course, if you in fact want to do this as a bash exercise, you could run ping for each address and parse the output, but that's a whole other story.
Assuming my network is 10.10.0.0/24, if i run a ping on the broadcast address like
ping -b 10.10.0.255
I'll get an answer from all computers on this network that did not block their ICMP ping port.
64 bytes from 10.10.0.6: icmp_seq=1 ttl=64 time=0.000 ms
64 bytes from 10.10.0.12: icmp_seq=1 ttl=64 time=0.000 ms
64 bytes from 10.10.0.71: icmp_seq=1 ttl=255 time=0.000 ms
So you just have to extract the 4th column, with awk for example:
ping -b 10.10.0.255 | grep 'bytes from' | awk '{ print $4 }'
10.10.0.12:
10.10.0.6:
10.10.0.71:
10.10.0.95:
Well, you will get duplicate, and you may need to remove the ':'.
EDIT from comments :
the -c option limits the number of pings
since the script will end, we can also limit ourself on unique IPs
ping -c 5 -b 10.10.0.255 | grep 'bytes from' | awk '{ print $4 }' | sort | uniq
There is also fping:
fping -g 192.168.1.0/24
or:
fping -g 192.168.1.0 192.168.1.255
or show only hosts that are alive:
fping -ag 192.168.1.0/24
It pings hosts in parallel so the scan is very fast. I don't know a distribution which includes fping in its default installation but in most distributions you can get it through the package manager.
Also using the "ping the broadcast address" method pointed out by chburd, this pipe should do the trick for you:
ping -c 5 -b 10.11.255.255 | sed -n 's/.* \([0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+\).*/\1/p' | sort | uniq
Of course, you'd have to change the broadcast address to that of your network.
Just for fun, here's an alternate
#!/bin/bash
nmap -sP 192.168.1.0/24 > /dev/null 2>&1 && arp -an | grep -v incomplete | awk '{print$2}' | sed -e s,\(,, | sed -e s,\),,
If you're limiting yourself to only having the last octet changing, this script should do it. It should be fairly obvious how to extend it from one to multiple octets.
#! /bin/bash
BASE=$1
START=$2
END=$3
counter=$START
while [ $counter -le $END ]
do
ip=$BASE.$counter
if ping -qc 2 $ip
then
echo "$ip responds"
fi
counter=$(( $counter + 1 ))
done
ip neighbor
arp -a
Arpwatch
As other posters pointed out, nmap is the way to go, but here's how to do the equivalent of a ping scan in bash. I wouldn't use the broadcast ping, as a lot of systems are configured not to respond to broadcast ICMP nowadays.
for i in $(seq 1 254); do
host="192.168.100.$i"
ping -c 1 -W 1 $host &> /dev/null
echo -n "Host $host is "
test $? -eq 0 && echo "up" || echo "down"
done
#!/bin/bash
#Get the ip address for the range
ip=$(/sbin/ifconfig eth0 | grep 'inet addr:' | cut -d: -f2 | awk '{ print $1}' | cut -d"." -f1,2,3)
# ping test and list the hosts and echo the info
for range in $ip ; do [ $? -eq 0 ] && ping -c 1 -w 1 $range > /dev/null 2> /dev/null && echo "Node $range is up"
done
Although an old question, it still seems to be important (at least important enough for me to deal with this). My script relies on nmap too, so nothing special here except that ou can define which interface you want to scan and the IP Range is created automagically (at least kind of).
This is what I came up with
#!/bin/bash
#Script for scanning the (local) network for other computers
command -v nmap >/dev/null 2>&1 || { echo "I require nmap but it's not installed. Aborting." >&2; exit 1; }
if [ -n ""$#"" ]; then
ip=$(/sbin/ifconfig $1 | grep 'inet ' | awk '{ print $2}' | cut -d"." -f1,2,3 )
nmap -sP $ip.1-255
else
echo -e "\nThis is a script for scanning the (local) network for other computers.\n"
echo "Enter Interface as parameter like this:"
echo -e "\t./scannetwork.sh $(ifconfig -lu | awk '{print $2}')\n"
echo "Possible interfaces which are up are: "
for i in $(ifconfig -lu)
do
echo -e "\033[32m \t $i \033[39;49m"
done
echo "Interfaces which could be used but are down at the moment: "
for i in $(ifconfig -ld)
do
echo -e "\033[31m \t $i \033[39;49m"
done
echo
fi
One remark: This script is created on OSX, so there might be some changes to linux environments.
If you want to provide a list of hosts it can be done with nmap, grep and awk.
Install nmap:
$ sudo apt-get install nmap
Create file hostcheck.sh like this:
hostcheck.sh
#!/bin/bash
nmap -sP -iL hostlist -oG pingscan > /dev/null
grep Up pingscan | awk '{print $2}' > uplist
grep Down pingscan | awk '{print $2}' > downlist
-sP: Ping Scan - go no further than determining if host is online
-iL : Input from list of hosts/networks
-oG : Output scan results in Grepable format, to the given filename.
/dev/null : Discards output
Change the access permission:
$ chmod 775 hostcheck.sh
Create file hostlist with the list of hosts to be checked (hostname or IP):
hostlist (Example)
192.168.1.1-5
192.168.1.101
192.168.1.123
192.168.1.1-5 is a range of IPs
Run the script:
./hostcheck.sh hostfile
Will be generated files pingscan with all the information, uplist with the hosts online (Up) and downlist with the hosts offline (Down).
uplist (Example)
192.168.1.1
192.168.1.2
192.168.1.3
192.168.1.4
192.168.1.101
downlist (Example)
192.168.1.5
192.168.1.123
Some machines don't answer pings (e.g. firewalls).
If you only want the local network you can use this command:
(for n in $(seq 1 254);do sudo arping -c1 10.0.0.$n & done ; wait) | grep reply | grep --color -E '([0-9]+\.){3}[0-9]+'
Explanations part !
arping is a command that sends ARP requests. It is present on most of linux.
Example:
sudo arping -c1 10.0.0.14
the sudo is not necessary if you are root ofc.
10.0.0.14 : the ip you want to test
-c1 : send only one request.
&: the 'I-don't-want-to-wait' character
This is a really useful character that give you the possibility to launch a command in a sub-process without waiting him to finish (like a thread)
the for loop is here to arping all 255 ip addresses. It uses the seq command to list all numbers.
wait: after we launched our requests we want to see if there are some replies. To do so we just put wait after the loop.
wait looks like the function join() in other languages.
(): parenthesis are here to interpret all outputs as text so we can give it to grep
grep: we only want to see replies. the second grep is just here to highlight IPs.
hth
Edit 20150417: Maxi Update !
The bad part of my solution is that it print all results at the end. It is because grep have a big enough buffer to put some lines inside.
the solution is to add --line-buffered to the first grep.
like so:
(for n in $(seq 1 254);do sudo arping -c1 10.0.0.$n & done ; wait) | grep --line-buffered reply | grep --color -E '([0-9]+\.){3}[0-9]+'
#!/bin/bash
for ((n=0 ; n < 30 ; n+=1))
do
ip=10.1.1.$n
if ping -c 1 -w 1 $ip > /dev/null 2> /dev/null >> /etc/logping.txt; then
echo "${ip} is up" # output up
# sintax >> /etc/logping.txt log with .txt format
else
echo "${ip} is down" # output down
fi
done
The following (evil) code runs more than TWICE as fast as the nmap method
for i in {1..254} ;do (ping 192.168.1.$i -c 1 -w 5 >/dev/null && echo "192.168.1.$i" &) ;done
takes around 10 seconds, where the standard nmap
nmap -sP 192.168.1.1-254
takes 25 seconds...
Well, this is part of a script of mine.
ship.sh 🚢 A simple, handy network addressing 🔎 multitool with plenty of features 🌊
Pings network, displays online hosts on that network with their local IP and MAC address
It doesn't require any edit. Needs root permission to run.
GOOGLE_DNS="8.8.8.8"
ONLINE_INTERFACE=$(ip route get "${GOOGLE_DNS}" | awk -F 'dev ' 'NR == 1 {split($2, a, " "); print a[1]}')
NETWORK_IP=$(ip route | awk "/${ONLINE_INTERFACE}/ && /src/ {print \$1}" | cut --fields=1 --delimiter="/")
NETWORK_IP_CIDR=$(ip route | awk "/${ONLINE_INTERFACE}/ && /src/ {print \$1}")
FILTERED_IP=$(echo "${NETWORK_IP}" | awk 'BEGIN{FS=OFS="."} NF--')
ip -statistics neighbour flush all &>/dev/null
echo -ne "Pinging ${NETWORK_IP_CIDR}, please wait ..."
for HOST in {1..254}; do
ping "${FILTERED_IP}.${HOST}" -c 1 -w 10 &>/dev/null &
done
for JOB in $(jobs -p); do wait "${JOB}"; done
ip neighbour | \
awk 'tolower($0) ~ /reachable|stale|delay|probe/{printf ("%5s\t%s\n", $1, $5)}' | \
sort --version-sort --unique