Thread: Automatic IP change notifier

Hello everyone,

First of all thank you for reading this post!

Ok, here it goes:

What do I wanna create?
Answer: I want to create a bash script that checks my IP, and if there has been a change, send me an email, sms or automatically post the IP in a website.

Why should I? There are scripts such as no-ip.org, etc..
Answer: Even though I am using those as a guide, the truth is I want to make it better! Any help would be highly appreciated.

What have you done so far?
Answer: So far, this is all I got but it does not work!

#!/bin/bash
# The ultimate solution to my DNS problem
LOOKUP=`host subdomain.mydomain.com | awk '{print $4}'`
MYIP=`curl -s IP Chicken - What is my IP? Find Your IP Address! | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}'`
# Do the work
if [ "$LOOKUP" = "$MYIP" ]; then
echo "No change in your IP."
else
echo "The IP address has changed. "
#Either send me an: email, sms or post it in a site.
#mail -s "Here is the IP ... " username@mydomain.com
#echo `lynx -auth=${USERNAME}:${PASSWORD} -source "http://subdomain.mydomain.com"`
fi


What seems to be the problem is that the host command has some extra information that does not allow it to make a good comparison, so I always get the message that it has change.

Please help me out, I'm a quick learner!

~Saya

Hi,

Can you tell me what you are trying to achieve using above shell script? There may be better way exists to do the same thing. Is your IP changes everyday? DHCP ? Dynamic IP? Let me know

I have DHCP, so every day or so my IP changes.

But everytime is different, it can last me 2 days or it can last me 6 hours.

~Saya

P.D Thank you for the reply!

I have an adsl account that works through pppoe, this is my script:

Code:

#!/bin/bash
#set -x

IFACE=ppp0
EMAIL=you@domain
LOG=/your/log/path/ip

OLD_IP=`cat $LOG`

# get current ip on IFACE
    x=`/sbin/ifconfig $IFACE`
    y=${x#*inet addr:}
    y=${y%% *}

# log current ip
    echo $y > $LOG

# check if ip changed

    # if we have disconnected for a long time
    if [[ -z "$OLD_IP" ]] && [[ "$y" ]]; then

        # report new ip    
        echo 'New IP address for' `hostname` 'is:' $y 'on ' `date` | mail -s 'New IP' $EMAIL

    # if ip changed since last check
    elif [[ "$OLD_IP" ]] && [[ "$y" ]]; then

        if [ "$y" != "$OLD_IP" ]; then
        # report new ip    
        echo 'New IP address for' `hostname` 'is:' $y 'on ' `date` | mail -s 'New IP' $EMAIL
        fi
    fi

exit 0

run it every 5 minute via cron.

Thanks but I do not know if that script would work...

I am connected via router to the internet, it is not straight through.

Here is a copy of my ifconfig:

sayayinx@sayayinx:~$ ifconfig
eth0 Link encap:Ethernet HWaddr 00:E0:18:5A:G1:F0
inet addr:192.168.1.101 Bcast:255.255.255.255 Mask:255.255.255.0
inet6 addr: fe80::3e0:18ff:fe5a:c1f0/64 Scope:Link
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:31898184 errors:0 dropped:0 overruns:0 frame:0
TX packets:30138060 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:12692099512 (12.5 GiB) TX bytes:12820138230 (12.6 GiB)

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
inet6 addr: ::1/128 Scope:Host
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:10926 errors:0 dropped:0 overruns:0 frame:0
TX packets:10926 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:1583104 (1.5 MiB) TX bytes:1583104 (1.5 MiB)

Would it work?

Originally Posted by SAYAYINX

Thanks but I do not know if that script would work...

I am connected via router to the internet, it is not straight through.

...
Would it work?

No, it wont.
You should change the "get current ip on IFACE" section.

you can use some "what is my ip" web sites and grep your ip in html page, or if you have and site, web host available, write a simple php script to give JUST the visitor ip.

sample php code that should work:

PHP Code:

<?php echo getenv('REMOTE_ADDR'); ?>

I will use my line then:

MYIP=`curl -s IP Chicken - What is my IP? Find Your IP Address! | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}'`

I know it works.

But I have another question:

LOG=/your/log/path/ip <= where is that folder? can i make one up?

OLD_IP=`cat $LOG` <= again, is that a folder? a file?

Thanks for the quick reply

please wrap code with code tag! ([ code ] [ /code ] without space in bracket

Originally Posted by SAYAYINX

I will use my line then:

MYIP=`curl -s IP Chicken - What is my IP? Find Your IP Address! | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}'`
I know it works.

yes, this works, but this work better:

Code:

curl -s http://www.ipchicken.com/ | awk '/[0-9]*\.[0-9]*\.[0-9]*\.[0-9]*/ {print $1}' | uniq

Originally Posted by SAYAYINX

But I have another question:
LOG=/your/log/path/ip <= where is that folder? can i make one up?
OLD_IP=`cat $LOG` <= again, is that a folder? a file?

you should create the folder and enter full path here.
i have a 'scrpts' folder in my home director. and save log file with a 'log_' prefix with script name there.

ex:
script: /home/ali/scripts/ip_change
log file: /home/ali/scripts/log_ip_change

i have assigned the log file path to LOG variable in script, the in used 'LOG' variable as parameter to 'cat' command to read file content and assigned the result to 'OLD_IP' variable.

you just need to define 'LOG' variable. the LOG variable points to a file.

Ali_ix, nice script

BTW, welcome to forum!

Originally Posted by nixcraft

Ali_ix, nice script

BTW, welcome to forum!

Thanks Vivek