I have a debian installation using eth0 and wlan0.
For all applications I want to use eth0 except for one single script I want to use wlan0.
Is there any possibility to force for example in a terminal session or in e.g. a shell script the usage of wlan0 for this specific script?
Thanks a lot for your help
Yes, it is quite easy to use eth0 by default and then if you need to use wlan0 for one run simply pass wlan0 as a command-line argument. You should also check that the value you are using is either eth0 or wlan0, or you should consider the argument invalid.
A short script that implements that logic would be:
#!/bin/sh
iface=${1:-eth0} ## use eth0 by default or use the first argument
## if the iface entered is not eth0 or wlan0, handle error
if [ "$iface" != "eth0" ] && [ "$iface" != "wlan0" ]
then
printf "error: invalid interface '%s'\n" "$iface"
exit 1
fi
printf "using: %s\n" "$iface" ## output interface being used
Example Use/Output
$ sh useiface.sh
using: eth0
$ sh useiface.sh wlan0
using: wlan0
$ sh useiface.sh eth1
error: invalid interface 'eth1'
You can see above when the user attempts to call the script with eth1 that is not considered valid and the script provides an error and exits. You can adjust to fit your needs.
I would like to trigger a service when a change of an ip address on a specific interface occurs. Is there a target for this or some other method I am not aware of to achieve this using systemd on Linux (Kernel 3.19)?
The service would be used to send a SIGNAL to a defined process. The Linux is running on an embedded system.
Thanks!
Because you use Systemd you might already use systemd-networkd for managing your devices instead of relying on 3rd party code.
You could use the structured journal output to get the last 2 ADDRESS field of the current BOOD_ID.(sadly, there is no notification mechanism for address changes in systemd-networkd):
→ sudo journalctl -F ADDRESS -u systemd-networkd -n 2
192.168.178.29
So, if there is only one line output, there was no address change.
There is an solution in other question of StackOverflow. Just here:
Detecting a change of IP address in Linux
I like this code, it's easy, you onli need a cron job with frecuency as you need (I made a little change):
#!/bin/bash
OLD_IP=`cat ip.txt`
NEW_IP=`/sbin/ifconfig | awk -F "[: ]+'{ print $4}'`
if [ $NEW_IP != OLD_IP ]; then
YOU_COMMAND <commands>
echo $NEW_IP > ip.txt
fi
exit 0
I am trying to get this function to file .bashrc
This is my function :
function my_ip() {
echo "internal or external?"
read -r choise
if [ "$choise" == "internal" ] ;then
echo "please enter the name of the card that youare using at";
read -r card ;
ifconfig "$card" | grep 'inet addr' |cut -d':' -f2|cut -d ' ' -f1;
else
wget -qO- http://noc.co.il |grep "var VisitorCountry" | awk '{print$4}'|cut -d '"' -f4;
fi
}
My goal is that the function will quickly give me my IP by choosing internal or external
if I want to automatically displays the network card ("without the need to ask Which network card do you use(The computer automatically detects which network card the user uses and will put the name as a variable at the right commend for internal IP , how can I get him to identify what card the user use(WLAN0 WLAN1 etc.) ?
A system can have more than one IP address. Which one of them is the one you are looking for? You did not specify that.
There are multiple questions related to finding IP addresses with bash:
Find internal IP address
The accepted answer uses a deprecated option for hostname; the second answer is the more correct one IMHO.
In bash, is there a way to find the IP address for all interfaces?
Find IP address for my system
Bash script to find all IP addresses
If none of those float your boat, consider closing this question and posting a new one with more precise phrasing what you are looking for.
I want command to get Linux machine(amazon) external/public IP Address.
I tried hostname -I and other commands from blogs and stackoverflow like
ifconfig | sed -En 's/127.0.0.1//;s/.*inet (addr:)?(([0-9]*\.){3}[0-9]*).*/\2/p'
and many more. But they all are giving me internal IP Address.
Then I found some sites which provides API for this.
Example : curl http://ipecho.net/plain; echo
But I don't want to rely on third party website service. So, is there any command line tool available to get external IP Address?
simplest of all would be to do :
curl ifconfig.me
A cleaner output
ifconfig eth0 | awk '/inet / { print $2 }' | sed 's/addr://'
You could use this script
# !/bin/bash
#
echo 'Your external IP is: '
curl -4 icanhazip.com
But that is relying on a third party albeit a reliable one.
I don't know if you can get your external IP without asking someone/somesite i.e. some third party for it, but what do I know.
you can also just run:
curl -4 icanhazip.com
This is doing the same thing as a command the -4 is to get the output in Ipv4
You can use this command to get public ip and private ip(second line is private ip; third line is public ip.)
ip addr | awk '/inet / {sub(/\/.*/, "", $2); print $2}'
I would suggest you to use the command external-ip (sudo apt-get install miniupnpc) as it (I'm almost sure) uses upnp protocol to ask the router instead of asking an external website so it should be faster, but of course the router has to have upnp enabled.
You can simply do this :
curl https://ipinfo.io/ip
It might not work on amazon because you might be using NAT or something for the server to access the rest of the world (and for you to ssh into it also). If you are unable to ssh into the ip that is listed in ifconfig then you are either in a different network or dont have ssh enabled.
This is the best I can do (only relies on my ISP):
ISP=`traceroute -M 2 -m 2 -n -q 1 8.8.8.8 | grep -m 1 -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'`
extIP=`ping -R -c 1 -t 1 -s 1 -n $ISP | grep RR | grep -m 1 -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'`
echo $extIP
Or, the functionally same thing on one line:
ISP=`traceroute -M 2 -m 2 -n -q 1 8.8.8.8 | grep -m 1 -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'` | ping -R -c 1 -t 1 -s 1 -n $ISP | grep RR | grep -m 1 -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
to save it to a temporary & hidden file add > .extIP to the end of the last line, then cat .extIP to see it.
If your ISP's address never changes (honestly i'm not sure if it would or not), then you could fetch it once, and then replace $ISP in line two with it
This has been tested on a mac with wonderful success.
the only adjustment on linux that I've found so far is the traceroute "-M" flag might need to be "-f" instead
and it relies heavily on the ping's "-R" flag, which tells it to send back the "Record Route" information, which isn't always supported by the host. But it's worth a try!
the only other way to do this without relying on any external servers is to get it from curl'ing your modem's status page... I've done this successfully with our frontier DSL modem, but it's dirty, slow, unreliable, and requires hard-coding your modem's password.
Here's the "process" for that:
curl http://[user]:[password]#[modem's LAN address]/[status.html] | grep 'WanIPAddress =' | grep -m 1 -Eo '[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}'
That fetches the raw html, searches for any lines containing "WanIpAddress =" (change that so it's appropriate for your modem's results), and then narrows down those results to an IPv4 style address.
Hope that helps!
As others suggested, we have to rely on third party service which I don't feel safe using it. So, I have found Amazon API on this answer :
$ curl http://169.254.169.254/latest/meta-data/public-ipv4
54.232.200.77
For more details, https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-instance-metadata.html#instancedata-data-retrieval
The super-easy way is using the glances tool. you can install it on Ubuntu using:
$ sudo apt install glances
then using it with:
$ glances
and at the top of the terminal, it highlights your public IP address, and so many other information about your system (like what htop does) and network status.
For a formatted output use :-
dig TXT +short o-o.myaddr.l.google.com #ns1.google.com
it'll give you formatted output like this
"30.60.10.11"
also FYI,
dig is more faster than curl and wget
The following works as long as you have ifconfig and curl.
curl ifconfig.me
I need a Bash (or a plain shell) script to put in a cronjob that every minute checks if the Internet is up.
This is how I did it:
#! /bin/sh
host1=google.com
host2=wikipedia.org
curr_date=`date +"%Y%m%d%H%M"`
echo -n "${curr_date};"
((ping -w5 -c3 $host1 || ping -w5 -c3 $host2) > /dev/null 2>&1) &&
echo "up" || (echo "down" && exit 1)
How would you do it? Which hosts would you ping?
Clarifications:
By "internet is up", I mean my internet connection.
By "up", I mean to have usable connection (doesn't really matter if we are talking about the DNS being down or the connection is really really slow [mind the -w for timeout]). That is also why I didn't include any IP but only hosts.
Should I also ping Stack Overflow? I mean, if I can't access Google, Wikipedia or Stack Overflow, I don't want Internet :p
That one seems like a good solution. Just add a few more hosts, and maybe some pure IP hosts so you don't rely on DNS functioning (which in itself depends on your definition of "up").
Thanks for your code, it works great, I've left only one line actually:
((ping -w5 -c3 8.8.8.8 || ping -w5 -c3 4.2.2.1) > /dev/null 2>&1) && echo "up" || (echo "down" && exit 1)
What portion of Internet connectivity are you looking to check? DHCP? DNS? Physically being plugged into a jack? Kernel recognizing the presence of the NIC?
You can manually query your ISP's DNS server(s) by using the host(1) command. This is generally a good indication of whether your router has lost its connection to the ISP.
You can query what interfaces your kernel has by using netstat(8) or ifconfig(8).
You can get detailed statistics about the interface using ifstat.