Find the IP address of the client in an SSH session - linux

Question

I have a script that is to be run by a person that logs in to the server with SSH.
Is there a way to find out automatically what IP address the user is connecting from?
Of course, I could ask the user (it is a tool for programmers, so no problem with that), but it would be cooler if I just found out.

Answer 1

Check if there is an environment variable called:
$SSH_CLIENT
OR
$SSH_CONNECTION
(or any other environment variables) which gets set when the user logs in. Then process it using the user login script.
Extract the IP:
$ echo $SSH_CLIENT | awk '{ print $1}'
1.2.3.4
$ echo $SSH_CONNECTION | awk '{print $1}'
1.2.3.4

Answer 2

You could use the command:
server:~# pinky
that will give to you somehting like this:
Login Name TTY Idle When Where
root root pts/0 2009-06-15 13:41 192.168.1.133

Answer 3

Try the following to get just the IP address:
who am i|awk '{ print $5}'

Answer 4

Just type the following command on your Linux machine:
who

Answer 5

who | cut -d"(" -f2 |cut -d")" -f1

Answer 6

Improving on a prior answer. Gives ip address instead of hostname. --ips not available on OS X.
who am i --ips|awk '{print $5}' #ubuntu 14
more universal, change $5 to $6 for OS X 10.11:
WORKSTATION=`who -m|awk '{print $5}'|sed 's/[()]//g'`
WORKSTATION_IP=`dig +short $WORKSTATION`
if [[ -z "$WORKSTATION_IP" ]]; then WORKSTATION_IP="$WORKSTATION"; fi
echo $WORKSTATION_IP

Answer 7

who am i | awk '{print $5}' | sed 's/[()]//g' | cut -f1 -d "." | sed 's/-/./g'
export DISPLAY=`who am i | awk '{print $5}' | sed 's/[()]//g' | cut -f1 -d "." | sed 's/-/./g'`:0.0
I use this to determine my DISPLAY variable for the session when logging in via ssh and need to display remote X.

Answer 8

netstat -tapen | grep ssh | awk '{ print $4}'

Answer 9

A simple command to get a list of recent users logged in to the machine is last. This is ordered most recent first, so last | head -n 1 will show the last login. This may not be the currently logged in user though.
Sample output:
root pts/0 192.168.243.99 Mon Jun 7 15:07 still logged in
admin pts/0 192.168.243.17 Mon Jun 7 15:06 - 15:07 (00:00)
root pts/0 192.168.243.99 Mon Jun 7 15:02 - 15:06 (00:03)
root pts/0 192.168.243.99 Mon Jun 7 15:01 - 15:02 (00:00)
root pts/0 192.168.243.99 Mon Jun 7 13:45 - 14:12 (00:27)
root pts/0 192.168.243.99 Mon May 31 11:20 - 12:35 (01:15)
...

Answer 10

You can get it in a programmatic way via an SSH library (https://code.google.com/p/sshxcute)
public static String getIpAddress() throws TaskExecFailException{
ConnBean cb = new ConnBean(host, username, password);
SSHExec ssh = SSHExec.getInstance(cb);
ssh.connect();
CustomTask sampleTask = new ExecCommand("echo \"${SSH_CLIENT%% *}\"");
String Result = ssh.exec(sampleTask).sysout;
ssh.disconnect();
return Result;
}

Answer 11

an older thread with a lot of answers, but none are quite what i was looking for, so i'm contributing mine:
sshpid=$$
sshloop=0
while [ "$sshloop" = "0" ]; do
if [ "$(strings /proc/${sshpid}/environ | grep ^SSH_CLIENT)" ];
then
read sshClientIP sshClientSport sshClientDport <<< $(strings /proc/${sshpid}/environ | grep ^SSH_CLIENT | cut -d= -f2)
sshloop=1
else
sshpid=$(cat /proc/${sshpid}/status | grep PPid | awk '{print $2}')
[ "$sshpid" = "0" ] && sshClientIP="localhost" && sshloop=1
fi
done
this method is compatible with direct ssh, sudoed users, and screen sessions. it will trail up through the process tree until it finds a pid with the SSH_CLIENT variable, then record its IP as $sshClientIP. if it gets too far up the tree, it will record the IP as 'localhost' and leave the loop.

Answer 12

I'm getting the following output from who -m --ips on Debian 10:
root pts/0 Dec 4 06:45 123.123.123.123
Looks like a new column was added, so {print $5} or "take 5th column" attempts don't work anymore.
Try this:
who -m --ips | egrep -o '([0-9]{1,3}\.){3}[0-9]{1,3}'
Source:
#Yvan's comment on #AlexP's answer
#Sankalp's answer

Answer 13

netstat -tapen | grep ssh | awk '{ print $10}'
Output:
two # in my experiment
netstat -tapen | grep ssh | awk '{ print $4}'
gives the IP address.
Output:
127.0.0.1:22 # in my experiment
But the results are mixed with other users and stuff. It needs more work.

Answer 14

Assuming he opens an interactive session (that is, allocates a pseudo terminal) and you have access to stdin, you can call an ioctl on that device to get the device number (/dev/pts/4711) and try to find that one in /var/run/utmp (where there will also be the username and the IP address the connection originated from).

Answer 15

Usually there is a log entry in /var/log/messages (or similar, depending on your OS) which you could grep with the username.

Answer 16

netstat will work (at the top something like this)
tcp 0 0 10.x.xx.xx:ssh someipaddress.or.domainame:9379 ESTABLISHED

Answer 17

Linux: who am i | awk '{print $5}' | sed 's/[()]//g'
AIX: who am i | awk '{print $6}' | sed 's/[()]//g'

Answer 18

Search for SSH connections for "myusername" account;
Take first result string;
Take 5th column;
Split by ":" and return 1st part (port number don't needed, we want just IP):
netstat -tapen | grep "sshd: myusername" | head -n1 | awk '{split($5, a, ":"); print a[1]}'
Another way:
who am i | awk '{l = length($5) - 2; print substr($5, 2, l)}'

Answer 19

One thumb up for #Nikhil Katre's answer :
Simplest command to get the last 10 users logged in to the machine is last|head.
To get all the users simply use last command
The one using who or pinky did what is basically asked. But But But they don't give historical sessions info.
Which might also be interesting if you want to know someone who has just logged in and
logged out already when you start this checking.
if it is a multiuser system. I recommand add the user account you are looking for:
last | grep $USER | head
EDIT:
In my case, both $SSH_CLIENT and $SSH_CONNECTION do not exist.