How to get IP of computer assigned by DHCP?

Thread Tools Search this Thread
Special Forums IP Networking How to get IP of computer assigned by DHCP?
# 1  
Old 01-13-2014
How to get IP of computer assigned by DHCP?

I have a computer at work with no control over the network settings. We have to pay for a static IP so that won't happen. I'm running an SSH server so I can connect back and analyze data when I'm sitting in boring classes.

I want to know how to get the IP of this machine when I'm on the same network.

Previously what I would do is either grab it before I leave the office, or I set up a script in mail that would email me the IP address if I sent a very specific e-mail to myself.

I'm not very good with networking, and to make matters worse, I'm on an iPad with no true access to a console.

No, this is not illegal, I'm friends with the IT guy on the floor, and he says it's perfectly fine. However, I don't think running a network scan would go unnoticed.

So, what is the best way to do this? My e-mail script only works if the computer isn't asleep, and it especially doesn't work if I forget what to e-mail myself.

Any help?

I could potentially connect to my home server, VPN into the network, then run a bash script that looks for my server but... I don't think that's a great idea.
# 2  
Old 01-13-2014
if the computer isn't asleep
I'm not really sure what this bit means. Why would it be asleep? Are you thinking of a Windoze server hibernating?

Try ifconfig -a or get the output of hostname and from your remote client, use nslookup the-hostname or even just ssh the-hostname

Does that help, or have I missed the point somewhere?

# 3  
Old 01-14-2014
You could use a free DDNS service and register the ip you get served during DHCP...then you should not care about the actual IP.
# 4  
Old 01-14-2014
If you're looking for the external IP, yes, dynamic DNS is a good way to do this. You can use a free DNS service like, to host a URL like, and run an updater client on your computer to keep pointing to the correct IP. There might be an occasional bit of lag between IP and DNS but it's pretty good for the most part. This is how we manage our crummy ISP's IP at work.

Of course, nothing's going to work if your computer's asleep!

Last edited by Corona688; 01-14-2014 at 11:52 AM..
# 5  
Old 01-14-2014
Maybe you can get your work computer's IP and host name with
host `hostname`

getent hosts `hostname`

Then you can pipe this to mail, for example
host `hostname` | mail yourmail@youraddress

# 6  
Old 01-15-2014
I think if I "ssh 'hostname" that might work. I guess I could check through the vpn.

For those of you confused here is what's going on.

I have a Mac desktop that I use for my day to day work. Sometimes I want to ssh into it from my iPad over wifi to do some data analysis, so I have an ssh server running. Just the standard ssh server that ships with os X, nothing special. Only I have permission etc.

However, the intranet at work is DHCP based. I cannot request a static IP because it costs money (stupid I know.)

Sometimes I forget to grab my IP before I leave the office, so if I want to ssh into the computer I can't, because of DHCP. So my original question was what is the best way to get that IP if I am not currently in front of the computer.

I did not know you could use the hostname of a computer as the address essentially. As I stated before, I'm terrible at networking.

With that said, it iSSH on the ipad does not like using the hostname over a VPN (I'm testing it from home currently), but using the IP works perfectly.

Putty on XP says "host does not exist" when connected through the VPN even when I copy and paste the hostname from the result of the "hostname" command. Putting the IP into putty works just fine.

---------- Post updated 01-15-14 at 12:34 PM ---------- Previous update was 01-14-14 at 10:08 PM ----------

Sorry for the double post, I thinking I found some more hints about my problem.

My ip when I'm on the wireless network is aaa.bbb.100.### and the ip of the server is aaa.bbb.185.### where aaa and bbb are the same. So, in my limited knowledge of networking, I'd say that whenever I feed my ipad a hostname to try to connect to, it doesn't know where it is because it's on a slightly different network, but when I give it an ip, the ipad knows exactly where to look for the computer to find it.

I think I may be able to fix it by adding another DNS server in my network settings? But I don't know what to put. Or it has something to do with the hostname. The hostname I am using is something-computer.local. Can the .local be changed to tell the ipad to look somewhere else?

Last edited by corrado33; 01-14-2014 at 10:18 PM..
# 7  
Old 01-15-2014
Originally Posted by corrado33
So my original question was what is the best way to get that IP if I am not currently in front of the computer.
We know, and gave several answers.

Dynamic DNS remains a good option I think. It amounts to leaving a little client program running on your computer to update the IP address points to, where is a free domain name hosted by no-ip. There are many free services like this for exactly this purpose.
Login or Register to Ask a Question

Previous Thread | Next Thread

10 More Discussions You Might Find Interesting

1. IP Networking

Get DHCP relay interfaces IP address using DHCP

Hi All , please view the set up below: ------------------------------------------------------------------- | DHCP Server |-----------| ROUTER & |-----------| Clients | | | - -<eth1>| DHCP-RELAY|<eth2>-- | 192.168.88.X | ... (2 Replies)
Discussion started by: gdangoor
2 Replies

2. UNIX for Dummies Questions & Answers

How do you check if a variable has been assigned?

I am trying to check whether a variable has been assigned on the command line or not. Here is what I did: #!/usr/bin/bash if( $variable == '\0') { print "variable was not assigned" exit } else NF = 2 {print $1, ""} exit fi awk -f question1.awk variable = 58 letters.txt. So... (3 Replies)
Discussion started by: Fred63528
3 Replies

3. Shell Programming and Scripting

[Bash] Variable won't get assigned value

I am making of a script that will go through a couple of for loops and create file names based on the values in that loop, however the variable that combines everything is not getting assigned properly: #! /bin/bash for imod in K33_j1b_WS9_6 do for emod in mb2A mb2C mb3A mb3C mb4A... (1 Reply)
Discussion started by: badinsults
1 Replies

4. Shell Programming and Scripting

Curly braces assigned to variables

Hi, Im pretty new to Unix. I came across a script which was using PLSQL inside a script and there was an unusual thing mentioned. there was a variable assigned as P_CUR=${1} and one more as V_TAGFILE="$1" Couldnt find the difference. Also the variables were used in PLSQL... (1 Reply)
Discussion started by: njks68
1 Replies

5. Red Hat

Which IPs from the range are assigned to DHCP enabled clients

Hi All dhcpd.conf has a range of IPs sa for example( So this is the range of IP addresses the server will issue to DHCP enabled PC clients booting up on the network How do i know which IPs are being used or which IPs from the range are assigned to dhcp enabled... (11 Replies)
Discussion started by: tannu
11 Replies

6. Shell Programming and Scripting

Check if a variable has a value assigned?

Hi, I want to check if a variable has a value assigned to it or not. I can do following - cat $Var > File1 if then echo "$Var has value" else echo "$Var is null" fi But I have to check for 3 Variables and I want to wrap it up in couple of unix statements. Any... (3 Replies)
Discussion started by: sumeet
3 Replies

7. Shell Programming and Scripting

how to remove the assigned value from the string

Hi I have the following assignment in my ksh script: PX_LIST="4119 2390 2294 2776 2897 4099" Is there any sed/awk command which would allow the to remove certain number from this string. Let's say I need to remove PX=2390 from PX_LIST, so the output after deletion will be" PX_LIST="4119 2294... (5 Replies)
Discussion started by: aoussenko
5 Replies

8. Solaris

Unix terminal re-assigned with wrong IP address from window's DHCP

Hi all, I have this problem that puzzles me, i have setup all the right DHCP configuration in Windows Server. The reservation IP address in windows for this specific unix terminal. However, when i rebooted the unix terminal the IP which was already assigned for this box somehow change to a total... (0 Replies)
Discussion started by: tlee
0 Replies

9. UNIX for Dummies Questions & Answers

What does $? mean when assigned to a variable?

If i write this statement in a Korn Shell script RCODE=$? what possibly does it eman? (3 Replies)
Discussion started by: ranjita.c
3 Replies

10. AIX

Re: User assigned to privileged group

Hi! I need to know what is the risk involved if a user with UID >100 is attached to a group with gid =1 .i.e., a user is attached to a priviliged group in AIX . Kindly let me know what security implication can arise in this case? Early reply in this regard will be highly appreciated. (1 Reply)
Discussion started by: faraz82
1 Replies
Login or Register to Ask a Question