Script to get Client Table from Router

Nmap will do it well.

Does your router not renew the same IP to the same name? Never seen a router not do that.... Weird.

On 06/19/14 15:16, actionparsnip wrote:
> Your question #250484 on Ubuntu changed:
> https://answers.launchpad.net/ubuntu/+question/250484
>
> Status: Open => Answered
>
> actionparsnip proposed the following answer:
> Nmap will do it well.

Unless I, and several others, missed something, map will not return host
names!

Tom Dean

On 06/19/14 15:16, actionparsnip wrote:

> Does your router not renew the same IP to the same name? Never seen a
> router not do that.... Weird.
>

The router does allocate the same IP to the same name, the setting is
for leases to never expire, or, at least for a very long time.

Today, for example, there are two new computers on the network. They
will be here over the weekend.

To handle them, I used a browser, connected to the router, cut-paste the
client list into emacs and saved the file. Then, a script to update
etc/hosts. Copy the file to several machines and update etc/hosts.
Then, all is ready to go.

I do this several times a month.

Tom Dean

On 06/20/14 01:21, actionparsnip wrote:

> actionparsnip proposed the following answer:
> sudo nmap −sP −R 192.168.0.0/24

Thank you. Thank you. This helps a lot.

My version of nmap, uses -sn rather than -sP

 > nmap --version
Nmap version 6.40 ( http://nmap.org )
Platform: x86_64-pc-linux-gnu
Compiled with: liblua-5.2.3 openssl-1.0.1f libpcre-8.31 libpcap-1.5.3
nmap-libdnet-1.12 ipv6
Compiled without:
Available nsock engines: epoll poll select

Tom Dean

Thanks actionparsnip, that solved my question.

On 06/20/14 10:32, tomdean wrote:

Oopos. I forgot I had updated etc/hosts.

nmap reads the host names from etc/hosts, I believe.

With hostnames in etc/hosts:

 > nmap -sP -R 192.168.2.0/24
Starting Nmap 6.40 ( http://nmap.org ) at 2014-06-20 10:02 PDT
Nmap scan report for router.yyyyy (192.168.2.1)
Host is up (0.00057s latency).
Nmap scan report for android_xxxx (192.168.2.2)
Host is up (0.097s latency).
Nmap scan report for android_xxxx (192.168.2.5)
Host is up (0.10s latency).
Nmap scan report for P9X79.yyyyy (192.168.2.7)
Host is up (0.00013s latency).
Nmap scan report for android-xxxxx (192.168.2.8)
Host is up (0.15s latency).
Nmap scan report for android-xxxxx (192.168.2.9)
Host is up (0.19s latency).
Nmap scan report for zd7000.yyyyy (192.168.2.10)
Host is up (0.0022s latency).
Nmap done: 256 IP addresses (7 hosts up) scanned in 21.46 seconds

With NO hostnames in etc/hosts
 > nmap -sP -R 192.168.2.0/24
Starting Nmap 6.40 ( http://nmap.org ) at 2014-06-20 10:37 PDT
Nmap scan report for router.yyyyy (192.168.2.1)
Host is up (0.00056s latency).
Nmap scan report for 192.168.2.2
Host is up (0.10s latency).
Nmap scan report for 192.168.2.5
Host is up (0.099s latency).
Nmap scan report for 192.168.2.7
Host is up (0.00011s latency).
Nmap scan report for 192.168.2.8
Host is up (0.18s latency).
Nmap scan report for 192.168.2.9
Host is up (0.19s latency).
Nmap scan report for 192.168.2.10
Host is up (0.0013s latency).
Nmap done: 256 IP addresses (7 hosts up) scanned in 36.79 seconds