[j-nsp] juniper switch ex2200 how to find port from ip address?

[Jed Laundry]

Just to throw it out there, I created the attached op script a while ago to
do this in a small office environment. It does require having a family inet
address on the switch (so don't forget your firewall filters to prevent
cross-vlan contamination!)

Next on my todo list was for it to run through a list of switches running
the get-ethernet-switching-table-information remotely, so that it could be
used on a larger LAN without inet addressing each switch. And inet6, of
course.

Thanks,
Jed.




On 27 August 2014 01:31, Per Granath <per.granath at gcc.com.cy> wrote:

> This might be interesting: http://youtu.be/Le9S2rj_qXI?t=19m46s (starting
> from 19m and 46s into the video).
>
>
> -----Original Message-----
> From: juniper-nsp [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf
> Of Evangelos Kanarelis
> Sent: Tuesday, August 26, 2014 3:43 PM
> To: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] juniper switch ex2200 how to find port from ip
> address?
>
> This has now been resolved.
>
> Managed to get access to the core switch and used the arp table.
>
> Thank you all for your help :-)
>
> Angelo Kanarelis
> Infrastructure Support Engineer
>
>
>
> T: +44 (0) 207 421 2575  M: +44(0) 779 5613721 2nd Floor, Nexus Place, 25
> Farringdon Street, London, EC4A4AB
>
>
> -----Original Message-----
> From: juniper-nsp [mailto:juniper-nsp-bounces at puck.nether.net] On Behalf
> Of Phil Mayers
> Sent: 26 August 2014 13:06
> To: juniper-nsp at puck.nether.net
> Subject: Re: [j-nsp] juniper switch ex2200 how to find port from ip
> address?
>
> On 26/08/14 12:22, Evangelos Kanarelis wrote:
> > Hello everybody
> >
> > I am relatively new to networking and I am currently managing a few
> > EX2200 switches.
> >
> > I need to find to which port a machine is connected to, but all I have
> > is an IP Address. I know that I can use show ethernet-switching table
> > brief but unfortunately I do not have the MAC address.
> >
> > Any help would be greatly appreciated.
>
> When you have time, consider looking into running something like Netdisco
> against your switches and routers.
>
> Without a MAC, it's not straightforward.
>
> It's not really difficult either, but if you're new to networking all the
> suggestions I can think of (put an IP address on the ports vlan, ping the
> host, look in the ARP table; put a logging firewall filter in, look for
> matches; enable DHCP/ARP snooping) carry a risk of breaking things.
>
> It would be a lot easier if you could find the MAC address from the
> router. Can you really not do that?
>
> Or if you can get to the host, just unplug then re-attach the host, then
> look in the switch logs for which port just came up.
>
> If not, the "safest" thing is probably to modify the switch to have an IP
> address on the port VLAN and ping the host, then find the MAC from the ARP
> table like so:
>
> == Add the IP to the vlan ==
>
> configure
> set vlan <name> l3-interface vlan.<tag>
> set interfaces vlan unit <tag> family inet address <ip/mask> commit
>
> == Find the IP/MAC/port ==
>
> run ping <ip> count 1
> run show arp no-resolve hostname <ip>
> run show ethernet-switching table | match <MAC from the ARP output>
>
> == Undo adding the IP
>
> rollback 1
> commit
>
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