opening a port without root permission

opening a port without root permission

[Anshuman Singh Rawat]

Hi,
Is there any way one can open a port, in my specific case - the ARP port, so that I could do an Arping without a root access ? 

Or is there any way the root could give permission to a user to open a port ?

Or does anyone know a way by which I can extract the MAC address of a remote machine in a different subnet, where I do not have to be a super-user?

Any pointers would be greatly appreciated.
Thanks.

-Anshuman

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Re: opening a port without root permission

[Eric]

On Tuesday 29 June 2004 08:20 pm, Anshuman Singh Rawat wrote:
> Hi,
> Is there any way one can open a port, in my specific case - the ARP port,
> so that I could do an Arping without a root access ?
>
> Or is there any way the root could give permission to a user to open a port
> ?
>
> Or does anyone know a way by which I can extract the MAC address of a
> remote machine in a different subnet, where I do not have to be a
> super-user?
>
> Any pointers would be greatly appreciated.
> Thanks.

sudo

This program will allow root to give normal users "root" access to specified 
programs with or without a password.

To see if its already installed do 

"man sudo"
or
"visudo" 


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getting MAC addresses (was: Re: opening a port without root permission)

[Ray Olszewski]

At 09:20 PM 6/29/2004 -0400, Anshuman Singh Rawat wrote:
>Hi,
>Is there any way one can open a port, in my specific case - the ARP port, 
>so that I could do an Arping without a root access ?
>
>Or is there any way the root could give permission to a user to open a port ?
>
>Or does anyone know a way by which I can extract the MAC address of a 
>remote machine in a different subnet, where I do not have to be a super-user?
>
>Any pointers would be greatly appreciated.
>Thanks.

Others already suggested "sudo" as the way to deal with the arping problem. 
But... are you really able to use arping to get MAC addresses of hosts not 
on the Ethernet local to the host you arping from? (I assume that is what 
you mean by "in a different subnet".)

I was curious about this, so I tested it here. With the current Debian-Sid 
version of arping, arping'ing the IP address of a host on my DMZ from my 
LAN returns the MAC address of my router (since it does proxy arp), NOT the 
MAC address of the target host's own interface. If I arping the actual MAC 
address of the DMZ host (as shown in the arp table of my router), I get no 
response.

Am I missing something? I ask because this problem -- how to get the MAC 
address of a non-local host -- comes up again and again, and I always 
believed there was no solution to it (excluding ones that involve running 
some application on the target host). Am I mistaken?



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Re: getting MAC addresses (was: Re: opening a port without root permission)

[Eric]

On Wednesday 30 June 2004 11:39 am, Ray Olszewski wrote:
> At 09:20 PM 6/29/2004 -0400, Anshuman Singh Rawat wrote:
> >Hi,
> >Is there any way one can open a port, in my specific case - the ARP port,
> >so that I could do an Arping without a root access ?
> >
> >Or is there any way the root could give permission to a user to open a
> > port ?
> >
> >Or does anyone know a way by which I can extract the MAC address of a
> >remote machine in a different subnet, where I do not have to be a
> > super-user?
> >
> >Any pointers would be greatly appreciated.
> >Thanks.
>
> Others already suggested "sudo" as the way to deal with the arping problem.
> But... are you really able to use arping to get MAC addresses of hosts not
> on the Ethernet local to the host you arping from? (I assume that is what
> you mean by "in a different subnet".)
>
> I was curious about this, so I tested it here. With the current Debian-Sid
> version of arping, arping'ing the IP address of a host on my DMZ from my
> LAN returns the MAC address of my router (since it does proxy arp), NOT the
> MAC address of the target host's own interface. If I arping the actual MAC
> address of the DMZ host (as shown in the arp table of my router), I get no
> response.
>
> Am I missing something? I ask because this problem -- how to get the MAC
> address of a non-local host -- comes up again and again, and I always
> believed there was no solution to it (excluding ones that involve running
> some application on the target host). Am I mistaken?
>

As far as I know there is no way to get the MAC address across subnets. I 
believe the problem is the source MAC gets stripped off when it hits the 
router and the MAC of the router is used. This would be possible if you are 
on a *briged* network I believe, but there is little to no hope on a routed 
network.

Try telnet/ssh tot he remote and then ifconfig ;)
>
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Re: getting MAC addresses (was: Re: opening a port without root permission)

[Anshuman Singh Rawat]

> Others already suggested "sudo" as the way to deal with the arping 
> problem. 
> But... are you really able to use arping to get MAC addresses of 
> hosts not 
> on the Ethernet local to the host you arping from? (I assume that 
> is what 
> you mean by "in a different subnet".)
> 
> I was curious about this, so I tested it here. With the current 
> Debian-Sid 
> version of arping, arping'ing the IP address of a host on my DMZ 
> from my 
> LAN returns the MAC address of my router (since it does proxy 
> arp), NOT the 
> MAC address of the target host's own interface. If I arping the 
> actual MAC 
> address of the DMZ host (as shown in the arp table of my router), 
> I get no 
> response.
> 
> Am I missing something? I ask because this problem -- how to get 
> the MAC 
> address of a non-local host -- comes up again and again, and I 
> always 
> believed there was no solution to it (excluding ones that involve 
> running 
> some application on the target host). Am I mistaken?

Sorry. My mistake. It cant retrieve the MAC address of a machine on a different subnet.


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