Networking Forums

Networking Forums > Network Hardware > Network Routers > Unknown host in my router's DHCP client list

Reply
Thread Tools Display Modes

Unknown host in my router's DHCP client list

 
 
Michel S.
Guest
Posts: n/a

 
      07-09-2007, 12:02 PM
Hello !

I have a small home network (3 PC's), all connected with cables to a
D-Link DI-624 router.

Each PC is configured in the router's DHCP with a static address.

From time to time, a friend's come home and connects to the lan either
with a cable, or with it's wireless adapter. In this latter case, I
set the WiFi radio on. (Otherwise, it is always set to "off").

Lately, I noticed a strange thing :

In my router's DHCP dynamic client list, there's an "unknown" host
listed. Unknown is both the host name and unknown to me.. The MAC
address doesn't match with one of my pc's nor with my friend's one.

Even if I shut down all but one of my pc's and reboot my router, this
unknown client appears in the DHCP client list a few seconds later -
with a lease expiring exactly one week from the moment I rebooted the
router.

I checked twice that my wireless radio was off.

I do not use networked devices such as a stand alone printer with it's
own print server.


Any idea ?


 
Reply With Quote
 
 
 
 
bearclaw@cruller.invalid
Guest
Posts: n/a

 
      07-10-2007, 12:21 PM
In article <(E-Mail Removed)>,
Michel S. <(E-Mail Removed)> wrote:

> Hello !
>
> I have a small home network (3 PC's), all connected with cables to a
> D-Link DI-624 router.
>
> Each PC is configured in the router's DHCP with a static address.
>
> From time to time, a friend's come home and connects to the lan either
> with a cable, or with it's wireless adapter. In this latter case, I
> set the WiFi radio on. (Otherwise, it is always set to "off").
>
> Lately, I noticed a strange thing :
>
> In my router's DHCP dynamic client list, there's an "unknown" host
> listed. Unknown is both the host name and unknown to me.. The MAC
> address doesn't match with one of my pc's nor with my friend's one.
>
> Even if I shut down all but one of my pc's and reboot my router, this
> unknown client appears in the DHCP client list a few seconds later -
> with a lease expiring exactly one week from the moment I rebooted the
> router.
>
> I checked twice that my wireless radio was off.
>
> I do not use networked devices such as a stand alone printer with it's
> own print server.
>
>
> Any idea ?


Are you using VOIP service?
 
Reply With Quote
 
 
 
 
bearclaw@cruller.invalid
Guest
Posts: n/a

 
      07-10-2007, 12:33 PM
In article <(E-Mail Removed)>,
Michel S. <(E-Mail Removed)> wrote:

> Hello !
>
> I have a small home network (3 PC's), all connected with cables to a
> D-Link DI-624 router.
>
> Each PC is configured in the router's DHCP with a static address.
>
> From time to time, a friend's come home and connects to the lan either
> with a cable, or with it's wireless adapter. In this latter case, I
> set the WiFi radio on. (Otherwise, it is always set to "off").
>
> Lately, I noticed a strange thing :
>
> In my router's DHCP dynamic client list, there's an "unknown" host
> listed. Unknown is both the host name and unknown to me.. The MAC
> address doesn't match with one of my pc's nor with my friend's one.
>
> Even if I shut down all but one of my pc's and reboot my router, this
> unknown client appears in the DHCP client list a few seconds later -
> with a lease expiring exactly one week from the moment I rebooted the
> router.
>
> I checked twice that my wireless radio was off.
>
> I do not use networked devices such as a stand alone printer with it's
> own print server.
>
>
> Any idea ?


Does the router issue an IP address to unknown? If so, is it in the
router's IP range (usually 192.68.x.xxx)? What operating system are you
using on your computer?

I think your question is a good one, because I have also seen mysterious
clients show up in router device lists without explanation. Not always
over wireless connections, either. Usually the whole thing becomes
apparent after a little investigation, though.

If the client shows up while the wireless function is disabled, it must
be something hardwired to the router. Clear the connected devices list,
disable wireless and use only your computer. See if the device shows up
again under those conditions. If it does, the culprit is your computer
(perhaps mis-identifying itself to the router's DHCP server).
 
Reply With Quote
 
John Dulak
Guest
Posts: n/a

 
      07-10-2007, 04:15 PM
(E-Mail Removed)lid wrote:
> In article <(E-Mail Removed)>,
> Michel S. <(E-Mail Removed)> wrote:
>
>> Hello !
>>
>> I have a small home network (3 PC's), all connected with cables to a
>> D-Link DI-624 router.
>>
>> Each PC is configured in the router's DHCP with a static address.
>>
>> From time to time, a friend's come home and connects to the lan either
>> with a cable, or with it's wireless adapter. In this latter case, I
>> set the WiFi radio on. (Otherwise, it is always set to "off").
>>
>> Lately, I noticed a strange thing :
>>
>> In my router's DHCP dynamic client list, there's an "unknown" host
>> listed. Unknown is both the host name and unknown to me.. The MAC
>> address doesn't match with one of my pc's nor with my friend's one.
>>
>> Even if I shut down all but one of my pc's and reboot my router, this
>> unknown client appears in the DHCP client list a few seconds later -
>> with a lease expiring exactly one week from the moment I rebooted the
>> router.
>>
>> I checked twice that my wireless radio was off.
>>
>> I do not use networked devices such as a stand alone printer with it's
>> own print server.
>>
>>
>> Any idea ?

>
> Does the router issue an IP address to unknown? If so, is it in the
> router's IP range (usually 192.68.x.xxx)? What operating system are you
> using on your computer?
>
> I think your question is a good one, because I have also seen mysterious
> clients show up in router device lists without explanation. Not always
> over wireless connections, either. Usually the whole thing becomes
> apparent after a little investigation, though.
>
> If the client shows up while the wireless function is disabled, it must
> be something hardwired to the router. Clear the connected devices list,
> disable wireless and use only your computer. See if the device shows up
> again under those conditions. If it does, the culprit is your computer
> (perhaps mis-identifying itself to the router's DHCP server).


Bearclaw:

Could it be that the WiFi interface is treated by the router just like
a NIC and is assigned an IP address?

I have a wired router with a WIFI access point connected to one of the
router's wired ports. If the access point is NOT powered on, only
wired connections show up in the router's DHCP client list. However,
if I apply porew to the access point it shows up in the DHCP client
list with its own MAC address and is assigned an IP address.

John


--
\\\||///
------------------o000----(o)(o)----000o----------------
----------------------------()--------------------------
'' Madness takes its toll - Please have exact change. ''

John Dulak - Gnomeway Services - http://tinyurl.com/2qs6o6
 
Reply With Quote
 
bearclaw@cruller.invalid
Guest
Posts: n/a

 
      07-11-2007, 06:12 AM
In article <igOki.7345$MV6.3279@trnddc01>,
John Dulak <(E-Mail Removed)> wrote:

> Could it be that the WiFi interface is treated by the router just like
> a NIC and is assigned an IP address?


Well, not that I've ever seen. DHCP servers must be queried before
issuing an IP, AFAIK. NICs just provide the interface, they don't
actually need IPs. As I understand the OP, some device is requesting an
IP even when the router's wireless function is disabled.

> I have a wired router with a WIFI access point connected to one of the
> router's wired ports. If the access point is NOT powered on, only
> wired connections show up in the router's DHCP client list. However,
> if I apply porew to the access point it shows up in the DHCP client
> list with its own MAC address and is assigned an IP address.


Your WAP is acting just like any other client on the router's LAN. I'm
guessing that any bridge or switch on the LAN would also require an IP
address in order to function properly.
 
Reply With Quote
 
John Dulak
Guest
Posts: n/a

 
      07-11-2007, 12:29 PM
(E-Mail Removed)lid wrote:
> In article <igOki.7345$MV6.3279@trnddc01>,
> John Dulak <(E-Mail Removed)> wrote:
>
>> Could it be that the WiFi interface is treated by the router just like
>> a NIC and is assigned an IP address?

>
> Well, not that I've ever seen. DHCP servers must be queried before
> issuing an IP, AFAIK. NICs just provide the interface, they don't
> actually need IPs. As I understand the OP, some device is requesting an
> IP even when the router's wireless function is disabled.
>


Bearclaw:

I understand that the NIC is just hardware and there must be software
to request an IP address from the DHCP server. The wireless portion of
the router must have SOME software associated specifically with it
since it has to be able to forward packets, requests and, potentially,
juggle multiple users.

I guess my point is that poorly written firmware in the router might
grab an IP address for the wireless port even if it is disabled.

John



--
\\\||///
------------------o000----(o)(o)----000o----------------
----------------------------()--------------------------
'' Madness takes its toll - Please have exact change. ''

John Dulak - Gnomeway Services - http://tinyurl.com/2qs6o6
 
Reply With Quote
 
bearclaw@cruller.invalid
Guest
Posts: n/a

 
      07-11-2007, 05:31 PM
In article <Z24li.1278$mS3.129@trnddc03>, John Dulak <(E-Mail Removed)>
wrote:

> I guess my point is that poorly written firmware in the router might
> grab an IP address for the wireless port even if it is disabled.


I think that is a very good point and also goes a long way toward
explaining why wireless connections can be so unreliable even after the
IP is issued. I haven't yet run across a case like you are talking
about, but I have seen stuff that I thought was just as weird.

It seems like a good idea to eliminate all other possible causes before
you go after the ones you can't directly do anything about, though. So I
still think the OP should follow BAU troubleshooting steps to identify
the IP interloper.

I wonder also if interference devices (like cordless phones, microwaves,
florescent lights, etc) could cause an 802.11b/g DHCP server to issue an
IP? While looking online for info on Apple's "Interference Robustness"
recently, I wound up reading a lot about the different ways in which the
802.11 standard deals with interference, and I don't recall that
particular issue being addressed. So, I don't know if it is even
possible.
 
Reply With Quote
 
 
 
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
"Unknown host" message with streaming audio jfbialek@usa.net Wireless Internet 1 09-30-2007 10:54 PM
Local DNS... "unknown host" Cyphos Linux Networking 6 12-26-2005 05:32 PM
DHCP Client list Broadband Hardware 4 05-11-2004 11:24 PM
eth0: Unknown host Nesquik Linux Networking 3 02-29-2004 02:36 PM
DHCP Client List? Jennifer Broadband Hardware 0 02-07-2004 03:08 PM