[gentoo-user] Net / dhcp (miss)behaviour

[gentoo-user] Net / dhcp (miss)behaviour

[Marko Kocić]

I'm running gentoo on my dual boot windows laptop.

I use dhcp to connect to the the internet through cable modem.
Sometimes (in the evenings) it just fails to automatically obtain IP
address from dhcp server (timeouts).
I tried different settings in /etc/conf.d/net file (timeout and
different dhcpc options) and switching between dhclient and dhcpd, but
with no luck.

When I reboot to windows it just works. I contacted my ISP, but they
said they don't give support for Linux.

Is there a way to configure dhcp/dhclient to behave exactly like DHCP
in Windows XP?

Regards,
Marko
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Alan McKinnon]

On Friday 18 January 2008, Marko Kocić wrote:
> I'm running gentoo on my dual boot windows laptop.
>
> I use dhcp to connect to the the internet through cable modem.
> Sometimes (in the evenings) it just fails to automatically obtain IP
> address from dhcp server (timeouts).
> I tried different settings in /etc/conf.d/net file (timeout and
> different dhcpc options) and switching between dhclient and dhcpd,
> but with no luck.
>
> When I reboot to windows it just works. I contacted my ISP, but they
> said they don't give support for Linux.
>
> Is there a way to configure dhcp/dhclient to behave exactly like DHCP
> in Windows XP?

Where is the dhcp server? On the cable provider's network, or on the 
modem itself?

I have found that dhcp can do weird stuff sometimes and Windows client 
don't always follow the standard method. Then again, what else is new?

My first diagnostic step would be to get another machine on the network 
and sniff dhcp traffic when using Windows and Gentoo to see what the 
difference is.

alan


-- 
Alan McKinnon
alan dot mckinnon at gmail dot com
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Marko Kocić]

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On Jan 18, 2008 6:50 PM, Alan McKinnon <alan.mckinnon@gmail.com> wrote:
>
> On Friday 18 January 2008, Marko Kocić wrote:
> > I'm running gentoo on my dual boot windows laptop.
> >
> > I use dhcp to connect to the the internet through cable modem.
> > Sometimes (in the evenings) it just fails to automatically obtain IP
> > address from dhcp server (timeouts).
> > I tried different settings in /etc/conf.d/net file (timeout and
> > different dhcpc options) and switching between dhclient and dhcpd,
> > but with no luck.
> >
> > When I reboot to windows it just works. I contacted my ISP, but they
> > said they don't give support for Linux.
> >
> > Is there a way to configure dhcp/dhclient to behave exactly like DHCP
> > in Windows XP?
>
> Where is the dhcp server? On the cable provider's network, or on the
> modem itself?

On cable providers network.

> I have found that dhcp can do weird stuff sometimes and Windows client
> don't always follow the standard method. Then again, what else is new?

> My first diagnostic step would be to get another machine on the network
> and sniff dhcp traffic when using Windows and Gentoo to see what the
> difference is.

I can't do that, cause I don't have switch/hub, just a cable modem directly
conencted to laptop.

I was looking for some magic "enable windows emulation mode" for dhcp.

> alan
>

Thanks,
Marko
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Marko Kocić]

> I never used cable modem and don't know how it connects to the PC, so I
> might be saying something completely wrong here,

Regular network cable going directly from cable modem to laptop.

> but can't you sniff the
> traffic directly from the laptop by capturing packets on the interface
> connected to the cable modem?

I can do that when interface is up is up and running.
But it is /etc/init.d/net.eth0 that is failing because of dhcp error.

What should I use? Ethereal? What should I look for?
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Etaoin Shrdlu]

On Friday 18 January 2008, Marko Kocić wrote:

> > My first diagnostic step would be to get another machine on the
> > network and sniff dhcp traffic when using Windows and Gentoo to see
> > what the difference is.
>
> I can't do that, cause I don't have switch/hub, just a cable modem
> directly conencted to laptop.

I never used cable modem and don't know how it connects to the PC, so I 
might be saying something completely wrong here, but can't you sniff the 
traffic directly from the laptop by capturing packets on the interface 
connected to the cable modem?
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Kevin]

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On Jan 18, 2008 12:17 PM, Marko Kocić <marko.kocic@gmail.com> wrote:

> > I never used cable modem and don't know how it connects to the PC, so I
> > might be saying something completely wrong here,
>
> Regular network cable going directly from cable modem to laptop.
>
> > but can't you sniff the
> > traffic directly from the laptop by capturing packets on the interface
> > connected to the cable modem?
>
> I can do that when interface is up is up and running.
> But it is /etc/init.d/net.eth0 that is failing because of dhcp error.
>
> What should I use? Ethereal? What should I look for?
> --
> gentoo-user@lists.gentoo.org mailing list
>
>

You can try Ethereal (which now goes by wireshark).   Question,  when it
fails have you logged in and done a /etc/init.d/net stop / start?    Just
curious if it will "force" itself up.

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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Marko Kocić]

> Actually, as long as the interface is up, you can sniff traffic even if
> it does not have an IP address. Emerge wireshark (somehow...), do (as
> root) an "ip link set eth0 up" (or "ifconfig eth0 up") and run
> wireshark. Start capturing packets, run dhcpcd from the command line (or
> whatever DHCP client you use), and see what goes on the wire. You should
> see DHCP discovery/offer/request messages, or maybe not all of them if
> things are not working correctly. For each DHCP packet, look at the DHCP
> payload details from wireshark (you can save the capture for later
> viewing too).
>
> Then, start windows, install wireshark for windows, and do the same. To
> force a DHCP negotiation in windows, open a command prompt and issue
> an "ipconfig /release" followed by an "ipconfig /renew" (IIRC). Look at
> the traffic captured after the /renew command, and look for obvious or
> blatant differences between windows and linux in DHCP packets of the
> same kind.

Thanks for the info. I'll try that.

Also, I just found by googling that there is dhcp client called
net-misc/pump which
have --win-client-ident option. I'll try that too.

Regards,
Marko
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Etaoin Shrdlu]

On Friday 18 January 2008, Marko Kocić wrote:

> > I never used cable modem and don't know how it connects to the PC,
> > so I might be saying something completely wrong here,
>
> Regular network cable going directly from cable modem to laptop.
>
> > but can't you sniff the
> > traffic directly from the laptop by capturing packets on the
> > interface connected to the cable modem?
>
> I can do that when interface is up is up and running.
> But it is /etc/init.d/net.eth0 that is failing because of dhcp error.
>
> What should I use? Ethereal? What should I look for?

Actually, as long as the interface is up, you can sniff traffic even if 
it does not have an IP address. Emerge wireshark (somehow...), do (as 
root) an "ip link set eth0 up" (or "ifconfig eth0 up") and run 
wireshark. Start capturing packets, run dhcpcd from the command line (or 
whatever DHCP client you use), and see what goes on the wire. You should 
see DHCP discovery/offer/request messages, or maybe not all of them if 
things are not working correctly. For each DHCP packet, look at the DHCP 
payload details from wireshark (you can save the capture for later 
viewing too).

Then, start windows, install wireshark for windows, and do the same. To 
force a DHCP negotiation in windows, open a command prompt and issue 
an "ipconfig /release" followed by an "ipconfig /renew" (IIRC). Look at 
the traffic captured after the /renew command, and look for obvious or 
blatant differences between windows and linux in DHCP packets of the 
same kind.
--
gentoo-user@lists.gentoo.org mailing list

Re: [gentoo-user] Net / dhcp (miss)behaviour

[Mick]

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On Friday 18 January 2008, Marko Kocić wrote:
> > Actually, as long as the interface is up, you can sniff traffic even if
> > it does not have an IP address. Emerge wireshark (somehow...), do (as
> > root) an "ip link set eth0 up" (or "ifconfig eth0 up") and run
> > wireshark. Start capturing packets, run dhcpcd from the command line (or
> > whatever DHCP client you use), and see what goes on the wire. You should
> > see DHCP discovery/offer/request messages, or maybe not all of them if
> > things are not working correctly. For each DHCP packet, look at the DHCP
> > payload details from wireshark (you can save the capture for later
> > viewing too).
> >
> > Then, start windows, install wireshark for windows, and do the same. To
> > force a DHCP negotiation in windows, open a command prompt and issue
> > an "ipconfig /release" followed by an "ipconfig /renew" (IIRC). Look at
> > the traffic captured after the /renew command, and look for obvious or
> > blatant differences between windows and linux in DHCP packets of the
> > same kind.
>
> Thanks for the info. I'll try that.
>
> Also, I just found by googling that there is dhcp client called
> net-misc/pump which
> have --win-client-ident option. I'll try that too.

I wonder if my similar problem is related to what you report here:  I am using 
dhcpcd and ifplug with my ADSL router, which acts as the dhcp server on my 
LAN.  For some reason ifplug does not always manage to get an IP address from 
the router and I end up with an APIPA address.  /etc/init.d/net.eth0 
stop/start gets it going again.  This problem only occurs if I disconnect and 
then reconnect the ethernet cable.  No such problem exists when I boot the 
machine with the cable already connected to the NIC.  I haven't changed 
timeouts or anything else from the dhcpcd defaults.  I have always attributed 
this problem to a somewhat slow dhcp server on the router.

As a note:  WinXP machines do not have any such problem.  Even though they may 
end up with a APIPA address, they will in minute or so drop it and acquire a 
10.10.10.XXX domain address from the router.  dhcpcpd does not seem to have 
this flexibility.
-- 
Regards,
Mick

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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Marko Kocić]

> I wonder if my similar problem is related to what you report here:  I am using
> dhcpcd and ifplug with my ADSL router, which acts as the dhcp server on my
> LAN.  For some reason ifplug does not always manage to get an IP address from
> the router and I end up with an APIPA address.  /etc/init.d/net.eth0
> stop/start gets it going again.  This problem only occurs if I disconnect and
> then reconnect the ethernet cable.  No such problem exists when I boot the
> machine with the cable already connected to the NIC.  I haven't changed
> timeouts or anything else from the dhcpcd defaults.  I have always attributed
> this problem to a somewhat slow dhcp server on the router.

It is similar, with a difference that /etc/init.d/net.eth0 restart
doesn't help. I tried
enlarging timeout but with no help.

>
> As a note:  WinXP machines do not have any such problem.  Even though they may
> end up with a APIPA address, they will in minute or so drop it and acquire a
> 10.10.10.XXX domain address from the router.  dhcpcpd does not seem to have
> this flexibility.

I noticed that in most cases after I boot to windows, when I reboot
back to linux I can't connect.
When I reboot back to windows, net is up.

When it fails I noticed that it send DHCP requests, but doesn't get a response.

I tried dhclient, dhcpd and pump, and the results are allways the
same. It happens in the evenings, when internet traffic is high.
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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Roy Wright]

Marko Kocić wrote:
> I noticed that in most cases after I boot to windows, when I reboot
> back to linux I can't connect.
> When I reboot back to windows, net is up.
>
> When it fails I noticed that it send DHCP requests, but doesn't get a response.
>
> I tried dhclient, dhcpd and pump, and the results are allways the
> same. It happens in the evenings, when internet traffic is high.
>   
Try "ipconnect /release" before rebooting to linux.

Also I had a similar problem when I accidentally had two dhcp servers
running in my home lan.  A hair pulling two days.  :-)

I'd also suggest picking up a cheap non-wireless router (ex: linksys
BEFSR41). 
This will help isolate your box from being dependent on your ISP's dhcp
server.


HTH,
Roy


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Re: [gentoo-user] Net / dhcp (miss)behaviour

[Tony Davison]

On Saturday 19 January 2008 22:09:50 Marko Kocić wrote:
> > I wonder if my similar problem is related to what you report here:  I am
> > using dhcpcd and ifplug with my ADSL router, which acts as the dhcp
> > server on my LAN.  For some reason ifplug does not always manage to get
> > an IP address from the router and I end up with an APIPA address. 
> > /etc/init.d/net.eth0 stop/start gets it going again.  This problem only
> > occurs if I disconnect and then reconnect the ethernet cable.  No such
> > problem exists when I boot the machine with the cable already connected
> > to the NIC.  I haven't changed timeouts or anything else from the dhcpcd
> > defaults.  I have always attributed this problem to a somewhat slow dhcp
> > server on the router.
>
> It is similar, with a difference that /etc/init.d/net.eth0 restart
> doesn't help. I tried
> enlarging timeout but with no help.
>
> > As a note:  WinXP machines do not have any such problem.  Even though
> > they may end up with a APIPA address, they will in minute or so drop it
> > and acquire a 10.10.10.XXX domain address from the router.  dhcpcpd does
> > not seem to have this flexibility.
>
> I noticed that in most cases after I boot to windows, when I reboot
> back to linux I can't connect.
> When I reboot back to windows, net is up.
>
> When it fails I noticed that it send DHCP requests, but doesn't get a
> response.
>
> I tried dhclient, dhcpd and pump, and the results are allways the
> same. It happens in the evenings, when internet traffic is high.

Windows is not releasing the lease correctly, so the CM ignores request from 
the same MAC address for a new leasr, workround is to reboot the cm whem you 
reboot to gentoo.

This works in the UK YMMV elsewhere.

--
Tony Davison
--
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[gentoo-user] Re: Net / dhcp (miss)behaviour

[Marko Kocić]

It seems like that is the problem. Ipconfig /release or disabling net
conn in win before reboot doesnt help. Rebooting modem smtimes helps
but mostly not. Is it posible to somehow configure dhcp client to use
lease from windows?

On 1/20/08, Tony Davison <tony.davison2@ntlworld.com> wrote:
> On Saturday 19 January 2008 22:09:50 Marko Kocić wrote:
> > > I wonder if my similar problem is related to what you report here:  I am
> > > using dhcpcd and ifplug with my ADSL router, which acts as the dhcp
> > > server on my LAN.  For some reason ifplug does not always manage to get
> > > an IP address from the router and I end up with an APIPA address.
> > > /etc/init.d/net.eth0 stop/start gets it going again.  This problem only
> > > occurs if I disconnect and then reconnect the ethernet cable.  No such
> > > problem exists when I boot the machine with the cable already connected
> > > to the NIC.  I haven't changed timeouts or anything else from the dhcpcd
> > > defaults.  I have always attributed this problem to a somewhat slow dhcp
> > > server on the router.
> >
> > It is similar, with a difference that /etc/init.d/net.eth0 restart
> > doesn't help. I tried
> > enlarging timeout but with no help.
> >
> > > As a note:  WinXP machines do not have any such problem.  Even though
> > > they may end up with a APIPA address, they will in minute or so drop it
> > > and acquire a 10.10.10.XXX domain address from the router.  dhcpcpd does
> > > not seem to have this flexibility.
> >
> > I noticed that in most cases after I boot to windows, when I reboot
> > back to linux I can't connect.
> > When I reboot back to windows, net is up.
> >
> > When it fails I noticed that it send DHCP requests, but doesn't get a
> > response.
> >
> > I tried dhclient, dhcpd and pump, and the results are allways the
> > same. It happens in the evenings, when internet traffic is high.
>
> Windows is not releasing the lease correctly, so the CM ignores request from
> the same MAC address for a new leasr, workround is to reboot the cm whem you
> reboot to gentoo.
>
> This works in the UK YMMV elsewhere.
>
> --
> Tony Davison
> --
> gentoo-user@lists.gentoo.org mailing list
>
>

Re: [gentoo-user] Re: Net / dhcp (miss)behaviour

[Alan McKinnon]

On Sunday 20 January 2008, Marko Kocić wrote:
> 2008-01-20 16:07
>    
> It seems like that is the problem. Ipconfig /release or disabling net
> conn in win before reboot doesnt help. Rebooting modem smtimes helps
> but mostly not. Is it posible to somehow configure dhcp client to use
> lease from windows?

Does pump with the -R option work correctly?

-- 
Alan McKinnon
alan dot mckinnon at gmail dot com
--
gentoo-user@lists.gentoo.org mailing list

[gentoo-user] Re: Net / dhcp (miss)behaviour

[Marko Kocić]

No. Whatever I do with pump I get "Operation failed".

On 1/20/08, Alan McKinnon <alan.mckinnon@gmail.com> wrote:
> On Sunday 20 January 2008, Marko Kocić wrote:
> > 2008-01-20 16:07
> >
> > It seems like that is the problem. Ipconfig /release or disabling net
> > conn in win before reboot doesnt help. Rebooting modem smtimes helps
> > but mostly not. Is it posible to somehow configure dhcp client to use
> > lease from windows?
>
> Does pump with the -R option work correctly?
>
> --
> Alan McKinnon
> alan dot mckinnon at gmail dot com
> --
> gentoo-user@lists.gentoo.org mailing list
>
>