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Groups > linux.debian.user > #178567 > unrolled thread

Why 2 dhclient processes running for eth0 (IPv4)?

Started byClark Wang <dearvoid@gmail.com>
First post2017-03-08 08:30 +0100
Last post2017-03-13 06:10 +0100
Articles 8 — 4 participants

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  Why 2 dhclient processes running for eth0 (IPv4)? Clark Wang <dearvoid@gmail.com> - 2017-03-08 08:30 +0100
    Re: Why 2 dhclient processes running for eth0 (IPv4)? Clark Wang <dearvoid@gmail.com> - 2017-03-10 12:00 +0100
      Re: Why 2 dhclient processes running for eth0 (IPv4)? <tomas@tuxteam.de> - 2017-03-10 12:40 +0100
        Re: Why 2 dhclient processes running for eth0 (IPv4)? <tomas@tuxteam.de> - 2017-03-10 14:40 +0100
        Re: Why 2 dhclient processes running for eth0 (IPv4)? Greg Wooledge <wooledg@eeg.ccf.org> - 2017-03-10 14:40 +0100
      Re: Why 2 dhclient processes running for eth0 (IPv4)? <tomas@tuxteam.de> - 2017-03-10 14:30 +0100
      Re: Why 2 dhclient processes running for eth0 (IPv4)? Jonathan Dowland <jmtd@debian.org> - 2017-03-10 14:30 +0100
    Re: Why 2 dhclient processes running for eth0 (IPv4)? Clark Wang <dearvoid@gmail.com> - 2017-03-13 06:10 +0100

#178567 — Why 2 dhclient processes running for eth0 (IPv4)?

FromClark Wang <dearvoid@gmail.com>
Date2017-03-08 08:30 +0100
SubjectWhy 2 dhclient processes running for eth0 (IPv4)?
Message-ID<tiEcN-38Q-13@gated-at.bofh.it>

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See following output from my system (Debian 8.6):

    root@debian:~# cat /etc/debian_version
    8.6
    root@debian:~# pgrep -af dhc
    506 dhclient -v -pf /run/dhclient.eth1.pid -lf
/var/lib/dhcp/dhclient.eth1.leases eth1
    447 dhclient -v -pf /run/dhclient.eth0.pid -lf
/var/lib/dhcp/dhclient.eth0.leases eth0
    601 dhclient -v -pf /run/dhclient.eth0.pid -lf
/var/lib/dhcp/dhclient.eth0.leases eth0
    664 dhclient -6 -pf /run/dhclient6.eth0.pid -lf
/var/lib/dhcp/dhclient6.eth0.leases eth0
    root@debian:~# grep -n -C3 eth0 /etc/network/interfaces
     7-auto lo
     8-iface lo inet loopback
     9-
    10:allow-hotplug eth0
    11:iface eth0 inet dhcp
    12:iface eth0 inet6 dhcp
    13-    accept_ra 1
    14-
    15-allow-hotplug eth1
    root@debian:~#

There are 2 `dhclient` processes running for `eth0` (IPv4). Rebooting does
not help for me.

Thanks.

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#178641

FromClark Wang <dearvoid@gmail.com>
Date2017-03-10 12:00 +0100
Message-ID<tjqr7-2Qu-3@gated-at.bofh.it>
In reply to#178567

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2017-03-08 15:24 GMT+08:00 Clark Wang <dearvoid@gmail.com>:

> See following output from my system (Debian 8.6):
>
>     root@debian:~# cat /etc/debian_version
>     8.6
>     root@debian:~# pgrep -af dhc
>     506 dhclient -v -pf /run/dhclient.eth1.pid -lf
> /var/lib/dhcp/dhclient.eth1.leases eth1
>     447 dhclient -v -pf /run/dhclient.eth0.pid -lf
> /var/lib/dhcp/dhclient.eth0.leases eth0
>     601 dhclient -v -pf /run/dhclient.eth0.pid -lf
> /var/lib/dhcp/dhclient.eth0.leases eth0
>     664 dhclient -6 -pf /run/dhclient6.eth0.pid -lf
> /var/lib/dhcp/dhclient6.eth0.leases eth0
>     root@debian:~# grep -n -C3 eth0 /etc/network/interfaces
>      7-auto lo
>      8-iface lo inet loopback
>      9-
>     10:allow-hotplug eth0
>     11:iface eth0 inet dhcp
>     12:iface eth0 inet6 dhcp
>     13-    accept_ra 1
>     14-
>     15-allow-hotplug eth1
>     root@debian:~#
>
> There are 2 `dhclient` processes running for `eth0` (IPv4). Rebooting does
> not help for me.
>

Anyone else has the same problem?

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#178642

From<tomas@tuxteam.de>
Date2017-03-10 12:40 +0100
Message-ID<tjr3Q-3kY-29@gated-at.bofh.it>
In reply to#178641
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On Fri, Mar 10, 2017 at 06:58:30PM +0800, Clark Wang wrote:

[...]

> Anyone else has the same problem?

No. At least not if I don't provoke it :-)

You could gather some hints by looking into /var/log/daemon.log (dhclient's
mumblings are there) and/or by having a look at /proc/<dhclient's PID>/fd.

Also, more "w" in the ps:

  ps wwwwauxf | less

then search for dhclient. wider command line, parent-child relationships as
additional hints.

Good luck
- -- tomás
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#178646

From<tomas@tuxteam.de>
Date2017-03-10 14:40 +0100
Message-ID<tjsW0-4FY-71@gated-at.bofh.it>
In reply to#178642
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On Fri, Mar 10, 2017 at 08:31:10AM -0500, Greg Wooledge wrote:
> On Fri, Mar 10, 2017 at 12:34:34PM +0100, tomas@tuxteam.de wrote:
> > Also, more "w" in the ps:
> > 
> >   ps wwwwauxf | less
> 
> >From ps(1):
> 
>        w      Wide output.  Use this option twice for unlimited width.
> 
> You never need more than two.

Habit acquired back then (really back then, you don't want to know :)

Old habits die hard. Thanks for the clarification.

- -- t
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#178647

FromGreg Wooledge <wooledg@eeg.ccf.org>
Date2017-03-10 14:40 +0100
Message-ID<tjsW0-4FY-73@gated-at.bofh.it>
In reply to#178642
On Fri, Mar 10, 2017 at 12:34:34PM +0100, tomas@tuxteam.de wrote:
> Also, more "w" in the ps:
> 
>   ps wwwwauxf | less

>From ps(1):

       w      Wide output.  Use this option twice for unlimited width.

You never need more than two.

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#178644

From<tomas@tuxteam.de>
Date2017-03-10 14:30 +0100
Message-ID<tjsMh-4Ar-11@gated-at.bofh.it>
In reply to#178641
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On Fri, Mar 10, 2017 at 01:23:36PM +0000, Jonathan Dowland wrote:
> On Fri, Mar 10, 2017 at 06:58:30PM +0800, Clark Wang wrote:
> > > There are 2 `dhclient` processes running for `eth0` (IPv4). Rebooting does
> > > not help for me.
> > >
> > 
> > Anyone else has the same problem?
> 
> I think I have sometimes seen this, but I do not know what provokes it. The most
> likely explanation is installing more than one network management system and/or
> leaving more than one configured. So for example I have had ifupdown and wicd both
> attempt to manage interfaces.
> 
> If you look at the parent PID for the dhclient instances, you might get some clues.
> (ps -eaf --forest for example, or pstree(1))

I was tempted to propose that too, but mine daemonizes and becomes
init's child (ifupdown, don't know what other network managers do).

Regards
- -- t
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#178645

FromJonathan Dowland <jmtd@debian.org>
Date2017-03-10 14:30 +0100
Message-ID<tjsMh-4Ar-13@gated-at.bofh.it>
In reply to#178641

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On Fri, Mar 10, 2017 at 06:58:30PM +0800, Clark Wang wrote:
> > There are 2 `dhclient` processes running for `eth0` (IPv4). Rebooting does
> > not help for me.
> >
> 
> Anyone else has the same problem?

I think I have sometimes seen this, but I do not know what provokes it. The most
likely explanation is installing more than one network management system and/or
leaving more than one configured. So for example I have had ifupdown and wicd both
attempt to manage interfaces.

If you look at the parent PID for the dhclient instances, you might get some clues.
(ps -eaf --forest for example, or pstree(1))


-- 
Jonathan Dowland
Please do not CC me, I am subscribed to the list.

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#178742

FromClark Wang <dearvoid@gmail.com>
Date2017-03-13 06:10 +0100
Message-ID<tkqp4-3Rm-9@gated-at.bofh.it>
In reply to#178567

[Multipart message — attachments visible in raw view] — view raw

2017-03-08 15:24 GMT+08:00 Clark Wang <dearvoid@gmail.com>:

> See following output from my system (Debian 8.6):
>
>     root@debian:~# cat /etc/debian_version
>     8.6
>     root@debian:~# pgrep -af dhc
>     506 dhclient -v -pf /run/dhclient.eth1.pid -lf
> /var/lib/dhcp/dhclient.eth1.leases eth1
>     447 dhclient -v -pf /run/dhclient.eth0.pid -lf
> /var/lib/dhcp/dhclient.eth0.leases eth0
>     601 dhclient -v -pf /run/dhclient.eth0.pid -lf
> /var/lib/dhcp/dhclient.eth0.leases eth0
>     664 dhclient -6 -pf /run/dhclient6.eth0.pid -lf
> /var/lib/dhcp/dhclient6.eth0.leases eth0
>     root@debian:~# grep -n -C3 eth0 /etc/network/interfaces
>      7-auto lo
>      8-iface lo inet loopback
>      9-
>     10:allow-hotplug eth0
>     11:iface eth0 inet dhcp
>     12:iface eth0 inet6 dhcp
>     13-    accept_ra 1
>     14-
>     15-allow-hotplug eth1
>     root@debian:~#
>
> There are 2 `dhclient` processes running for `eth0` (IPv4). Rebooting does
> not help for me.
>

Thanks all for pointing me to the debug direction.

I moved /sbin/dhclient to /sbin/dhclient.bin and rewrite /sbin/dhclient as
a shell script which would call /sbin/dhclient.bin and prints some proc
hierarchy info. It turned out both /etc/init.d/networking and systemd would
call ifup. See following example (only for IPv4):

==== Sun Mar 12 21:38:08 PDT 2017 ====
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root       433  0.0  1.1  20052  2880 ?        S    21:38   0:00 /bin/bash
/sbin/dhclient -v -pf /run/dhclient.eth0.pid -lf
/var/lib/dhcp/dhclient.eth0.leases eth0
systemd(1)-+-networking(285)---ifup(427)---sh(432)---dhclient(433)---pstree(441)
           |-systemd-journal(160)
           `-systemd-udevd(164)-+-systemd-udevd(167)
                                |-systemd-udevd(171)
                                |-systemd-udevd(172)
                                |-systemd-udevd(173)
                                |-systemd-udevd(174)
                                |-systemd-udevd(175)
                                |-systemd-udevd(176)
                                |-systemd-udevd(177)
                                |-systemd-udevd(178)
                                `-systemd-udevd(179)

==== Sun Mar 12 21:38:10 PDT 2017 ====
USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
root       518  0.0  1.1  20052  2920 ?        S    21:38   0:00 /bin/bash
/sbin/dhclient -v -pf /run/dhclient.eth0.pid -lf
/var/lib/dhcp/dhclient.eth0.leases eth0
systemd(1)-+-dhclient.bin(457)
           |-ifup(509)---sh(517)---dhclient(518)---pstree(522)
           |-nfs-common(512)---nfs-common(523)
           |-systemd-journal(160)
           `-systemd-udevd(164)-+-systemd-udevd(167)
                                |-systemd-udevd(171)
                                |-systemd-udevd(172)
                                |-systemd-udevd(173)
                                |-systemd-udevd(174)
                                |-systemd-udevd(175)
                                |-systemd-udevd(176)
                                |-systemd-udevd(177)
                                |-systemd-udevd(178)
                                `-systemd-udevd(179)

I know nothing about systemd so I disabled the "networking" service with
"sysv-rc-conf" but then network would not be up after reboot. So how can I
make sure only "systemd" or the "networking" service would bring network up?

-clark

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