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Groups > linux.kernel > #1701458 > unrolled thread

sysctl, argument parsing, possible bug

Started byMassimo Sala <massimo.sala.71@gmail.com>
First post2017-08-01 22:50 +0200
Last post2017-08-02 04:50 +0200
Articles 6 — 4 participants

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  sysctl, argument parsing, possible bug Massimo Sala <massimo.sala.71@gmail.com> - 2017-08-01 22:50 +0200
    Re: sysctl, argument parsing, possible bug Cong Wang <xiyou.wangcong@gmail.com> - 2017-08-01 23:30 +0200
      Re: sysctl, argument parsing, possible bug Massimo Sala <massimo.sala.71@gmail.com> - 2017-08-01 23:40 +0200
        Re: sysctl, argument parsing, possible bug Cong Wang <xiyou.wangcong@gmail.com> - 2017-08-02 00:00 +0200
          Re: sysctl, argument parsing, possible bug "Luis R. Rodriguez" <mcgrof@kernel.org> - 2017-08-03 00:00 +0200
      Re: sysctl, argument parsing, possible bug Stephen Hemminger <stephen@networkplumber.org> - 2017-08-02 04:50 +0200

#1701458 — sysctl, argument parsing, possible bug

FromMassimo Sala <massimo.sala.71@gmail.com>
Date2017-08-01 22:50 +0200
Subjectsysctl, argument parsing, possible bug
Message-ID<u9Mh4-jv-15@gated-at.bofh.it>
cat /proc/sys/net/ipv4/conf/eth0.100/forwarding

0

sysctl net.ipv4.conf.eth0.100.forwarding
error: "net.ipv4.conf.eth0.100.forwarding" is an unknown key

uname -a
Linux ip-172-31-45-203 4.9.38-16.33.amzn1.x86_64 #1 SMP Thu Jul 20
01:31:29 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux

cat /etc/issue
Amazon Linux AMI release 2017.03


best regards, Sala

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#1701516

FromCong Wang <xiyou.wangcong@gmail.com>
Date2017-08-01 23:30 +0200
Message-ID<u9MTL-Oh-7@gated-at.bofh.it>
In reply to#1701458
On Tue, Aug 1, 2017 at 1:47 PM, Massimo Sala <massimo.sala.71@gmail.com> wrote:
> cat /proc/sys/net/ipv4/conf/eth0.100/forwarding
> 0
>
> sysctl net.ipv4.conf.eth0.100.forwarding
> error: "net.ipv4.conf.eth0.100.forwarding" is an unknown key
>

Use echo instead, sysctl doesn't understand eth0.100
is a netdev name, sigh.

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#1701519

FromMassimo Sala <massimo.sala.71@gmail.com>
Date2017-08-01 23:40 +0200
Message-ID<u9N3r-Rr-1@gated-at.bofh.it>
In reply to#1701516
Do you confirm it is a sysctl parsing bug ?

Bosybox handles these cases, so I think also standalone sysctl have to.

Or at least someone must update sysctl docs / MAN about this.

Best regards, Sala


On 01/08/2017, Cong Wang <xiyou.wangcong@gmail.com> wrote:
> On Tue, Aug 1, 2017 at 1:47 PM, Massimo Sala <massimo.sala.71@gmail.com>
> wrote:
>> cat /proc/sys/net/ipv4/conf/eth0.100/forwarding
>> 0
>>
>> sysctl net.ipv4.conf.eth0.100.forwarding
>> error: "net.ipv4.conf.eth0.100.forwarding" is an unknown key
>>
>
> Use echo instead, sysctl doesn't understand eth0.100
> is a netdev name, sigh.
>

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#1701534

FromCong Wang <xiyou.wangcong@gmail.com>
Date2017-08-02 00:00 +0200
Message-ID<u9NmN-ZP-3@gated-at.bofh.it>
In reply to#1701519
On Tue, Aug 1, 2017 at 2:34 PM, Massimo Sala <massimo.sala.71@gmail.com> wrote:
> Do you confirm it is a sysctl parsing bug ?
>
> Bosybox handles these cases, so I think also standalone sysctl have to.
>
> Or at least someone must update sysctl docs / MAN about this.
>

Maybe, sysctl seems (I never look into it) just to interpret dot as
a separator, unless it reads from the /proc/sys/ directory, it can
not know eth0.100 is actually a netdev name.

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#1702523

From"Luis R. Rodriguez" <mcgrof@kernel.org>
Date2017-08-03 00:00 +0200
Message-ID<ua9Qm-7en-23@gated-at.bofh.it>
In reply to#1701534
On Tue, Aug 01, 2017 at 02:54:51PM -0700, Cong Wang wrote:
> On Tue, Aug 1, 2017 at 2:34 PM, Massimo Sala <massimo.sala.71@gmail.com> wrote:
> > Do you confirm it is a sysctl parsing bug ?
> >
> > Bosybox handles these cases, so I think also standalone sysctl have to.
> >
> > Or at least someone must update sysctl docs / MAN about this.
> >
> 
> Maybe, sysctl seems (I never look into it) just to interpret dot as
> a separator, unless it reads from the /proc/sys/ directory, it can
> not know eth0.100 is actually a netdev name.

Using echo or sysctl -w works for me, try upgrading your procps,
I have procps-3.3.12. Busybox sysctl fails though, so it would
seems this is an issue with busybox, go fix that.

With procps-3.3.12.:

Setting:

ergon:~ # cat /proc/sys/net/ipv4/conf/eth0.100/forwarding 
1

ergon:~ # sysctl -w net.ipv4.conf.eth0/100.forwarding=0
net.ipv4.conf.eth0/100.forwarding = 0

ergon:~ # cat /proc/sys/net/ipv4/conf/eth0.100/forwarding 

0

Querying:

ergon:~ # sysctl net.ipv4.conf.eth0/100.forwarding
net.ipv4.conf.eth0/100.forwarding = 0

With busybox:

ergon:~ # busybox-static sysctl net.ipv4.conf.eth0/100.forwarding
sysctl: error: 'net.ipv4.conf.eth0.100.forwarding' is an unknown key

  Luis

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#1701642

FromStephen Hemminger <stephen@networkplumber.org>
Date2017-08-02 04:50 +0200
Message-ID<u9RTr-3Xy-1@gated-at.bofh.it>
In reply to#1701516
On Tue, 1 Aug 2017 14:27:37 -0700
Cong Wang <xiyou.wangcong@gmail.com> wrote:

> On Tue, Aug 1, 2017 at 1:47 PM, Massimo Sala <massimo.sala.71@gmail.com> wrote:
> > cat /proc/sys/net/ipv4/conf/eth0.100/forwarding
> > 0
> >
> > sysctl net.ipv4.conf.eth0.100.forwarding
> > error: "net.ipv4.conf.eth0.100.forwarding" is an unknown key
> >  
> 
> Use echo instead, sysctl doesn't understand eth0.100
> is a netdev name, sigh.

sysctl happily accepts / as a separator see man sysctl(8)

PARAMETERS
       variable
              The  name  of  a  key to read from.  An example is kernel.ostype.  The '/' separator is also
              accepted in place of a '.'.

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