Bug 1275389

Summary: how does dhclient's "-n" option work ?
Product: [Fedora] Fedora Reporter: Pavel Šimerda (pavlix) <psimerda>
Component: dhcpAssignee: Jiri Popelka <jpopelka>
Status: CLOSED EOL QA Contact: Fedora Extras Quality Assurance <extras-qa>
Severity: unspecified Docs Contact:
Priority: unspecified    
Version: 23CC: jpopelka, thozza
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Last Closed: 2016-12-20 15:10:20 UTC Type: Bug
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Description Pavel Šimerda (pavlix) 2015-10-26 18:31:40 UTC
Description of problem:

Manual page describes the `-n` option to suppress system configuration changes. It is useful for debugging networks and especially DHCP servers. But the actual binary doesn't seem to know that option.


Version-Release number of selected component (if applicable):

dhcp-client-4.3.3-1.fc23.x86_64


How reproducible:

100%


Steps to Reproduce:
1. dhclient -n eth0


Actual results:

Usage is printed.


Expected results:

dhclient should be started.


Additional info:

dhclient should avoid touching any system configuration.

Comment 1 Jiri Popelka 2015-10-26 18:46:45 UTC
See bug #1133941, comment #3

Maybe the man page should explicitly say not to specify any interface when using this option ?

Comment 2 Pavel Šimerda (pavlix) 2015-10-27 13:06:58 UTC
1) I don't understand how to use the `-n` option properly then. I do want to start dhclient on a specific interface but I don't want it to do any changes to the system configuration. Maybe I misunderstood the meaning of the option, I was looking for something like "dhcpcd -T".

2) "dhclient -d -S -n" without any interface also doesn't work.

I'm afraid the manpage doesn't describe the option correctly.

Comment 3 Jiri Popelka 2015-10-30 18:55:09 UTC
(In reply to Pavel Šimerda (pavlix) from comment #2)
> 1) I don't understand how to use the `-n` option properly then. I do want to
> start dhclient on a specific interface but I don't want it to do any changes
> to the system configuration. Maybe I misunderstood the meaning of the
> option, I was looking for something like "dhcpcd -T".

So I checked the code and did some searching (found only [1]),
but can't really see what's the '-n' use-case.
It however doesn't look like to work similarly to "dhcpcd -T".

[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=430538

> 2) "dhclient -d -S -n" without any interface also doesn't work.

Yes, seems they can't be used together as "-S" implies an interface to be specified, while "-n" implies no interface.

> I'm afraid the manpage doesn't describe the option correctly.

Well, it says 'Do not configure any interfaces.' and I understand it as 'do nothing' and that's what it seems to be doing :-)
The questing for me is what's the use-case.

Comment 4 Pavel Šimerda (pavlix) 2015-10-30 19:59:57 UTC
(In reply to Jiri Popelka from comment #3)
> Well, it says 'Do not configure any interfaces.' and I understand it as 'do
> nothing' and that's what it seems to be doing :-)
> The questing for me is what's the use-case.

I don't see a use case either.

Comment 5 Fedora End Of Life 2016-11-24 12:55:47 UTC
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