Gentoo Archives: gentoo-user

From: Mick <michaelkintzios@×××××.com>
To: gentoo-user@l.g.o
Subject: Re: [gentoo-user] Strange behaviour of dhcpcd
Date: Tue, 28 Oct 2014 16:29:00
In Reply to: [gentoo-user] Strange behaviour of dhcpcd by Marc Joliet
1 On Monday 27 Oct 2014 23:44:58 Marc Joliet wrote:
2 > Hi list
3 >
4 > First off: this is a "fixed" issue, in that I don't see the behaviour
5 > anymore, so time is not of the essence ;) . I'm only looking for an
6 > explanation, or for comments from other people who experienced this.
7 >
8 > So the issue was some really strange behaviour on the part of dhcpcd. I
9 > completed a move a few weeks ago and got an internet connection last
10 > Wednesday (using a local cable company, that is, using a cable modem
11 > connected to via ethernet). I reconfigured my system to use regular DHCP
12 > (a relief after the PPPoE mess in the dorm), but dhcpcd could not apply
13 > the default route; it *obtained* one, but failed with "if_addroute:
14 > Invalid argument". I tried it manually, to no effect: "ip route"
15 > complained about invalid arguments, and I think plain "route" said "file
16 > exists", but I'm not sure anymore (either way, the error messages were
17 > less than clear). The funny thing is, I *could* set the default route,
18 > just not to the one advertised via DHCP, but to the x.y.z.2+ instead of
19 > x.y.z.1, which even gave me access to the internet part of the time.
20 >
21 > Now the funny thing is what fixed it:
22 >
23 > *commenting out the entirety of /etc/dhcpcd.conf*
24 >
25 > Then dhcpcd ran with default settings and could apply the default route.
26 > Even more bizarre is the fact that it kept working after uncommenting it
27 > again (and I track it with git, so I'm 100% sure I got it back to its
28 > original state). This leads me to believe that there was some (corrupted?)
29 > persistent state somewhere that got overwritten by starting dhcpcd after I
30 > commented out the file, but I have no clue where.
31 >
32 > Has anyone seen this sort of behaviour before, or anything similar to it?
33 > I searched for the error messages I was seeing, but couldn't find
34 > anything. I was using gentoo-sources-3.15.9 (now I'm at 3.16.6) and
35 > dhcpcd 6.4.3 at the time, but also had the issue with dhcpcd 6.4.7, to
36 > which I could upgrade by using the aforementioned x.y.z.2 gateway. Perhaps
37 > it was a bug in the kernel? But that's just guessing.
38 >
39 > Regards,
41 Since dhcpcd doesn't misbehave any more it would be difficult to check what
42 was the cause of this problem. You didn't say if the cable modem is
43 functioning as a router or as in a full or half bridge mode and if there is a
44 router between your PC and the modem that distributes IP addresses. You also
45 didn't say if the ISP has allocated an IP block or just a single IP address.
47 I have had problems with dhcpcd over the years and in particular with it using
48 DUID, which my router does not like at all. Also, for some reason it first
49 checks for IPv6, then times out, and eventually it looks for IPv4 which takes
50 like forever, each time I connect to my wired network. In waiting for an IPv4
51 address it may set up APIPA and then sometime later will eventually look for
52 and obtain an IPv4 address from the router.
54 I have not found a solution to this annoying behaviour, however wirelessly the
55 IP address allocation is established immediately without delays. Go figure
56 ...
58 --
59 Regards,
60 Mick


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Subject Author
Re: [gentoo-user] Strange behaviour of dhcpcd Marc Joliet <marcec@×××.de>