Gentoo Archives: gentoo-user

From: daid kahl <daidxor@×××××.com>
To: gentoo-user@l.g.o
Subject: DNS Issues [Was: [gentoo-user] Re: Slow Login, Sudo, etc.]
Date: Wed, 13 Oct 2010 13:51:30
1 On 13 October 2010 22:38, daid kahl <daidxor@×××××.com> wrote:
2 >> On 10/11/2010 11:38 PM, daid kahl wrote:
3 >>
4 >>> However, I noticed that logins, su, and sudo are all responding
5 >>> slowly.  This was all fixed and fine once I updated my configuration
6 >>> files, but this week it's acting up again.  Before it was just su and
7 >>> sudo that I noticed as slow (authentication takes around 20 seconds).
8 >>> But now even logins are delayed (xdm or command line).
9 >
10 > On 13 October 2010 07:12, walt <w41ter@×××××.com> wrote:
11 >>
12 >> Whenever I see something that eventually works, but only after a long
13 >> delay, I think of DNS problems.
14 >>
15 >> Who might be doing a nonsensical DNS lookup, I have no idea.  But you
16 >> might consider running a packet sniffer (wireshark, etc) while logging
17 >> in or doing an su.  Are you running your own local name server?
18 >
19 > Very very intersting!!
20 >
21 > The main correlation I've seen so far is with dhcpcd.  Sometimes at my
22 > work I get a 192. IP (which doesn't work), and other times I get a
23 > 133. IP (which is correct).  In fact, sometimes dhcp is giving me an
24 > IP address and resolv.conf related to a university I was visiting like
25 > a month ago.
26 >
27 > In other words, I know I have some networking problems, but I was
28 > reluctant to imagine it was at all related to this login problem, even
29 > though I had some basic empirical data on it.
30 >
31 > Anyway, it happened again tonight, and it was resolved after I did
32 > some of the same emerges as before, but I think that might be just
33 > chance.
34 >
35 > I look into the DNS stuff.  Thanks for the sanity check!
36 >
37 > ~daid
38 >
39 > PS: Sorry for the initial top posting on myself...
40 >
42 I've been having some networking problems lately, and apparently it's
43 mucking up my logins and things like sudo sometimes as well. Thanks
44 to Walt for telling me these two problems might be related.
46 I'm on a MacBook, and I wouldn't say this is the first time I've had
47 networking issues, but the hardware may not be at all the problem.
49 At home I use wireless and NetworkManager for that. This is because
50 I've never managed to get wicd working correctly for my wireless.
51 Just tonight I had to stop dhcpcd for NM to actually connect. Maybe
52 this is normal, I kind of forget how I hack things sometimes, though.
54 At work I'm using DHCP, and the nameserver is controlled by the
55 network. In that case, if I reboot, I (sometimes) get a correct IP.
56 Normally I'm on top of what's controlling what, but I'm more confused
57 these days. I can't tell if it's done by net, or dhcpd or what, since
58 restarting them doesn't usually reboot net.eth0. Sometimes I get wicd
59 working on it. It's kind of a mess!
61 Very curiously, as in my previous post I mentioned, sometimes I'm
62 getting resolv.conf for a university I visited like last month. Why
63 or how that would happen I don't know. It's some config problem? I
64 need to dig through everything, since sometimes at the university I
65 statically connect, but I'm pretty sure all those are commented out.
66 Why it will assign me up to three different nameservers, seemingly
67 randomly, for ethernet, I can't understand.
69 So, firstly I'll need some troubleshooting. I already have wireshark
70 installed, so that could be helpful.
72 I guess what might be helpful right now is how to purge my networking
73 stuff and just start it all from scratch. There is so much garbage
74 installed right now so I can hack it together that it's just a mess
75 (this happened because I can get it to function eventually, yuck).
77 Cheers,
78 daid


Subject Author
Re: DNS Issues [Was: [gentoo-user] Re: Slow Login, Sudo, etc.] Alan McKinnon <alan.mckinnon@×××××.com>