[wellylug] What can cause a slow login?

[Jonathan Brewer]

Thanks to Pete Black re: checking /etc/hosts. I had a Debian box
exhibiting just such behaviour and found that I had not changed its
address there when I moved networks.

-----Original Message-----
From: wellylug-admin at lists.wellylug.org.nz
[mailto:wellylug-admin at lists.wellylug.org.nz] On Behalf Of
michael at diaspora.gen.nz
Sent: Tuesday, 23 November 2004 1:20 p.m.
To: wellylug at lists.wellylug.org.nz
Subject: Re: [wellylug] What can cause a slow login? 


Enkidu writes:
>If this had been a Windows box I'd have been deafened by yells of 
>"DNS", but what would make a Debian Linux box slow to login?
>
>Accessing using putty, the "login as:" comes up quickly, but the 
>password prompt doesn't arrive for 10s of seconds....

PAM & DNS.  I saw this sort of problem (ls also worked very quickly, but
ls -l didn't -- LDAP was also involved, looking up usernames) on a
Redhat box that was doing DNS lookups for ::1, the IPv6 address for
localhost, and getting 30 second timeouts from the DNS server it was
using.

If you do suspect DNS, login as root, use nohup and tcpdump to capture
all traffic on port 53; something like:

    nohup tcpdump -i eth0 -s 1500 -o /tmp/logfile port 53

logout, log back in again, and then use Ethereal to load up the logfile
and see if there is anything suspicious.
    -- michael.


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