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Slow sudo on Ubuntu

Excessive delay after typing sudo?

Looks as though the optional pam_ck_connector.so is hanging not only sudo but other auth processes (eg roundcube/dovecot/imap).

From here by erikdhansen (http://ubuntuforums.org/member.php?u=36598)

http://ubuntuforums.org/showpost.php?p=10399729&postcount=4

(Copied in case ubuntu reorganise their forums!)

"Re: SSH Login takes long time (no DNS Problem)
So I was having this same problem and it wasn't the DNS issue that everyone points to. It ended up being a problem with PAM.

imap on *hostname* status: failed

We noticed this appearing in one of the mailserver logs. Not often, perhaps once a week.

imap failed @ *TIMESTAMP*. A restart was attempted automagically.

Service Check Method: [socket connect]

Reason: TCP Transaction Log:
<< * OK [CAPABILITY IMAP4rev1 UIDPLUS CHILDREN NAMESPACE THREAD=ORDEREDSUBJECT THREAD=REFERENCES SORT QUOTA IDLE ACL ACL2=UNION STARTTLS] Courier-IMAP ready. Copyright 1998-2011 Double Precision, Inc. See COPYING for distribution information.
>> A001 LOGIN __cpanel__service__auth__imap__*********
<< * BYE Temporary problem, please try again later

SSH dropped connections workaround (eg on Virgin Media) - write failed, broken pipe etc on Linux

A quick workaround for dropping connections and broken pipe errors.

very annoying as many X based terminal apps freeze up at this point.

Adding

ServerAliveInterval 120

to ssh_config

helps avoid this - even on the Virgin Media cable connection and the allegedly "super"hub.

(I've seen people recommend turning hub off and on and all sorts of chicken waving - including switching to Bridge Mode - which is a good idea in itself if you have a decent router/firewall you'd rather use but is the wrong answer to this particular issue imho...)

swapon failed: Input/output error

Often when I'm at a client's site and need a good, flexible linux toolkit, I use Linux Mint (11 currently) on a usb stick with a 4GB persistent file.

Mostly, the PC's I work on at Client sites have > 512MB. Occasionally I do encounter a PC with less memory and even though I use LXDE (lightweight desktop environment) I run out of memory pretty rapidly. (Web Browsers especially...)

A quick run of "free" shows 0 swap and confirms why applications are silently vanishing:

total used free shared buffers cached