Every single time I use sudo it hangs before completing

Question

Whether I get prompted for a password or not, it hangs between accepting the authentication and executing what I asked for. In other words sudo ls will hang for about 60 seconds.

I'm confused about what might be causing this. This is on Centos 5, and I've looked at selinux and set it both to disabled and enabled, but it doesn't seem to have any effect.

score 20 · Accepted Answer · edited Apr 13 '17 at 12:14

20

From @TheAndruu's answer to this question:

This happens if you change the hostname during the install process. To solve the problem, edit the file /etc/hosts

127.0.0.1 localhost localhost.localdomain localhost4 localhost4.localdomain4 [ADD_YOURS_HERE] 
::1 localhost localhost.localdomain localhost6 localhost6.localdomain6 [ADD_YOURS_HERE]

I had exactly the same problem on Fedora 11 and this solved it.

edited Apr 13 '17 at 12:14

Community

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answered Sep 15 '09 at 00:50

gareth_bowles

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I just made sure that my `$HOSTNAME` was set in the `127.0.0.1` line. It worked. Thanks. – dlamblin Sep 15 '09 at 00:59
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BTW `sudo ls` uses the network in what way? – dlamblin Feb 07 '17 at 10:49
This also worked for ubuntu 16.04 - except I had to change the name for 127.0.1.1 - 127.0.0.1 was localhost – Bill Ryder Oct 07 '17 at 01:34
This also worked for PopOS 22.04 (Ubuntu 22.04) – Michał Lepczyński Sep 02 '23 at 00:26
And I have not changed hostname neither during nor after the install. I suspect some package must have edited the hosts file? – Michał Lepczyński Sep 02 '23 at 00:27

score 2 · Answer 2 · answered Apr 01 '13 at 18:23

For me it was krb5-user/config being installed. I noticed this by examining /var/log/auth.log and seeing pam_krb5 attempts before pam_unix. Using apt-get remove to uninstall those packages fixed it. Don't remove those packages if you are on a computer requiring kerberos (pam_krb5) obviously. My sudo hang went from a consistent 30s to 0s.

dcmorse · Answer 3 · 2023-07-21T03:45:24.743

This is hinted at in [Halsafar][1]'s [answer][2], I have Kerberos enabled on my work VPN but it's useless when I'm off it, so I changed the auth module order in /etc/pam.d/common-auth to use pam_unix before pam_krb5:

Before:

auth [success=4 default=ignore] pam_krb5.so ...
auth [success=3 default=ignore] pam_unix.so ...

After:

auth [success=4 default=ignore] pam_unix.so ...
auth [success=3 default=ignore] pam_krb5.so ...

Note that we change the success= numbering to reflect the new order.

This changed my sudo from 30s to 0s as it did in Halsafar's answer. [1]: https://serverfault.com/users/127821/halsafar [2]: https://serverfault.com/a/495196

Changing the success=# numbering is essential too, by the way. After that it worked flawless again. Thanks! — Haini, May 10 '23 at 21:26

score 1 · Answer 4 · answered Jan 25 '12 at 14:53

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The only other thing you may want to check is your /etc/resolv.conf file to make sure you have a proper dns entry in there. I have seen in the past where this can cause delay.

answered Jan 25 '12 at 14:53

mike Sands

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Would you be able to give an example of what a proper DNS entry in /etc/resolv.conf might look like? – Brandon Essler May 11 '20 at 02:37

score 1 · Answer 5 · answered Jun 21 '12 at 15:12

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You should check three things. 1. /etc/hostname 2. /etc/hosts 3. /etc/resolv.conf

I found that my hostname was correct that the hosts file was incorrect and on top of that the resolv.conf needed updating.

answered Jun 21 '12 at 15:12

Paul J. Barrett

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@PaulJBarrett, how exactly did you update your resolv.conf to fix the issue? And in what way was the hosts file incorrect? – Brandon Essler May 11 '20 at 02:40

score 1 · Answer 6 · edited Sep 15 '09 at 01:00

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Sometimes when your default route isn't set, commands like sudo hang.

Try netstat -r to check if the route is set correctly.

Does this machine get its passwords from the local /etc/passwd file or something like ldap?

edited Sep 15 '09 at 01:00

Dennis Williamson

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answered Sep 15 '09 at 00:32

egorgry

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It is not using `ldap`; I think it is using `/etc/passwd` – dlamblin Sep 15 '09 at 00:47
`/etc/passwd` isn't used for auth, it's used for id to name resolution. `/etc/shadow` is used for authentication. – LiraNuna Sep 15 '09 at 02:09

score 0 · Answer 7 · answered Dec 19 '17 at 18:28

On Solaris 10 sudo was hanging for about 30 seconds. With help from truss I was finally able to determine that it was hanging on the quota command which was hanging on an NFS mount. Unmounting the NFS share eliminated the hang. Have not determined what is wrong with the share yet.

score 0 · Answer 8 · answered Jun 06 '19 at 00:17

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In Fedora 30, Snapd causes sudo, su, etc, to become very slow, and also other session related problems.

Uninstalling snapd, if you're at Fedora, is a recommended alternative.

answered Jun 06 '19 at 00:17

notcarlsatan

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Every single time I use sudo it hangs before completing

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