Sudo command hangs

Question

Every time I try to execute sudo su - or any other sudo command for this matter my server hangs, sometimes it take 10 mins to respond and sometimes it never does.

I checked /etc/hosts file which was configured correctly. I also checked /etc/resolv.conf file which looked good as well. any suggestions?

I am running redhat 6.9

Solution 1

Had the same problem on Ubuntu 16.04 on a newly created openstack remote vm. sudo su hanged for many seconds, maybe up to a minute, before it either worked or not. When it worked it could be made quick and reliable by running this once as root:

echo 127.0.0.1 localhost $(hostname) >> /etc/hosts

Solution 2

In my case the problem was caused by multiple sudo processes running/hanging in the background, processes like sudo chmod g+rwx -R folders_with_many_files.

What helped was

ps -aleF | grep sudo

first to inspect, later something like

ps -aleF | grep sudo | awk '{print $4}' | xargs kill -9

Solution 3

The problem can reproduced when the hostname is changed , edit your /etc/hosts by adding the output of echo $HOSTNAME after 127.0.0.1:

127.0.0.1  hostname

Comments

[Admin]

So,  do you have any way of becoming root?

[Admin]

Yes.. Sometimes it allows me to become root

[Admin]

Have you tried running sudo after you’re already root?  Does it still hang then?  If so, you might try running strace (or some similar program) on it.

[Admin]

When does it hang -- before asking for the password or after? (Also, strace sudo -i or so might be your friend, even if its output is daunting, because you can see what it's trying to do when it hangs.)

[Admin]

Possibly related: unix.stackexchange.com/questions/365599/…

[Admin]

@UlrichSchwarz strace is usually a good idea and I almost suggested this myself, but since sudo has the setuid bit set, strace will (should) not be able to attach :-| @Ahmed: if you eventually manage to get root, does it also hang when you do sudo -u $someuser -i? If so, then try that with strace.

[Admin]

Do you have PAM installed. If so, check the config files if you're using some kind of remote authentification (e.g., LDAP)

[Admin]

On your /etc/hosts you shoud have 127.0.0.1 hostname ; hostname =echo $HOSTNAME

[Admin]

@GAD3R I think that resolved my issue

[Ahmed Soliman]

I configured it correctly, the issue was fixed but now its back again for no reason. Not sure what the issue is still :(

[SmallChess]

Same problem. It solved for me.