CentOS 6.9服务器sudo命令失效问题排查与修复求助

Hey there, let's break down this sudo error you're hitting on your HostGator CentOS 6.9 server. I've dealt with this exact issue a handful of times, so here's the lowdown on what's happening and how to fix it.

What's Causing This? #

That error message boils down to one critical problem: the sudo program has lost its setuid (SUID) permission bit.

Normally, sudo relies on this SUID bit to let regular users temporarily gain root (UID 0) privileges when they run it. Without that bit, sudo can't elevate your permissions, so it throws this error instead of executing your command.

Common reasons this happens:

• You (or someone with server access) accidentally messed up the permissions on /usr/bin/sudo (like running chmod commands that stripped the SUID bit)
• A system glitch or filesystem issue reset the file permissions unexpectedly
• On rare occasions, malicious activity—but for HostGator servers, accidental misconfiguration is way more likely.

How to Fix It #

First off: you need root access to resolve this. Since sudo isn't working right now, you'll have to log in directly as the root user (HostGator provides root credentials for VPS/dedicated servers). If you can't log in as root, reach out to HostGator's support team—they can handle this fix for you quickly.

Once you're logged in as root:

1. Run this command to restore the SUID bit to the sudo binary:

   chmod u+s /usr/bin/sudo
   

2. Double-check that the fix worked by verifying the file permissions:

   ls -l /usr/bin/sudo
   

   You should see output starting with -rwsr-xr-x—the s in the owner permissions column confirms the SUID bit is back in place.
3. Switch back to your regular user (or open a new SSH session with your non-root account) and test sudo again—try something like sudo ls /root to confirm it works without the error.

内容的提问来源于stack exchange，提问作者Naveed Sheriffdeen