ERROR 2002 (HY000): Can't connect to local MySQL server through socket after removing some packages

Roman Rdgz

5/19/24, 8:23 AM

So, my Security department requested me to remove some unused packages from a certain Ubuntu machine, as their presence is a security risk in case some intruder get access:

/usr/bin/g++
/usr/bin/gcc
/usr/bin/gdb
/usr/bin/make
/usr/bin/nc
/usr/bin/netcat
/usr/bin/perl

Right after their removal, access to MySQL server was lost. AT first the service wask masked, so I unmasked it and started agian. Tried restarting the service, and even uncommented the socket line in a cnf file to make sure the socket was created at /var/lib/mysql/mysql.sock ... but none of that worked.

I don't know if one of those packages was actually required by the mysql server or if this is a strange coincidence, but some advice on what to try would be great.

1 + 1

mysql

guiverc

5/19/24, 8:35 AM

How are we to help? You've not provided any Ubuntu product/release details; nor package details on what MySQL package you refer to, so are we to guess? Packages are built for specific releases (esp. *deb* packages) thus release really matters? or are you asking about *snap* packages (that are the same for all releases?).

Score:2

Ubuntu

vidarlo

5/19/24, 8:35 AM

If you look at the dependencies of MySQL, Perl is listed. MySQL thus needs Perl according to the dependency tree of Ubuntu packagers.

Perl is a scripting language that traditionally has been used for a lot of stuff, so removing it is not a good idea.

If you used apt to remove perl, it should have complained about this.

<Rant>

I'd say this approach to security is cargo cult security at best. Removing the binaries listed will not make it a lot more difficult, unless you ensure every user writeable location is also noexec. Even then it's of minimal value; show me a working modern unix system without Python or a shell capable of control structures...

Removing netcat means that I'll have to spend thirty seconds to write a netcat implementation in python - which is a language you can't remove and have a working Ubuntu system.

</Rant>

+ 4

Jos

5/19/24, 8:45 AM

Hear hear. Writing a simple client-server system (which is basically what `netcat` is) is lesson 1 in network programming in any language. That would mean that every general-purpose language and shell ought to be removed from the system, rendering the system unmaintainable.

vidarlo

5/19/24, 8:46 AM

@Jos - Yep. Removing that is cargo cult security because someone saw in a book that it can be used for nefarious purposes.

Jos

5/19/24, 3:05 PM

If you remove `perl`, why wouldn't the apt system remove `mysql` as well?

vidarlo

5/19/24, 4:52 PM

My guess is that he either didn't use `apt` to remove it (but just `rm`), or that MySQL is not installed via apt or a mechanism that checks dependencies.

Elon Musk

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EN: ERROR 2002 (HY000): Can't connect to local MySQL server through socket after removing some packages

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