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-   -   Openldap disabling SSL Ciphers (https://www.linuxquestions.org/questions/linux-server-73/openldap-disabling-ssl-ciphers-4175543664/)

YankeePride13 05-26-2015 01:47 PM
Openldap disabling SSL Ciphers
 
I'm putting up an instance of OpenLdap for testing purposes. One of the first things I did after I installed the system was run a security scan on the system to see what obvious holes I needed to plug. One of them was that RC4 SSL ciphers were allowed in my instance. I have been searching for how to disable SSL ciphers in openldap (my version uses cn=config style configuration) and haven't found an answer yet. Can someone shed some light? I figured I'd post this here and see if anyone came up with anything while I continue to do research on it.

While we are on the subject, what is the preferred set of Ciphers that everyone is currently using?

YankeePride13 05-26-2015 02:49 PM
So I think I got a little closer. I know that I need to modify the olcTLSCipherSuite attribute. Here's what I have so far:

Code:
ldapmodify -D "cn=admin,dc=example,dc=com" -W -H ldapi:/// -f ./ciphers.ldif
ciphers.ldif:
Code:
dn: cn=config
changetype: modify
replace: olcTLSCipherSuite
olcTLSCipherSuite: HIGH:MEDIUM:!ADH:!MD5:!RC4
When I run the command, I get an error saying :
Code:
modifying entry "cn=config"
ldap_modify: Insufficient access (50)
I know that the credentials are correct because I am able to do an ldap search using the same admin account and password without issue and am able to bind with it. It's the admin user, so it should have the required access. Anyone see what I am doing wrong?

bathory 05-26-2015 03:54 PM
Quote:
modifying entry "cn=config"
ldap_modify: Insufficient access (50)

I know that the credentials are correct because I am able to do an ldap search using the same admin account and password without issue and am able to bind with it. It's the admin user, so it should have the required access. Anyone see what I am doing wrong?
You need a different admin to do changes in cn=config. By default it's cn=admin,cn=config, so try this:
Code:
ldapmodify -D "cn=admin,cn=config" -W -H ldapi:/// -f ./ciphers.ldif
Most likely the password is the same for both admins

YankeePride13 05-27-2015 08:36 AM
Thanks! This was a big help. I had to add the cn=admin,cn=config password but once I did that, I was able to get past the insufficent access issue.

I did run into another issue, however. Apparantly Openldap doesn't like the openssl style cipher names (I.E. HIGH:MEDIUM:!ADH:!MD5:!RC4). It only likes gnutls cipher names. Once i switched the olcTLSCipherSuite to gnutls cipher names, it worked. The only issue now is I have to find out a gnutls cipher list that excludes RC4 based ciphers. If I find it, I'll post it here. If anyone else knows off the top of their head, please let me know!

Thanks again!

YankeePride13 05-27-2015 08:41 AM
Got it:

Code:
olcTLSCipherSuite: SECURE:-VERS-SSL3.0:-ARCFOUR-128


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