On Wed, Jun 17, 2020 at 8:52 AM Mark Reynolds <mreynolds@redhat.com> wrote:

On 6/16/20 6:07 PM, Chris Herdt via FreeIPA-users wrote:

On Tue, Jun 16, 2020 at 12:58 PM Chris Herdt <cherdt@umn.edu> wrote:

I have an appliance that I want to use with our FreeIPA-provided LDAP servers. The appliance only supports the following ciphers:

TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384 (0xc024)
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256 (0xc023)
TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA (0xc00a)
TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA (0xc009)

I tried changing the following in dse.ldif, based on http://www.port389.org/docs/389ds/design/nss-cipher-design.html:

nsSSL3Ciphers: +all

This should allow all the ciphers that the NSS supports.Keep in mind you do need to restart the server after changingnsSSL3Ciphers.

Run this ldapsearch:

# ldapsearch -D "cn=directory manager" -W -xLLL -b cn=encryption,cn=config nsSSLEnabledCiphers nsSSLSupportedCiphers

This will show what is available to the server, and what is enabled. Do you see your ciphers in the available list and/or enabled list?

Thanks for your reply! Yes, I see the ciphers listed both in the available and enabled lists. Excerpt:

nsSSLEnabledCiphers: TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384::AES::SHA384::256

nsSSLSupportedCiphers: TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384::AES::SHA384::2
56

However, a connection using those ciphers fails:

openssl s_client -connect freeipa-01.example.com:636 -cipher ECDHE-ECDSA-AES256-SHA384

(According to https://testssl.sh/openssl-iana.mapping.html, OpenSSL uses ECDHE-ECDSA-AES256-SHA384 for 0xc024.)

Additionally, the nmap script I mentioned previously checks for the ciphers supported by the appliance (as well as others), but does not find the matching ciphers on the LDAP server.

It appears I overlooked an error with the openssl s_client output when specifying the desired cipher, so I've included the output below in case it is helpful. (I added the -servername as I saw several forum posts indicating the error may be due to SNI.)

$ openssl s_client -connect freeipa-01.example.com:389 -starttls ldap -cipher ECDHE-ECDSA-AES256-SHA384 -servername freeipa-01.example.com
CONNECTED(00000003)
140205386876816:error:14077410:SSL routines:SSL23_GET_SERVER_HELLO:sslv3 alert handshake failure:s23_clnt.c:769:
---
no peer certificate available
---
No client certificate CA names sent
---
SSL handshake has read 104 bytes and written 183 bytes
---
New, (NONE), Cipher is (NONE)
Secure Renegotiation IS NOT supported
Compression: NONE
Expansion: NONE
No ALPN negotiated
SSL-Session:
Protocol : TLSv1.2
Cipher : 0000
Session-ID:
Session-ID-ctx:
Master-Key:
Key-Arg : None
Krb5 Principal: None
PSK identity: None
PSK identity hint: None
Start Time: 1592520534
Timeout : 300 (sec)
Verify return code: 0 (ok)
---

I should note the connection succeeds with a number of other ciphers. I appears the server supports the ciphers, but the connection still fails.

So can try to do:

nsSSL3Ciphers: +all,+TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA384,+TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA256,+TLS_ECDHE_ECDSA_WITH_AES_256_CBC_SHA,+TLS_ECDHE_ECDSA_WITH_AES_128_CBC_SHA

Restart the server, check that ldapsearch command to see if these ciphers are now enabled.

HTH,

Mark
However, this enabled only the following 7 ciphers (based on the output of nmap --script ssl-enum-ciphers -p 636 freeipa-01.example.com):

TLS_DHE_RSA_WITH_CAMELLIA_128_CBC_SHA TLS_DHE_RSA_WITH_CAMELLIA_256_CBC_SHA TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256 TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384 TLS_RSA_WITH_CAMELLIA_128_CBC_SHA TLS_RSA_WITH_CAMELLIA_256_CBC_SHA TLS_RSA_WITH_SEED_CBC_SHA

Here's the content of the dn: cn=encryption,cn=config section:

dn: cn=encryption,cn=config
CACertExtractFile: /etc/dirsrv/slapd-EXAMPLE-COM/CN3dUSERTrust20RSA20Certif
ication20Authority2cO3dThe20USERTRUST20Network2cL3dJersey20City2cST3dNew20Jer
sey2cC3dUS.pem
allowWeakCipher: off
cn: encryption
createTimestamp: 20181108213233Z
creatorsName: cn=server,cn=plugins,cn=config
modifiersName: cn=server,cn=plugins,cn=config
modifyTimestamp: 20181108213359Z
nsSSL3Ciphers: +all
nsSSLClientAuth: allowed
nsSSLSessionTimeout: 0
objectClass: top
objectClass: nsEncryptionConfig
sslVersionMin: TLS1.2
numSubordinates: 1

Any ideas why this change isn't enabling the additional ciphers? Thanks!

I should have mentioned, my FreeIPA servers are running ipa-server 4.6.6 on CentOS 7.8.
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