Hi Andrew,
If I am understanding the packet logs correctly, the LDAP server is
responding (only inserting the ldap parts of the log entry):
The search:
Lightweight Directory Access Protocol
LDAPMessage searchRequest(2) "ou=MyBusiness,dc=MyCompany,dc=local"
wholeSubtree
messageID: 2
protocolOp: searchRequest (3)
searchRequest
baseObject: ou=MyBusiness,dc=MyComapny,dc=local
scope: wholeSubtree (2)
derefAliases: neverDerefAliases (0)
sizeLimit: 1
timeLimit: 5
typesOnly: False
Filter: (sAMAccountName=testuser)
filter: equalityMatch (3)
equalityMatch
attributeDesc: sAMAccountName
assertionValue: testuser
attributes: 1 item
AttributeDescription: 1.1
[Response In: 557126]
The results:
Lightweight Directory Access Protocol
LDAPMessage searchResEntry(2) "CN=Test
User,OU=SBSUsers,OU=Users,OU=MyBusiness,DC=MyCompany,DC=local" [1 result]
messageID: 2
protocolOp: searchResEntry (4)
searchResEntry
objectName: CN=Test
User,OU=SBSUsers,OU=Users,OU=MyBusiness,DC=MyCompany,DC=local
attributes: 0 items
[Response To: 557125]
[Time: 0.047382000 seconds]
Lightweight Directory Access Protocol
LDAPMessage searchResDone(2) success [1 result]
messageID: 2
protocolOp: searchResDone (5)
searchResDone
resultCode: success (0)
matchedDN:
errorMessage:
[Response To: 557125]
[Time: 0.047382000 seconds]
I did change my ldap base from dc=MyCompany,dc=local when I noticed it
seemed to be querying additional parts of the directory, although I am
quite sure all users are unique. It is now:
ldap_base: ou=MyBusiness,dc=MyCompany,dc=local
With the group and member bases set to DistributionGroups:
ldap_group_base: ou=DistributionGroups,ou=MyBusiness,dc=MyCompany,dc=local
ldap_member_base: ou=DistributionGroups,ou=MyBusiness,dc=MyCompany,dc=local
The LDAP is still mostly laid out as per the MS Small Business Server
2003 way of setting up the schema (but on 2012 R2), I have no idea if it
is normal for an AD installation. The distribution groups ou is one I
added to try to keep my distribution groups away from the security groups.
Anyway, going back to the results, I don't understand this at low level
but you are asking about searchresref and the server seems to be giving
searchResEntry - is this as simple as MS implementing non-standard methods?
But, in searchResEntry, whilst it finds the objectName, which is a DN,
it is returning 0 attributes, so it can't be as simple as ptloader
doesn't understand the response, the response also appears incomplete?
(I have ldap_member_attribute: set and have tried all sorts of
attributes that I know are in the directory, including sAMAccoutName
which we can see it recognises in the search itself).
I already set the debug option on ptloader (forgot to say in first post)
in cyrus.conf:
ptloader cmd="ptloader -d1" listen="var/lib/cyrus/ptclient/ptsock"
And have tried increasing from 1 but as others have reported it does not
seem to affect verbosity. The debug output goes in syslog similar to the
lines I had before although now that I at least have the bind working I
now get:
cyrus/ptloader[63125]: searching ou=MyBusiness,dc=MyCompany,dc=local
with (sAMAccountName=testuser) failed
Now, what is interesting and needs more investigation later, is that if
I disable pts again and use the same imtest command, it first preforms a
bind using the saslauthd user (so I know sasluthd is making the bind),
the results do include searchResRef entries (several, I think because I
am searching a at dc level?) and cyrus goes on to make a subsequent bind
as testuser, using testuser's password (in the pts examples the initial
bind is by the cyrus user, and there is no subsequent bind for the test
user).
I need to make a site visit now so will dig into this some more later.
thanks for your help so far!
Jim
On 16/06/2021 18:45, AndrewHardy via Info wrote:
Hi Jim,
It sounds like you’ve spotted a few issues and have fixed them. I’m
quite interested to know what your imapd configuration is for pts and
also how the configuration knows what OU the user you’re testing
resides in? I haven't personally set up LDAP auth with Cyrus although
it’s been something I’ve been wanting to do for some time (so showing
a bit of interest in this thread).
When you mentioned nothing seems to get returned to ptloader, is it
possible to confirm if there was a ldap response from the user search
in the ldap packet trace?
Was the result count returned and what was the format of searchresref?
If that is returned on the wire (confirming user was found after the
initial search) then I guess next step is to debug ptloader to see
what that’s expecting to receive and whether the ldap response data
gets there ? I’m assuming the search does find the user of interest
and the result count is 1 and the distinguished name of the object is
returned over the wire to the mail server? If the user is searched but
not found, that’s likely a place to investigate e.g where in the tree
is it trying to find the user - does the attribute you’re checking for
and the user searched match up?
For ptloader, there is a debug option. May be worth enabling that
although not sure what that technically offers in terms of
troubleshooting info. Im a bit unsure on how to attach strace in this
context, which process ptloader operates under or whether it’s it’s
own seperate process with its own pid. If it’s the later it’s probably
going to be a bit easier. Bit of trial and error most likely.
Regards
Andrew
Sent from my iPhone
On 17/06/2021, at 03:48, Jim Wallis <[email protected]> wrote:
Hi Andrew,
This has been very helpful. I didn't think of using wireshark before,
it has enabled me to at least sort out a typo in my bind DN , but I
am still not much further on.
With auth_mech: pts commented out, and using an imtest line like:
imtest -u test -a test -w passfortest localhost
I can see from the wireshark capture that Saslauthd is binding as the
test user and imtest authenticates OK
with auth_mech: pts uncommented I need to provide bind credentials in
imapd.conf (I use the ones for my cyrus user so I can tell what is
being passed). This cyrus user binds successefully and looks up the
test user, but nothing seems to get returned to ptloader, so I
probably need to spend more time thinking about what attribute I need
to return (I have tried several likely candidates). It doesn't look
as though saslauthd is used at all when I have pts on. Imtest
responds not authenticated.
More work to do... I guess I need to learn how to use strace.
Thanks
Jim
On 15/06/2021 20:30, AndrewHardy via Info wrote:
Hi Jim,
I’m not sure specifically what your issue is here but I’ll help
provide some options for debugging ldap (specific to the windows
logging question). I’d suggest dropping the TLS 636 LDAPS and just
start with standard LDAP 389, removing TLS complexity whilst you
validate a working configuration.
I’d suggest also just running wireshark on the domain controller
where you expect ldap connections to reach and capture the 389
traffic with a filter of your source mail server (or component doing
the authentication). You’d be able to assess the ldap flow; whether
the server sees it or not (and what the response was from the
server, if any).
You could also open another terminal, open saslauthd with strace and
dump the authentication process to file to analyse what may be
happening. If you can’t wireshark the target authentication service,
you could perhaps tcpdump on the ldap client side, drop that into a
.pcap file then open this in wireshark on your desktop for further
analysis.
I’m hoping those potential options can help verify what is/isn’t
happening. An absence of traffic leaving the server would imply
something on the client side, ruling out the ldap server at fault -
at least initially.
Hope this helps simplify troubleshooting and helps confirm what
is/isn’t happening at least from an ldap perspective. Unsure of
enabling ldap debugging in windows, I’ve searched for that for years
and never really come up with a good solution. Wireshark and/or
tcpdump has helped me solve all problems I’ve had with
ldap/authentication although ldaps can be a bit more problematic
when just using packet tracing software. Can still come in useful
though.
Regards
Andrew
Sent from my iPhone
On 16/06/2021, at 06:30, [email protected] wrote:
It seemed like it would be a good idea to use the existing Active
Directory DC as the LDAP source for all mail users.
I got cyrus (3.2.6 from Buster backports) running using saslauthd
for authentication against the directory, and test users could
authenticate OK and see their mailbox in Thunderbird. relevant
entires in imapd.conf:
allowplaintext: yes
sasl_mech_list: PLAIN
sasl_pwcheck_method: saslauthd
Because I want to use some groups for shared folders and
distribution lists, I also want to authorize users and groups
against the directory so enabled:
auth_mech: pts
pts_module: ldap
ptloader_sock: var/lib/cyrus/ptclient/ptsock
ldap_uri: ldaps:/companydomaincontroller:636
ldap_bind_dn: a cn that works in other binds
ldap_password: the password for above
ldap_sasl: 0
ldap_version: 3
ldap_ca_dir: /etc/ssl/certs (which is where the ca cert that
works with saslauthd resides)
ldap_verify_peer: 1
ldap_base: base that other binds can successfully find users from
ldap_scope: sub
ldap_filter: (sAMAccountName=%u) (I have tried more complex
filters and decided on this as one that should work)
ldap_user_attribute: mail
ldap_size_limit: 1024
I have commented out the group member stuff for now, need to walk
before I can run!
With these options enabled, no one can authenticate, even though my
understanding is that authentication is distinct from
authorization. Thunderbird users can no longer login and imtest for
user cyrus (which is in the directory) gives the same output up to
a line :
C: A01 AUTHENTICATE PLAIN {a hash}
S: A01 NO authentication failure
Authentication failed. generic failure
Security strength factor: 256
(the SSF is reported the same, but I have for now only asked for
level 0)
In /var/log/syslog I find the following lines:
cyrus/ptloader[8230]: ldap_initialize failed (ldaps:/DC:636)
cyrus/imap[8229]: timeout_select exiting. r = 1; errno = 0
cyrus/imap[8229]: timeout_select: sock = 11, rp = 0x7ffecbb6ad30,
wp = 0x0, sec = 30
cyrus/imap[8229]: timeout_select exiting. r = 1; errno = 0
cyrus/imap[8229]: ptload read data back
cyrus/imap[8229]: ptload(): bad response from ptloader server:
ptsmodule_connect() failed
cyrus/imap[8229]: No data available at all from ptload()
cyrus/imap[8229]: ptload completely failed: unable to canonify
identifer: cyrus
cyrus/imap[8229]: SASL bad userid authenticated
cyrus/imap[8229]: badlogin: localhost [::1] PLAIN (-notset-)
[SASL(-6): can't request information until later in exchange:
Information that was requested is not yet available.]
I have been searching for answers for days and at one point found a
reference that claimed ptsloader is not enabled by default in
Debian, so I have downloaded the source package and compiled
cyrus-imaps using a configure script based on the Debain default
config options with some extra options: --with-auth=pts
--with-pts=ldap and --with-ldap
This has made no difference.
I have also downlaoded the 3.4.1 source package from experimental
and compiled with the same options ands still no difference to
behaviour so suspect this is a red herring?
So why is ptloader not retrieving any data?
The ldap_bind credentials I have given it work fine with saslauthd
or postfix or ldapsearch.
Presumably then my filter and user attributes are bad? But I can't
see why.
What is the order of operations within cyrus?
I assume that it authenticates first using saslauthd, and then uses
the same username to check authorization in pts, but enabling PTS
seems to prevent authentication. Although in syslog it is
suggesting that SASL has authenticated, but with a bad userid?
The windows DC uses a directory migrated from an older one on a
small business server where microsoft recommended using an internal
.local domain which has always been a bit of a headache for me.
This means that our search base is a DC=local, as are the bind DN
and userPrincipleName, but the mail and proxyAddresses email
addresses are all .com
Is the problem related to this? do I need to enable virtual domains
and/or cross realm authentication for ptloader to get a response
from the server?
Is there any way to call ptloader outside of master to try to work
out exactly what is being passed and what result it achieves?
Also, how does ptdump work? I get no indication that it has done
anything, is this simply because ptloader has never yet obtained
any data for it to dump?
As for checking the LDAP server logs, if anyone knows how I can do
this on windows 2012 please advise! Looking at directory services
in event viewer I see very few entries and nothing relating to
communication from my mail server. I assume I need to enable a
different log level but I can't find out how or what.
All the examples I can find are based on openldap installations, is
what I am trying to do possible, or are the Active Directory schema
completely incompatible with ptloader?
Jim Wallis
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