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trying to understand SID portion in contextCSN
by cYuSeDfZfb cYuSeDfZfb 05 Jul '23

05 Jul '23

Hi! Trying to better understand the contextCSN attribute. ContextCSN is formatted like: TIMESTAMP#COUNT#SID#MOD My question is on the SID part: ServerID. I have the following serverID configuration in our 4-server Multi-Master PoC setup: serverID 222 ldaps://ldapm01.company.com serverID 221 ldaps://ldapm02.company.com serverID 212 ldaps://ldapm03.company.com serverID 211 ldaps://ldapm04.company.com And when I (quick and dirty) check contextCSN using slapcat (I know that ldapsearch is the better way) I get: [root@ldapm04 ~]# slapcat | grep contextcsn -i contextCSN: 20180917142109.765066Z#000000#000#000000 contextCSN: 20230622151102.137085Z#000000#001#000000 contextCSN: 20230622151105.174343Z#000000#002#000000 contextCSN: 20230627112536.529432Z#000000#0dd#000000 contextCSN: 20230627112536.529512Z#000000#0de#000000 The first 2018 contextCSN is irrelevant (it has alwas been there, and I should probably try to get rid of it) but the last four seem to be the "actual" configured replication 'lines' on each node to the other three, like this: syncrepl rid=2?4 provider=ldaps://ldapm0?.company.com:636 bindmethod=simple binddn="cn=replication,ou=Directory Access,o=company,c=com" credentials=very_secret searchbase="o=company,c=com" filter="(objectClass=*)" scope=sub schemachecking=on type=refreshAndPersist retry="60 +" attrs="*,+" tls_reqcert=demand syncrepl rid=2?4 provider=ldaps://ldapm0?.company.com:636 bindmethod=simple binddn="cn=replication,ou=Directory Access,o=company,c=com" credentials=very_secret searchbase="o=company,c=com" filter="(objectClass=*)" scope=sub schemachecking=on type=refreshAndPersist retry="60 +" attrs="*,+" tls_reqcert=demand syncrepl rid=2?4 provider=ldaps://ldapm0?.company.com:636 bindmethod=simple binddn="cn=replication,ou=Directory Access,o=company,c=com" credentials=very_secret searchbase="o=company,c=com" filter="(objectClass=*)" scope=sub schemachecking=on type=refreshAndPersist retry="60 +" attrs="*,+" tls_reqcert=demand Now the actual question: contextCSN displays these SID's: 001, 002, 0dd, 0de. None of which I have configured *anywhere*. Not as a SID, not as a RID, as can be seen above. Yet: all info I can find tells me that the third field of contextCSN is "the SID". Can anyone explain? Are they perhaps HEX? If why the large gap between to consequtive pairs..? Curious :-) Thanks!

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RE: [EXT] Re: What drives CPU usage spikes?
by Quanah Gibson-Mount 03 Jul '23

03 Jul '23

--On Monday, July 3, 2023 2:25 PM +0000 "Windl, Ulrich" <u.windl(a)ukr.de> wrote: > Hi! > > I'm wondering: Did you examine whether some indices might help? Those don't help with the issue being addressed in regards to accesslog databases. --Quanah

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Re: [EXT] Re: Proposal to strengthen slapd EXTERNAL authentication
by Jordan Brown 30 Jun '23

30 Jun '23

On 6/29/2023 11:29 PM, Windl, Ulrich wrote: > I think there's something missing: When *creating* the certificate "It proves that the bearer owns the DN" (done by RA/CA), but when *using* the certificate (by a client) the server should still check whether the certificate matches the client. Otherwise any stolen certificate could be used to gain access from everywhere. MHO. When you say "matches the client", what do you mean? That the client's IP address maps to a name on the certificate? Remember that in DNS the mapping from IP address to name is under the control of the person who owns the IP address, not the person who owns the name. Remember also that the client may be behind a NAT that hides their IP address. Finally, remember that the client may legitimately change its IP address and DNS name (if any) from time to time as it is moved from one location to another (think phone, or laptop, or desktop moving from one office to another) or networks are reconfigured around it. This is asymmetric from the more common server authentication. For server authentication, the server has a stable name, and that name was supplied by the human and so can be trusted (more or less) and checked against the certificate. In fact, that human-supplied name serves exactly the same purpose as an "authorized DN" list: it says which certificates are acceptable. Net... you're absolutely right, if somebody steals your certificate - more precisely, your private key - they can use it to gain access. It is exactly as for a password: a username and password authenticates the user, but if somebody steals your password, they can masquerade as you. Depending on your particular scenario, it might be appropriate to have *additional* checks - acceptable networks, et cetera - or require multiple factors (e.g. certificate plus password). Those additional checks are not part of the certificate-based authentication process. Somebody stealing your private key may well be Game Over. Don't let people steal it. -- Jordan Brown, Oracle ZFS Storage Appliance, Oracle Solaris

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Re: What drives CPU usage spikes?
by David Hawes 30 Jun '23

30 Jun '23

On Fri, 23 Jun 2023 at 12:04, Quanah Gibson-Mount <quanah(a)fast-mail.org> wrote: > > In our 2.6.4 deployment, we had a significant spike in CPU usage one day > last week that lasted approximately 2 hours (8 AM UTC to 10 AM UTC). > During this time, some clients started timing out when talking to the LDAP > service, and search response times spiked as well, up to 9.5 seconds on > searches that normally take < 3 seconds (they do have large result sets). > This happened on all 6 of the read nodes that we have in our load balance > pool, so whatever the issue was hit all of them at the same time. It did > not happen to 2 specialized read nodes that only serve one specific > service, so it was something about the traffic going to those 6 nodes. The > number of ops/second during that time frame was actually lower than usual > across the cluster, with a peak of 200 ops/second. We often have higher > peaks than that without this type of CPU usage spiking. I've noticed similar behavior on large accesslog purges. High CPU, poor response times, sometimes slapd even becomes unresponsive. Do these systems have an accesslog that gets purged?

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SASL for OAuth
by Pascal Jakobi 30 Jun '23

30 Jun '23

Hi there I am reading at the moment RFC 7628 (SASL for OAuth). The idea is to extend usage of OAuth outside of the HTTP world. It has obviously been written with SMTP & IAMP in mind. It seems that it could be a very nice solution for authenticating web frontends accessing dir. servers (typically web based directory browsers). Correct if I am missing a point here, pls. As far as I understand, OL does not support it (again, feel free to correct). Are there any plans to look into it ? Best, P

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RSfd in top, memory, etc.
by Sam Dave 29 Jun '23

29 Jun '23

While I write to an LMDB database, while it gets bigger and bigger, I can see %MEM in top rising steadily. This is because %MEM is composed of three things, including "RSfd". From the top manpage: RSfd -- Resident File-Backed Memory Size (KiB) A subset of resident memory (RES) representing the implicitly shared pages supporting program images and shared libraries. It also includes explicit file mappings, both private and shared. Is it memory mapping that's resulting in the higher RSfd? RSfd increases do not seem to have an effect on "buff/cache" or "avail Mem", i.e. what most people think as "RAM" is not being used up. I still want to ask, could too high RSfd use result in less efficient use of memory for other programs? I'm essentially wondering how efficient common OSes (e.g. MacOS, Linux) are in this area. - Sam

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Proposal to strengthen slapd EXTERNAL authentication
by Sean Gallagher 28 Jun '23

28 Jun '23

I'd like to propose a new feature to substantially strengthen the existing access controls in slapd. This follows on from comments made in the discussion around Issue 10065. In particular Comment 17 and Comment 19. The objective here is to validate the credentials supplied by external security mechanisms BEFORE the main server loop starts, and terminate the connection if the client is not "known". It was noted that the olcAuthzRegexp configuration option already deals with externally supplied Authentication ID. My idea is to build on that. I propose a new flag for "olcDisallows" that is "unmatched_external_authid". Setting this flag would instruct slapd to drop the connection if the externally supplied authid did not match any of the olcAuthzRegexp rules. Currently the olcAuthzRegexp rules are only applied after a command arrives. My proposal does not change that, instead I propose that olcAuthzRegexp be evaluated at "connection time" as well as at "execution time". This would reduce the chance of any unexpected side effects. The only real issue I can think of is - is it possible for olcAuthzRegexp to match an AuthID without changing it. Is there any recursion in the application of these rules? Any thoughts? -- This email has been checked for viruses by AVG antivirus software. www.avg.com

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Re: Proposal to strengthen slapd EXTERNAL authentication
by Howard Chu 28 Jun '23

28 Jun '23

Sean Gallagher wrote: > On 26/06/2023 7:40 pm, Howard Chu wrote: >> That feature is already available using TLSVerifyClient in the slapd config. > > Not really. Using the TLSVerifyClient mechanism could be made to work and would be a nice solution but it isn't there yet. To make this this work, you would > need to pass to libldap, some type of specification of the names of legitimate clients. Then in the tls_o.c:tlso_verify_cb() function, compare the name on the > client cert with the specification and return the pass/fail status back to the TLS layer. Then it would all "just work". > > The average user might be surprised to learn that TLSVerifyClient does not currently involve checking the client's name. You would intuitively think that was > pretty important. The point of a certificate-based authentication system is not to have to implement authentication rules for each and every individual user. An LDAP server should only trust certificates issued by a single CA; that CA should only be issuing certs to valid users. Ideally, the LDAP server should be the CA, which is what slapo-autoca is designed for. An LDAP server is not a web server or a client. There is no reason for it to trust certs from multiple CAs. > >> Pure nonsense. > > Pure hubris. > > It's sad when it takes a disaster to affect real change. Pure ignorance. > > -- -- Howard Chu CTO, Symas Corp. http://www.symas.com Director, Highland Sun http://highlandsun.com/hyc/ Chief Architect, OpenLDAP http://www.openldap.org/project/

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Re: observation on serverID / URI match
by cYuSeDfZfb cYuSeDfZfb 28 Jun '23

28 Jun '23

Hi, Thanks Quanah. Just to follow-up: Yes, with an ldap listener on 0.0.0.0, openldap is *still* able to determine it's own serverID when multiple are configured, based on the above-mentioned code. In my config I do: serverID 1 ldaps://my.ldapserver1.com serverID 2 ldaps://my.ldapserver2.com (nota bene FQDN) and the local hostname is obviously NOT a FQDN but just a (short) hostname. But it is still matched correctly, which is phenomenal, and not something I could read / understand from the docs! :-) I also tested, by changing the config to a non-existing "serverID 2 ldaps:// my.ldapserver5.com <http://my.ldapserver2.com>", and then we do get the "read_config: no serverID / URL match found. Check slapd -h arguments." Impressed by openldap's cleverness. :-) Regards! On Tue, 27 Jun 2023 at 17:40, Quanah Gibson-Mount <quanah(a)fast-mail.org> wrote: > > > --On Monday, June 26, 2023 10:18 PM +0200 cYuSeDfZfb cYuSeDfZfb > <cyusedfzfb(a)gmail.com> wrote: > > > Now we wonder if the serverID is determined and set correctly or > > not.... and even with loglevel -1 the auto-determined "local serverID" > > is not logged on start. > > > > > > Does anyone know? > > > > > > Can the serverID also be determined from the local hostname? Or is there > > any other magic going on? > > > This is determined in the following code block in servers/slapd/config.c: > > < > https://git.openldap.org/openldap/openldap/-/blob/master/servers/slapd/conf… > > > > So that's the magic you are looking for. > > Regards, > Quanah >

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observation on serverID / URI match
by cYuSeDfZfb cYuSeDfZfb 27 Jun '23

27 Jun '23

Hi, In an attempt to standardize our config as much as possible, we included in our slapd.conf: serverID 1 ldaps://my.ldapserver1.com serverID 2 ldaps://my.ldapserver2.com serverID 3 ldaps://my.ldapserver3.com serverID 4 ldaps://my.ldapserver4.com The hostname of the RHEL9 servers is set to ldapserver1 & ldapserver2, but on the hosts slapd is configured to run like: /opt/symas/lib/slapd -d 0 -h ldap:/// ldaps:/// ldapi:/// -u ldap -g ldap (so... NO uri specified, also not in /etc/default/symas-openldap) We expected to receive an error like: no match between serverID and URI found, but much to our surprise we don't. :-) Now we wonder if the serverID is determined and set correctly or not.... and even with loglevel -1 the auto-determined "local serverID" is not logged on start. Does anyone know? Can the serverID also be determined from the local hostname? Or is there any other magic going on? And otherwise... why is everything starting regularly, and are we not getting the error message? (we are running a 4 server multi-master replication setup, and replication with the above setting in place is still working normally)

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openldap-technical