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I'm a systems administrator for Windows in a Linux-Centric environment.

I've been trying to set up an LDAP server for our linux workstations, thus far everything has gone relatively well. I decided on 389 DS since it had a lot of extensions that made things I had taken for granted in AD much easier. Now we've begun testing systems against it, and for things like web applications (that use the java LDAP libraries - or so I'm told, I'm not a dev) and Jabber server it all works as you'd expect.

However, for Linux client machines (well, they're actually servers) once I configure them for LDAP they make an obscene amount of connections to the LDAP server. Or at least what seems obscene to me (upwards of 60 connections if X is installed, for no GUI it's 4 or 5). I've noticed that every BASH shell I open when logged in as an ldap user opens a new connection and for every application I launch in the GUI, a new connection is opened as well.

I've tried tweaking the net.ipv4.tcp keepalive related settings as per the 389 DS documentation but that didn't really change anything.

Also, I've noticed that in my netstat, the connections that stay open are listed as 'tcp6' even though when I do a -n they come up as ipv4 addresses - which confuses me.

One last note I disabled ipv6 as well with no effect.

Does anybody have experience with LDAP auth in Ubuntu and is able to tell me if this is normal or not? With my single test machine it seems to work fine but if I add 20 - 30 clients that could hit 600 connections...

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You can enable caching. I don't recall if 389 is all nslcd-based or if it incorporates sssd now, but see if the nscd package is available and enabled. That could probably help with the connection count.

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