Topic: 421 per host concurrency limit reached

[pwinkler]

We are using SME 7.0 final

We have 43 imap clients using outlook

We keep getting this message in outlook:  

"The IMAP server has issued an unrecognized greeting"

and when you click "Details"

"421 per host concurrency limit reached
 Protocol: IMAP
 Server: 192.168.1.3
 Port: 143"

I have searched the forums & tried the following:

* IMAP connection problems and timeouts for no apparent reasons at about more than 30 IMAP boxes

This might help:

    /sbin/e-smith/config setprop imap ConcurrencyLimit 200
    /etc/e-smith/events/actions/imap-conf
    svc -t /service/imap

but as someone else noted there is no imap-conf at /etc/e-smith/events/actions/imap-conf

so we tried this:

config setprop imap ConcurrencyLimit 2000
signal-event email-update

from this thread
http://forums.contribs.org/index.php?topic=30834.0

and this is the current imap cfg (which has not changed despite the above)

 db configuration show imaps
imaps=service
    ConcurrencyLimit=400
    ConcurrencyLimitPerIP=12
    TCPPort=993
    access=public
    status=enabled

Pls help

[JonB]

You are modifying the database for imap but you are showing the database configuration for imaps

Try

db configuration show imap

Jon

[gordonr]

so we tried this:

config setprop imap ConcurrencyLimit 2000
signal-event email-update

The ConcurrencyLimit is the maximum number of IMAP sessions allowed. The ConcurrencyLimitPerIP is the limit for an individual client PC.

So, you have increased the total number of connections, but haven't changed the per-host concurrency limit.

Would you also be able to raise this in the bug tracker? We chose 12 as a decent limit for most networks, but we want to know more about your environment and why you are hitting that limit. Thanks.

[raem]

pwinkler

Note there are both db entries on sme7
config show imap
config show imaps

So when you make db changes, specifiy the correct db entry you wish to change.

[pwinkler]

Thanks for your prompt replies, much appreciated

As I was changing the per ip connection settings ( as suggested by Gordon) it suddenly dawned on me that most of these users are connecting from a windows terminal server and so all the imap connections from that server are using the same IP! Most users have multiple email addresses so i have changed the per IP limit to 150 - don't know if that is going to work until the morning when they start connecting but it seems logical.


BTW what is the differenc between imap & imaps?

[pwinkler]

I have made the following changes:

 db configuration show imaps
imaps=service
ConcurrencyLimit=4000
ConcurrencyLimitPerIP=150
TCPPort=993
access=public
status=enabled

 db configuration show imap
imaps=service
ConcurrencyLimit=4000
ConcurrencyLimitPerIP=150
TCPPort=993
access=public
status=enabled

but we are still experiencing the same prob so I have converted some users with only one email acct to pop3

When only a few people are connected it seems ok but when eveybody connects we get the outlook "The IMAP server has issued an unrecognized greeting"  message repeatedly

Some users have hundreds of mb of emails in multiple folders & multiple email accts and they are the ones that seem to have the most issues with outlook locking up and email transport being slow.

We had the same users on a SME v.6.0.1 custom iso for years that the hardware died on recently that we have now migrated to a new server.

We did have an issue with the v6 but changing the conncurent connections fixed it.

[gordonr]

I have made the following changes:
[...]
ConcurrencyLimitPerIP=150

I think you'll find that 43*12 = 516 which is a lot larger than 150

If all of your users appear to be coming from the same IP you're going to want a value which can handle that.

[CharlieBrady]

I have made the following changes:
[...]
ConcurrencyLimitPerIP=150

I think you'll find that 43*12 = 516 which is a lot larger than 150

If all of your users appear to be coming from the same IP you're going to want a value which can handle that.

Or have a special 'peers' file for that IP address, which allows a special higher per-IP limit. See the ipsvd documentation.

[mdo]

 db configuration show imaps
imaps=service
ConcurrencyLimit=4000
ConcurrencyLimitPerIP=150
TCPPort=993
access=public
status=enabled

db configuration show imap
imaps=service
ConcurrencyLimit=4000
ConcurrencyLimitPerIP=150
TCPPort=993
access=public
status=enabled

That does not look correct to me. You show us the 2 different commands
db configuration show xxxx
but then after the second command which is supposed to show the settings for imap, the output is actually showing the imapS settings!!???
Look at the port. It even says imaps=service

Michael

[pwinkler]

I have now changed the setting to the following, (maybe it's overkill)

[root@mail1 ~]# db configuration show imap
imap=service
    ConcurrencyLimit=40000
    ConcurrencyLimitPerIP=1500
    TCPPort=143
    access=private
    status=enabled

hope this works

[PelgerM]

hello,

i tried this, but it seems that these values are simply ignored....
the same error keeps coming...

the commands

Code: [Select]


config setprop imap ConcurrencyLimit 4000
config setprop imaps ConcurrencyLimit 4000
config setprop imap ConcurrencyLimitPerIP 2000
config setprop imaps ConcurrencyLimitPerIP 2000


output from #db configuration show imap

Code: [Select]


imap=service
    ConcurrencyLimit=4000
    ConcurrencyLimitPerIP=2000
    TCPPort=143
    access=private
    status=enabled


the reason is, that we have actually 2 subnetworks with the mailserver on the old one, with the connection to the internet, and a seperate internal router to connect the 2 networks. i though about pushing the ConcurrencyLimitPerIP high enough so that everyone from the new subnet can access... but still the message

"The IMAP server has issued an unrecognized greeting"

with "Details"

"421 per host concurrency limit reached
Protocol: IMAP
Server: 1.1.1.203
Port: 143"

keeps popin um after a short time...

what have i done wrong?
or is this the totally wrong way?

thanks in advance...

oh, and it is the SME7beta0.9 version... if this could matter...

[byte]

oh, and it is the SME7beta0.9 version... if this could matter...

It's likely to be the problem, as some major bugs have been fixed during that release to final release. Upgrade would be the way to go.

[Tib]

hmm this thread is intersting ...

since I updated my thunderbird it now shows warnings and I get ... You may have exceeded the maximum number of connections to this server... I have 3 Imap mail addresses that I connect to in one hit.

It says that I can try and fix this by lowering the number of cached connections ... so I changed it to 3/imap. This still does not fix it ... 3x3=9

Standard cached connections in Thunderbird is 5 ... so if you have more then one imap account then you already have problems.

SME6.0 never had this problem so something must have changed in SME7.

Now I haven't changed any setting since I installed SME7.0 Final but I did upgrade from I think as low as beta to RC1 to 2 to 3 then final and my configs are as follows:

[edit] Come to think of it I may have changed the ConcurrencyLimit to 400 ... but thats it.

config show imap is:

imap=service
    ConcurrencyLimit=400
    ConcurrencyLimitPerIP=6
    TCPPort=143
    access=private
    status=enabled
   
config show imaps is:

imaps=service
    ConcurrencyLimit=400
    ConcurrencyLimitPerIP=6
    TCPPort=993
    access=public
    status=enabled

so if this is the normal setting then maybe it should be upped a little in the base install to stop problems for a lot of ppl ... I origionally thought it was a Thunderbird problem I had.

I will check the bug tracker for an entry as well.

Regards,

Tib

[Tib]

Just did some more testing

doing a signal-event email-update was not enough.

I had to stop the imap and imaps servers and restart to make the
config setprop imap ConcurrencyLimitPerIP 20
config setprop imaps ConcurrencyLimitPerIP 20

changes to stick.

But even with this setup

imap=service
ConcurrencyLimit=400
ConcurrencyLimitPerIP=20
TCPPort=143
access=private
status=enabled

I still get the same error message when I start up thunderbird ... mind you when I look at the logs there is only a 3/20 connection happening.

after I do a lot of searching of e-mails etc I finnaly get a 9/20 conection

eg:

2006-08-15 21:34:24.145478500 tcpsvd: info: status 9/400
2006-08-15 21:34:24.146008500 tcpsvd: info: pid 18362 from 192.168.1.101
2006-08-15 21:34:24.146012500 tcpsvd: info: concurrency 18362 192.168.1.101 9/20
2006-08-15 21:34:24.146014500 tcpsvd: info: start 18362 0:192.168.1.5 ::192.168.1.101:49923 ./peers/192.168.1
2006-08-15 21:34:24.148512500 imapfront-auth[18363]: * OK imapfront ready.
2006-08-15 21:34:24.153268500 2006.08.15 11:34:24 LOG5[18362:3086969056]: Using 'imap' as tcpwrapper service name
2006-08-15 21:34:24.159624500 2006.08.15 11:34:24 LOG5[18362:3086969056]: stunnel 3.22 on i686-redhat-linux-gnu PTHREAD+LIBWRAP with OpenSSL 0.9.7a Feb 19 2003
2006-08-15 21:34:24.160010500 2006.08.15 11:34:24 LOG5[18362:3086969056]: imap connected from 192.168.1.101:49923

Regards,

Tib

[PelgerM]

well
after updating i get this line repeated every second

Code: [Select]


006-08-15 13:49:19.265986500 ./run: line 10: ./config: No such file or directory
2006-08-15 13:49:20.427042500 ./run: line 10: ./config: No such file or directory
2006-08-15 13:49:21.589507500 ./run: line 10: ./config: No such file or directory
2006-08-15 13:49:22.749384500 ./run: line 10: ./config: No such file or directory
2006-08-15 13:49:23.908219500 ./run: line 10: ./config: No such file or directory


well, i have no idea why...
but, ok... doesn't matter because i stopped imap (/etc/init.d/imap stop)
and the message stops repeating...

the real funny thing is that now, the concurrent connection settings are right and an access tothe imap service is perfectly possible...

If anyone can explain this... wow... i'm really interested in understandig this

[mdo]

2006-08-15 13:49:20.427042500 ./run: line 10: ./config: No such file or directory

This was a problem during the betas - upgrade to SME 7.0 final.
Michael

[mudtoe]

I'm running the final build and I'm having the problem as well.  I upped the settings a lot:

[root@srw-smeserver ~]# db configuration show imap
imap=service
    ConcurrencyLimit=2000
    ConcurrencyLimitPerIP=128
    TCPPort=143
    access=private
    status=enabled
[root@srw-smeserver ~]# db configuration show imaps
imaps=service
    ConcurrencyLimit=2000
    ConcurrencyLimitPerIP=128
    TCPPort=993
    access=public
    status=enabled
[root@srw-smeserver ~]#



However, I'm still getting the error.  I've found this and similar messages in the imap event log:

2006-09-03 02:23:22.930672500 tcpsvd: info: concurrency 3196 172.24.199.215 9/12

Now, I believe that the last two numbers are the in use connections and max connections.  This message came after I changed the settings and rebooted the server.  At the point this message was issued the limit hadn't been reached, but I've seen messages that go up to 13/12, which correspond to the times I'm getting the error message from outlook.  Note, that I have both Outlook and Thunderbird running on the same machine, both connected to SME server (I was doing some testing of the differences between Outlook and Thunderbird IMAP support).  Both have to be running to hit the limit.  In any event it doesn't look like those database configuration settings are effective.  

mudtoe

[mudtoe]

Well, it looks like my previous post got "lost" during the server hiccup yesterday, so I'll put it back.  I can't figure out what template to expand in order to make the database changes mentioned above, take effect.   I ended up editing the imap configuration file directly and restarting the service, which corrected the problem.  

I found pieces of configuration for imap in /etc/e-smith/templates/var/service/imap/config, but whenever I try to do an expand-template on that directory, or any of the items there, it fails.

Anyone know the exact template expand syntax to use for this?


mudtoe

[brianr]

the templates for the imap and imaps services are in:

/etc/e-smith/templates/var/service/imap/config (and for imaps).

so all you need to do is change the db configuration, then expand the above, then restart imap and imaps.

I did this today to "fix" it for a client.

[Tib]

All you have to do to make the changes is the following

Summarized

config setprop imap ConcurrencyLimit 4000
config setprop imaps ConcurrencyLimit 4000
config setprop imap ConcurrencyLimitPerIP 200
config setprop imaps ConcurrencyLimitPerIP 200

signal-event email-update

Stop and start imap and imaps servers.

/etc/init.d/imap stop
/etc/init.d/imap start
/etc/init.d/imaps stop
/etc/init.d/imaps start

or even ... /etc/init.d/imap restart ... will work I think

Then check settings

config show imap
config show imaps

You can also check your imap and imaps log files and you will see eg: 3/200 and 3/4000 connections etc.

Regards,

Tib

[mudtoe]

That did the trick!  I rebooted the server after making the config changes, but I didn't know about the signal-event thing which triggers the template expand.

Thanks much.

mudtoe

[brianr]

Actually the reccommended way to restart a service is to use svc -t now, so here is complete script:

config show imap
config show imaps
config setprop imap ConcurrencyLimit 2000
config setprop imap ConcurrencyLimitPerIP 128
config setprop imaps ConcurrencyLimit 2000
config setprop imaps ConcurrencyLimitPerIP 128
config show imap
config show imaps
expand-template /var/service/imap/config
expand-template /var/service/imaps/config
svc -t /var/service/imap
svc -t /var/service/imaps


I have left a script to do this in my contribs area:

http://mirror.contribs.org/smeserver/contribs/bread/imap/setimap.sh

[andy_wismer]

Hi

Just to report that the script has errors:

#!/bin/sh
#
# Script to set concurrency limits for Imap and Imaps to larger numbers
#
# bjr - 7th September 2006
#
#  http://mirror.contribs.org/smeserver/contribs/bread/imap/setimap.sh
#
config show imap
config show imaps
config setprop imap Concurrency 2000
config setprop imap ConcurrencyIP128
config setprop imaps Concurrency 2000
config setprop imaps ConcurrencyIP 128
config show imap
config show imaps
expand-template /var/service/imap/config
expand-template /var/service/imaps/config
svc -t /var/service/imap
svc -t /var/service/imaps

----------------------------------------------------

Instead of ConcurrencyIP it should read ConcurrencyLimitPerIP or instead of Concurrency it should be ConcurrencyLimit...

[brianr]

Hi Andy

Many thanks for that, actually my "local" copy is correct, I must have updated it locally and then not uploaded it to the contribs directory.

Now sorted...

cheers

Brian

[CharlieBrady]

Actually the reccommended way to restart a service is to use svc -t now,

Not any more. Please use "sv t /service/xxx".

[brianr]

ok, changed that as well....

[NomadOfNorad]

Actually the reccommended way to restart a service is to use svc -t now, so here is complete script:

config show imap
config show imaps
config setprop imap ConcurrencyLimit 2000
config setprop imap ConcurrencyLimitPerIP 128
config setprop imaps ConcurrencyLimit 2000
config setprop imaps ConcurrencyLimitPerIP 128
config show imap
config show imaps
expand-template /var/service/imap/config
expand-template /var/service/imaps/config
svc -t /var/service/imap
svc -t /var/service/imaps


I have left a script to do this in my contribs area:

http://mirror.contribs.org/smeserver/contribs/bread/imap/setimap.sh

The above link now yields a 404 error.  Is there somewhere else to get the latest version of this script?  Or is there a newer, better way to achieve the same results now?

[brianr]

sorry, I cleaned out the contribs area last week, and must have deleted that.

I have re-instated it now..

[NomadOfNorad]

Thankee...

I notice the script now ends with

Code: [Select]

svc -t /var/service/imap
svc -t /var/service/imapswhen according to CharlieBrady it should now be something like

Code: [Select]

sv t /service/xxx which you said you'd fixed in the latest version... the one, I guess, which was accidentally deleted.   

Will the script as is still work ok on version 7.3, or do I need to wait for the corrected version?

BTW, if one wanted to suggest that there be added a way to set variables like this from the server-manager... where would one go here to suggest that?  Bugzilla?  Another subboard here at the forum?

[brianr]

ok, fixed it now - sorry about that.

[NomadOfNorad]

ok, fixed it now - sorry about that.

You sure?  I just now downloaded the file from the link above and compared it with the one from a few hours ago... and they look identical.

[brianr]

You'll need to give it a few hours to sync up, I only did it 15 minutes ago.

In the interim you could edit it yourself?

just change svc -t <whatever>

to sv t <whatever>

[NomadOfNorad]

LOL!

No great hurry.  I'll wait for the change to take effect.  It's nearly 3am here, anyway.   

[NomadOfNorad]

Uh-oh...  it's gone back to 404 again... 

edit: Okay, I've changed my local copy as described above.

[NomadOfNorad]

Well, I ran the script as follows...

Code: [Select]

config show imap
config show imaps
config setprop imap ConcurrencyLimit 2000
config setprop imap ConcurrencyLimitPerIP 128
config setprop imaps ConcurrencyLimit 2000
config setprop imaps ConcurrencyLimitPerIP 128
config show imap
config show imaps
expand-template /var/service/imap/config
expand-template /var/service/imaps/config
sv t /var/service/imap
sv t /var/service/imaps
...and it went all the way to the end of it, and then complained that it could not do the last two lines of it because the path or file didn't exist.  I'm guessing this is either because I ran the script from \\Server\primary\files or because I should have taken the /var out of /var/service/####


In any event, I then performed a system reset from the server-manager interface, since that would then make sure that imap and imaps was running again.  The rest of the day, I didn't having any problems with Thunderbird... but now I'm having the same "Unable to connect to your IMAP server..." problems again.

Is there a script or command I can run to tell me if the changes "took"?

And would something like this prevent my outgoing mails from getting out, even though Thunderbird acts as if they were sent to the outside world?  Today, none of my mails seem to be getting to their destinations...

[brianr]

config show imap
config show imaps

will show you if the changes where made.

I suggest you download the file from my area again (it is there), and apply it.  If you edited the file, then you may have ended up with a "windows" terminated file, not one for linux.

Just refreshed it on the contribs area, leave it a couple of hours to re-sync before downloading

[NomadOfNorad]

Well, invoking config show imap and config show imaps yields:

Code: [Select]

ConcurrencyLimit=2000
ConcurrencyLimitPerIP=128
TCPPort=143
access=private
status=enable
and...

Code: [Select]

ConcurrencyLimit=2000
ConcurrencyLimitPerIP=128
TCPPort=993
access=private
status=enable...respectively.

Does that look right?

[janet]

NomadOfNorad

status=enable

should be
status=enabled
in both cases

[NomadOfNorad]

NomadOfNorad

should be
status=enabled
in both cases

Heh!  Whoops!  Actually it does say "status=enabled" in both cases, I copied it out to the post wrong.  Typo, I guess...

[shawnbishop]

Good Day

I am getting this error on a POP3 connection, I have tried resetting and restarting services and get the 421 concurrency connection , limit reached error

[mmccarn]

I am getting this error on a POP3 connection

You *should* be able to fix this using

Code: [Select]

db setprop pop3s ConcurrencyLimitPerIP 12
sv t pop3s
sv u pop3sHowever, it doesn't look like the POP3 or POP3S services ever access the configuration db for ConcurrencyLimit or ConcurrencyLimitPerIP.

In the short term you can change the per-IP limit by editing /var/service/pop3s/run and changing the "4" to a different value in the line containing -C ${PER_IP_INSTANCES:-4}..., then stopping and restarting the service.

In the long term, you would need to open a bug report requesting db variable control of the various configuration settings for pop3 and pop3s.

[shawnbishop]

Great thanks I will try it