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After Upgrading to Version 11 421 message

Discussion in 'General Discussion' started by NetImp, Jun 21, 2007.

  1. NetImp

    NetImp Registered

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    Almost at the same time as Cpanel being upgraded to 11.++ I started getting the

    421 Too many concurrent SMTP connections; please try again late message while trying to use the smtp (happening on most all domains on my server)

    Is this issue related to the upgrade... my dedicated server provider seems to think it is related to an attack on the smtp port 25, but it started with the upgrade...

    Any insight on this is appreciated..
     
  2. TechGuy

    TechGuy Well-Known Member

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    We're experiencing the same thing. Please reply back if you figure anything out and I'll do the same. :)
     
  3. nettigritty

    nettigritty Well-Known Member
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  4. NetImp

    NetImp Registered

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    Cpanel Staff?

    Do you know if this issue may be Upgrade related?...this is still happening after a week...
     
  5. hostmedic

    hostmedic Well-Known Member

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    netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n

    I may be offbase - however I think this is stating connections to the SMTP server are being rejected due to there already being X number of connections from the same IP.

    Have you investigated the case that the user simply has too many open connections to the SMTP server?

    Code:
    netstat -ntu | awk '{print $5}' | cut -d: -f1 | sort | uniq -c | sort -n
    run that from shell - and you can see how many connections are hitting your server from 1 specific ip

    I hope that helps you at least w/ the beginning digging to the root of this issue.
     
  6. cPanelNick

    cPanelNick Administrator
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    You can always increase the max accepted connections in the exim config editor in whm.


    smtp_accept_max = 100


    is the default.

    Just make it higher if you really need to accept that much mail at once. But if you are getting attacked you'll probably just be making it worse.
     
  7. fastdns

    fastdns Member

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    Hi NetIMP

    How did you resolve this issue ?
     
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