I've just fixed a long running problem I've had running exim on RH7.2
It seems that the 2.4.18 kernel that was running on this box was setting the
TCP flag ECN on.
This prevented it from connecting to the following hosts:
mobile.att.net
easycare.com
cox.com
tdsecurities.com
airgatepcsa.com
BCBST.com
cmocanada.com
lewcosec.com
davidsbridal.net
99% of other hosts worked fine.
I had worked around the problem by routing the mail to another mail server
which could reach these hosts.
The problem can be solved by adding
net.ipv4.tcp_ecn = 0
To sysctl.conf
This turns off the ECN flags and everything started working again.
Steve Bates
Accurate Software Ltd
The Courtyard, Denmark Street, Wokingham, RG40 2AZ, UK.
Tel: +44 (0)118 977 3889
Fax +44 (0)118 977 1260
Web: http://www.accurate.co.uk
The information in this email is confidential and privileged and is intended only for the use of the individual or entity listed above. If you are neither the intended individual, or entity listed above, nor the person responsible for the delivery of this email to the intended recipients, you are hereby notified that any unauthorised distribution, copying or use of this email is prohibited. If you have received this email in error, please notify the Accurate system manager at postmaster@accurate.co.uk or on +44 (0)118 977 3889. The views expressed in this communication may not necessarily be the views held by the Accurate Group.
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It seems that the 2.4.18 kernel that was running on this box was setting the
TCP flag ECN on.
This prevented it from connecting to the following hosts:
mobile.att.net
easycare.com
cox.com
tdsecurities.com
airgatepcsa.com
BCBST.com
cmocanada.com
lewcosec.com
davidsbridal.net
99% of other hosts worked fine.
I had worked around the problem by routing the mail to another mail server
which could reach these hosts.
The problem can be solved by adding
net.ipv4.tcp_ecn = 0
To sysctl.conf
This turns off the ECN flags and everything started working again.
Steve Bates
Accurate Software Ltd
The Courtyard, Denmark Street, Wokingham, RG40 2AZ, UK.
Tel: +44 (0)118 977 3889
Fax +44 (0)118 977 1260
Web: http://www.accurate.co.uk
The information in this email is confidential and privileged and is intended only for the use of the individual or entity listed above. If you are neither the intended individual, or entity listed above, nor the person responsible for the delivery of this email to the intended recipients, you are hereby notified that any unauthorised distribution, copying or use of this email is prohibited. If you have received this email in error, please notify the Accurate system manager at postmaster@accurate.co.uk or on +44 (0)118 977 3889. The views expressed in this communication may not necessarily be the views held by the Accurate Group.
This E-mail has been virus checked by 'Knowledge Checker' http://www.imhotek.com