1 Topic by shaheerep

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Topic: Internet issue happens with email server connected

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Hi,

We have a small setup with 10 computers and PBX & IP Phones connected to the switch which is inturn connected to the DSL Internet router. Also Iredmail server is connected to the same switch.

Now what we are facing is, sometimes PC's cannot access to the internet. we noticed that whenever we removed the email server network cable from the switch, PC's can access to the internet.  After restarting the email server, everything is back to normal.
But I'm in doubt that it will happen again the same issue.

is it anything related to email server?

Could anyone please guide me what would be the issue and some points related to troubleshoot the issue.

Thanks in Advance..

Shaheer

----

Spider Email Archiver: On-Premises, lightweight email archiving software developed by iRedMail team. Supports Amazon S3 compatible storage and custom branding.

2 Reply by ZhangHuangbin

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Re: Internet issue happens with email server connected

Sounds like your users had some password failures (or other errors) and it triggered Fail2ban (on iRedMail) to invoke iptables to block your client IP address. I suggest you add you internal network IP address/net in Fail2ban as whitelist, or, disable fail2ban service as temporary solution.

3 Reply by shaheerep

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Re: Internet issue happens with email server connected

Will Fail2ban service in iredmail server will block the internet access on PC's?

4 Reply by 7t3chguy

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Re: Internet issue happens with email server connected

If the server is used as a switch or router then yes, but if it is an end-point client itself then it cannot easily affect the network upstream

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5 Reply by shaheerep

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Re: Internet issue happens with email server connected

7t3chguy wrote:

If the server is used as a switch or router then yes, but if it is an end-point client itself then it cannot easily affect the network upstream

Thank you for your comments and time...

please note that We have also installed BIND DNS server on this email server.  so it might be the issue.
Will the issue from DNS server or fail2ban service? how can i check these?
what command for temporary stop the fail2ban service and release the blocked IP's?

Kindly guide as i'm newbie to this..

Thanks in Advance....

6 Reply by 7t3chguy

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Re: Internet issue happens with email server connected

Is the DNS Server set to be used by all the machines or the router? You can check iptables using `iptables -L` it'll list all the fail2ban bans too

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7 Reply by shaheerep

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Re: Internet issue happens with email server connected

I have checked iptables and also added lan internal ip to fail2ban.
but still the issue exist.
automatically blocking the internet and will work only after the server restart.

Could anyone please guide me or any other point to check it out?
is there any perticular log i can check?
Please advise...

Thank you in advance....

8 Reply by 7t3chguy

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Re: Internet issue happens with email server connected

Reinstall the OS. See whether it occurs without iRedMail. If it doesn't then reinstall iRedMail and then we can help you. Because there's pretty much no way for iRedMail to cause this.
You should try a tool like Wireshark
or maybe some internal monitoring platform for your switch

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9 Reply by shaheerep

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Re: Internet issue happens with email server connected

Thank you for your quick reply.

Reinstalling the whole system is not applicable now since it's running system and users are using for their emails.

Any perticular log/section need to check in the server?

As you said, will check the internal switch.

10 Reply by 7t3chguy

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Re: Internet issue happens with email server connected

If the server can cause your switch to screw up then find out what its doing on the switch, the server doesn't log all of its network traffic as this log would be huge near-instantly.

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