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linux_wiki:configure_a_system_to_forward_all_email_to_a_central_mail_server [2018/05/10 22:41] billdozor [Null Client Testing] |
linux_wiki:configure_a_system_to_forward_all_email_to_a_central_mail_server [2019/05/25 23:50] |
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| - | ====== Configure A System To Forward All Email To A Central Mail Server ====== | ||
| - | |||
| - | **General Information** | ||
| - | |||
| - | Configuring postfix. | ||
| - | |||
| - | On the exam, you will be provided all the information of an already configured central SMTP server. | ||
| - | |||
| - | **You will be expected to configure a null client only**. (server that forwards mail but does not receive any) | ||
| - | |||
| - | ---- | ||
| - | |||
| - | ====== Lab Setup ====== | ||
| - | |||
| - | The following virtual machines will be used: | ||
| - | * server1.example.com (192.168.1.150) -> Configure SMTP null client (**on the exam**) | ||
| - | * server2.example.com (192.168.1.151) -> Configure central mail server for client testing (**NOT on the exam**) | ||
| - | |||
| - | ---- | ||
| - | |||
| - | ====== Null Client Setup ====== | ||
| - | |||
| - | **THIS IS ON THE EXAM**: A mail null client forwards local email. It does not receive any mail from network sources. | ||
| - | |||
| - | **From server1**. | ||
| - | |||
| - | \\ | ||
| - | Install required package | ||
| - | <code bash> | ||
| - | yum install postfix | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Enable and start the postfix service | ||
| - | <code bash> | ||
| - | systemctl enable postfix | ||
| - | systemctl start postfix | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Configure postfix parameters | ||
| - | * Option A: Use postconf (faster if you have an idea what parameters you need to configure)< | ||
| - | postconf relayhost | ||
| - | |||
| - | # check all settings | ||
| - | postconf | grep < | ||
| - | |||
| - | # configure | ||
| - | postconf -e ' | ||
| - | postconf -e ' | ||
| - | postconf -e ' | ||
| - | postconf -e ' | ||
| - | </ | ||
| - | * Option B: Edit the main configuration< | ||
| - | |||
| - | # Relayhost to forward mail to | ||
| - | relayhost = [192.168.1.151] | ||
| - | |||
| - | # Forward from loopback interfaces | ||
| - | inet_interfaces = loopback-only | ||
| - | |||
| - | # Configure destination as blank, because we aren't delivering mail locally (only forwarding outgoing) | ||
| - | mydestination = | ||
| - | |||
| - | # Configure domain | ||
| - | mydomain = example.com | ||
| - | </ | ||
| - | |||
| - | |||
| - | \\ | ||
| - | Check postfix syntax | ||
| - | <code bash> | ||
| - | postfix check | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Restart the service | ||
| - | <code bash> | ||
| - | systemctl restart postfix | ||
| - | </ | ||
| - | |||
| - | ---- | ||
| - | |||
| - | ====== Postfix Central Mail Server ====== | ||
| - | |||
| - | **THIS IS NOT ON THE EXAM**: This section setups up a mail server to receive mail in order to test the null client configured previously. | ||
| - | |||
| - | **From server2** | ||
| - | |||
| - | \\ | ||
| - | Install postfix | ||
| - | <code bash> | ||
| - | yum install postfix | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Enable and start postfix | ||
| - | <code bash> | ||
| - | systemctl enable postfix | ||
| - | systemctl start postfix | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Open the firewall to receive SMTP | ||
| - | <code bash> | ||
| - | firewall-cmd --permanent --add-service=smtp | ||
| - | firewall-cmd --reload | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Edit the main configuration file | ||
| - | <code bash> | ||
| - | #-- vim directly | ||
| - | vim / | ||
| - | |||
| - | # listening interfaces | ||
| - | inet_interfaces = all | ||
| - | |||
| - | # Accept mail for these domains | ||
| - | mydestination = example.com, | ||
| - | |||
| - | #-- postconf method | ||
| - | |||
| - | # check settings | ||
| - | postconf | grep inet_ | ||
| - | postconf | grep mydestination | ||
| - | |||
| - | # configure | ||
| - | postconf -e ' | ||
| - | postconf -e ' | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Check postfix syntax | ||
| - | <code bash> | ||
| - | postfix check | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Restart the service | ||
| - | <code bash> | ||
| - | systemctl restart postfix | ||
| - | </ | ||
| - | |||
| - | ---- | ||
| - | |||
| - | ====== Null Client Testing ====== | ||
| - | |||
| - | **From server1** | ||
| - | |||
| - | Install a mail client (if not already installed) | ||
| - | <code bash> | ||
| - | yum install mailx | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Send a test message | ||
| - | <code bash> | ||
| - | echo "Did it work?" | mail -s "This is a postfix forward test" root@server2.example.com | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Watch the mail log file for status messages | ||
| - | <code bash> | ||
| - | tail -f / | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | **From server2** | ||
| - | |||
| - | On the postfix relayhost, check root's mail | ||
| - | <code bash> | ||
| - | |||
| - | </ | ||
| - | |||
| - | ---- | ||
| - | |||
| - | ====== Troubleshooting ====== | ||
| - | |||
| - | On the sending client, to view the mail queue | ||
| - | <code bash> | ||
| - | postqueue -p | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | Flush the sending mail queue after fixing a problem to get rid of stuck messages | ||
| - | <code bash> | ||
| - | postqueue -f | ||
| - | </ | ||
| - | |||
| - | \\ | ||
| - | If a message is stuck and won't flush, it can be removed | ||
| - | <code bash> | ||
| - | postsuper -d < | ||
| - | </ | ||
| - | * Instead of a single queue_id, you can specify the keyword ' | ||
| - | |||
| - | \\ | ||
| - | On the receiving server, check the maillog for reasons a message did not deliver | ||
| - | <code bash> | ||
| - | tail / | ||
| - | </ | ||
| - | |||
| - | ---- | ||