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So I've been working on this problem for a few days and I'm at a loss. I have installed postfix on Debian with the intent of setting up some forwarding addresses for a specific domain. I believe that postfix is setup correctly, but I can't validate yet as I am not able to connect to the server on port 25.

I've updated the iptables to allow for port 25, and still nothing. I realized today that the iptable records were in the wrong order, so I updated them and restarted networking, but I remain unable to connect.

Can you suggest anything else I can test for? I ran mtr tests, but everything comes back positive - no dropped packets. I can't figure out how to run an mtr for port 25, specifically.

Current iptables -L read as such:

Chain INPUT (policy ACCEPT)
target     prot opt source               destination         
fail2ban-ssh  tcp  --  anywhere             anywhere             multiport dports ssh
fail2ban-ssh  tcp  --  anywhere             anywhere             multiport dports ssh
ACCEPT     all  --  anywhere             anywhere            
REJECT     all  --  anywhere             loopback/8           reject-with icmp-port-unreachable
ACCEPT     all  --  anywhere             anywhere             state RELATED,ESTABLISHED
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:smtp
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:imaps
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:http
ACCEPT     tcp  --  anywhere             anywhere             tcp dpt:https
ACCEPT     tcp  --  anywhere             anywhere             state NEW tcp dpt:ssh
ACCEPT     icmp --  anywhere             anywhere             icmp echo-request
LOG        all  --  anywhere             anywhere             limit: avg 5/min burst 5 LOG level debug prefix "iptables denied: "
DROP       all  --  anywhere             anywhere            

Chain FORWARD (policy ACCEPT)
target     prot opt source               destination         
DROP       all  --  anywhere             anywhere            

Chain OUTPUT (policy ACCEPT)
target     prot opt source               destination         
ACCEPT     all  --  anywhere             anywhere            

Chain fail2ban-ssh (2 references)
target     prot opt source               destination         
REJECT     all  --  116.31.116.11        anywhere             reject-with icmp-port-unreachable
REJECT     all  --  221.229.172.111      anywhere             reject-with icmp-port-unreachable
RETURN     all  --  anywhere             anywhere            
RETURN     all  --  anywhere             anywhere

Could Fail2Ban be part of my problem?

dirknibleck
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1 Answers1

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  1. Do you know the postfix process is running?

    sudo postfix status?

  2. Try from localhost:

    telnet localhost 25

Do you get anything positive from this? Unless your IP is 116.31.116.11 or 221.229.172.111 then fail2ban isn't blocking you.

Community
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Dave Smith
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