Network troubleshooting: Difference between revisions
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m (Mip moved page Network to Network troubleshooting: There are already a network page. This one is only about troubleshooting.) |
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Revision as of 05:59, 8 June 2016
Troubleshooting network issues
- Ping DNS server
8.8.8.8 Google DNS server 195.238.2.21 Belgacom DNS server
- Ping gateway (see netroute)
Can't connect to SMTP server
I can connect to smtp server locally:
nc localhost 25
220 www.immie.org ESMTP Exim 4.84_2 Mon, 06 Jun 2016 20:28:47 +0200
But when using the IP address, it does not work:
nc immie.org 25
immie.org [91.134.134.85] 25 (smtp) : Connection refused
The firewall is configured to accept connections though:
iptables -L|grep smtp
ACCEPT tcp -- anywhere anywhere tcp multiport dports smtp,submission
In fact, we have a DNS issue:
nc -v -v immie.org 25
DNS fwd/rev mismatch: immie.org != vps282013.ovh.net immie.org [91.134.134.85] 25 (smtp) : Connection refused sent 0, rcvd 0