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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<source lang=bash> |
<source lang=bash> |
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nc localhost 25 |
nc localhost 25 |
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</source> |
</source> |
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But when using the IP address, it does not work: |
But when using the IP address, it does not work: |
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<source lang=bash> |
<source lang=bash> |
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nc immie.org 25 |
nc -v -v www.immie.org 25 |
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</source> |
</source> |
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The firewall is configured to accept connections though: |
The firewall is configured to accept connections though: |
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<source lang=bash> |
<source lang=bash> |
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iptables -L|grep smtp |
iptables -L|grep smtp |
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</source> |
</source> |
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But in fact, exim only listens to localhost interface: |
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<source lang=bash> |
<source lang=bash> |
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netstat -lpn|grep 25 |
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nc -v -v immie.org 25 |
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# tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 23236/exim4 |
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# tcp6 0 0 ::1:25 :::* LISTEN 23236/exim4 |
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</source> |
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So we must reconfigure exim4 to accept connection from any interface. Reconfigure exim4 and make sure that local interface field is empty: |
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<lang=bash> |
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dpkg-reconfigure exim4-config |
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grep dc_local_interfaces /etc/exim4/update-exim4.conf.conf |
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# dc_local_interfaces='' |
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</lang=bash> |
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'''Note''': The <code>DNS fwd/rev</code> mismatch actually comes from a wrong {{file|/etc/hosts}} configuration. This file still contained the old host name: |
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<source lang=bash> |
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cat /etc/hosts |
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# 127.0.0.1 localhost |
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# 91.134.134.85 vps282013.ovh.net vps282013 |
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</source> |
</source> |
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immie.org [91.134.134.85] 25 (smtp) : Connection refused |
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Revision as of 06:23, 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 -v -v www.immie.org 25
# DNS fwd/rev mismatch: www.immie.org != vps282013.ovh.net
# immie.org [91.134.134.85] 25 (smtp) : Connection refused
# sent 0, rcvd 0
The firewall is configured to accept connections though:
iptables -L|grep smtp
# ACCEPT tcp -- anywhere anywhere tcp multiport dports smtp,submission
But in fact, exim only listens to localhost interface:
netstat -lpn|grep 25
# tcp 0 0 127.0.0.1:25 0.0.0.0:* LISTEN 23236/exim4
# tcp6 0 0 ::1:25 :::* LISTEN 23236/exim4
So we must reconfigure exim4 to accept connection from any interface. Reconfigure exim4 and make sure that local interface field is empty: <lang=bash> dpkg-reconfigure exim4-config grep dc_local_interfaces /etc/exim4/update-exim4.conf.conf
- dc_local_interfaces=
</lang=bash>
Note: The DNS fwd/rev mismatch actually comes from a wrong /etc/hosts configuration. This file still contained the old host name:
cat /etc/hosts
# 127.0.0.1 localhost
# 91.134.134.85 vps282013.ovh.net vps282013