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I am installing Atlassian's Confluence 4.2 on a clean Ubuntu 12.04 server. Confluence runs on Tomcat 6, and uses PostgreSQL 9.1 as its datastore. I've installed and configured phpPgAdmin to manage PostgreSQL, and Zentyal to manage the server generally. Both these applications use Apache.

The problem that I am experiencing is that while I can access phpPgAdmin and Zentyal without problem from a remote PC, I can only access Confluence when running locally (either specified by localhost, IP address or host name). Instead I get an HTTP 502 Connection Failed error.

By way of experimentation, I also installed Ajenti, which appears to use lighttpd rather than Apache or Tomcat, and it too works fine when connected to locally, but gives me the same HTTP 502 error when connected to remotely. So applications served from Apache work fine, but applications served from other services do not - does that ring a bell with anyone? It's been over 10 years since I last sysadmin'ed a Linux box, so I'm more than a little rusty!

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It turns out that there was something wrong with my iptables configuration that was blocking remote access at the firewall. I had added ports 8000, 8080 and 8090 by hand, but it wasn't working; so I saved the iptables configuration, and noticed that the relevant section was:

-A INPUT -j iglobal
-A INPUT -p icmp ! -f -m icmp --icmp-type 8 -m state --state NEW -j ACCEPT
-A INPUT -p icmp ! -f -m icmp --icmp-type 0 -m state --state NEW -j ACCEPT
-A INPUT -p icmp ! -f -m icmp --icmp-type 3 -m state --state NEW -j ACCEPT
-A INPUT -p icmp ! -f -m icmp --icmp-type 4 -m state --state NEW -j ACCEPT
-A INPUT -p icmp ! -f -m icmp --icmp-type 11 -m state --state NEW -j ACCEPT
-A INPUT -p icmp ! -f -m icmp --icmp-type 12 -m state --state NEW -j ACCEPT
-A INPUT -j idrop
-A INPUT -p tcp -m tcp --dport 8090 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 8080 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 8000 -j ACCEPT

Moving the -A INPUT -j idrop to the end of this section seems to have fixed the issue.

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Thank a lot for answering your own question. It is very helpful for me I was asked same [problem][1].Your answer resolve it [1]:…. – xrcwrn Sep 23 '15 at 10:17

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