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centos6 - iptables outgoing default policy is accept, but some ports appear blocked

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I'm new to servers and iptables. I
have a web app (happens to be bugzilla) running on my Centos 6.7 apache/httpd server,
and it attempts to connect out to the web (updates.bugzilla.org) via port 80. It also
attempts to connect out (to smtp.gmail.com) using port 465. However, it cannot. This is
in spite of having a default output policy of ACCEPT and having opened the relevant
ports for input.



I'm not sure where to go from
here. Where should I look to begin troubleshooting this? What are the likely culprits?




Some
output:




$ service
iptables status



Table:
filter



Chain INPUT (policy
ACCEPT)




num target prot opt source
destination



1 ACCEPT all -- 0.0.0.0/0
0.0.0.0/0



2 ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
state RELATED,ESTABLISHED



3 ACCEPT tcp --
0.0.0.0/0 0.0.0.0/0 tcp dpt:22



4 ACCEPT tcp
-- 0.0.0.0/0 0.0.0.0/0 tcp dpt:80





5 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:443




6 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:25



7 ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp
dpt:587



Chain FORWARD (policy
DROP)
num target prot opt source destination




Chain OUTPUT (policy ACCEPT)

num target prot
opt source destination




AND:





iptables -L -v
Chain INPUT (policy ACCEPT 881 packets, 106K
bytes)



pkts bytes target prot opt in out
source destination




0 0 ACCEPT all
-- lo any anywhere anywhere



436 183K ACCEPT
all -- any any anywhere anywhere state RELATED,ESTABLISHED




0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:ssh



1 60 ACCEPT tcp -- any any anywhere anywhere
tcp dpt:http



0 0 ACCEPT tcp -- any any
anywhere anywhere tcp dpt:https




0
0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:smtp




0 0 ACCEPT tcp -- any any anywhere anywhere tcp dpt:submission



Chain FORWARD (policy DROP 0 packets, 0
bytes)
pkts bytes target prot opt in out source destination



Chain OUTPUT (policy ACCEPT 348 packets,
56741 bytes)




pkts bytes target prot
opt in out source destination




I'm hopeful that
it is not a bugzilla or centos-specific thing, as I have accomplished a successful
bugzilla install on ubuntu desktop, although that was while using ubuntu's ufw (I think
I also tried it with iptables, but would have to try again to
verify).





For those web
searching and seeing this at a later date, it turns out this was a SELinux issue! Needed
to enable the boolean 'httpd_can_network_connect' (for others, use 'getsebool -a').


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Answer




Try
this:




service iptables
            save
service iptables stop
chkconfig iptables
            off


Boom, no firewall.
Test again.



Try using telnet to test that port:




telnet
            updates.bugzilla.org
            80


Once connected with
telnet, type "get" and see if there's a
response.



Example:

#
            telnet updates.bugzilla.org 80
Trying 63.245.223.29... 
Connected to
            updates.bugzilla.org.

Escape character is
            '^]'
get

400 Bad<br />            Request
            bgcolor="white">
400 Bad
            Request

            />
nginx/1.0.15



Connection
            closed by foreign
            host.



Didn't
work?



Try tcptraceroute to see where it gets
blocked:



tcptraceroute
            updates.bugzilla.org
            80


Could there be
something else blocking ports? A firewall, router, ISP?




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