Cannot connect to PostgreSQL Remotely on Amazon EC2 instance using PgAdmin - postgresql

Question

I have a micro free tier RHEL 6 instance running and have postgresql 9.2 installed using the yum instructions here:
http://yum.pgrpms.org/howtoyum.php
And I am able connect to the PG server locally using this on server:
03:46:20 root#xxx[~]$ psql -hlocalhost -p5432 -Upostgres
However i've never successfully connected to it outside of box. The error message looks like:
12:11:56 saladinxu#GoodOldMBP[~]$ psql -h ec2-xxx.ap-southeast-1.compute.amazonaws.com -p5432 -Upostgres
psql: could not connect to server: Connection refused
Is the server running on host "ec2-54-251-188-3.ap-southeast-1.compute.amazonaws.com" (54.251.188.3) and accepting TCP/IP connections on port 5432?
I've tried a bunch of different ways. Here's how my configure files look now:
/var/lib/pgsql/9.2/data/postgresql.conf:
...
# - Connection Settings -
listen_addresses = '*' # what IP address(es) to listen on;
# comma-separated list of addresses;
# defaults to 'localhost'; use '*' for all
port = 5432 # (change requires restart)
max_connections = 100 # (change requires restart)
...
/var/lib/pgsql/9.2/data/pg_hba.conf:
# TYPE DATABASE USER ADDRESS METHOD
host all pgadmin 0.0.0.0/24 trust
host all all [my ip]/24 md5
# "local" is for Unix domain socket connections only
local all all peer
# IPv4 local connections:
host all all 127.0.0.1/32 ident
# IPv6 local connections:
host all all ::1/128 ident
I've tried to make the above address to 0.0.0.0/0 but id didn't work.
And every time i made a change i restarted by running this
service postgresql-9.2 restart
In the Security Group of this EC2 instance i can see this rule already:
TCP
Port (Service) Source Action
22 (SSH) 0.0.0.0/0 Delete
80 (HTTP) 0.0.0.0/0 Delete
5432 0.0.0.0/0 Delete
The netstat command shows that the port is already open:
04:07:46 root#ip-172-31-26-139[~]$ netstat -na|grep 5432
tcp 0 0 0.0.0.0:5432 0.0.0.0:* LISTEN
tcp 0 0 :::5432 :::* LISTEN
unix 2 [ ACC ] STREAM LISTENING 14365 /tmp/.s.PGSQL.5432
To answer bma's question:
If I run the nmap command on the server locally it seems to suggest that thru internal DNS it's going to another host where 5432 is open:
10:16:05 root#ip-172-31-26-139[~]$ nmap -Pnv -p 5432 ec2-54-251-188-3.ap-southeast-1.compute.amazonaws.com
Starting Nmap 5.51 ( http://nmap.org ) at 2013-07-22 10:16 EDT
Nmap scan report for ec2-54-251-188-3.ap-southeast-1.compute.amazonaws.com (172.31.26.139)
Host is up (0.00012s latency).
rDNS record for 172.31.26.139: ip-172-31-26-139.ap-southeast-1.compute.internal
PORT STATE SERVICE
5432/tcp open postgresql
Nmap done: 1 IP address (1 host up) scanned in 0.07 seconds
And the iptables command gives the following output
10:16:14 root#ip-172-31-26-139[~]$ iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
25776 14M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
45 1801 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
251 15008 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
35 2016 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT 21695 packets, 5138K bytes)
pkts bytes target prot opt in out source destination
[Edited after adding according to bma's suggestion]
iptables looks like this after the new addition:
11:57:20 root#ip-172-31-26-139[~]$ iptables -nvL
Chain INPUT (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
26516 14M ACCEPT all -- * * 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
0 0 ACCEPT icmp -- * * 0.0.0.0/0 0.0.0.0/0
47 1885 ACCEPT all -- lo * 0.0.0.0/0 0.0.0.0/0
255 15236 ACCEPT tcp -- * * 0.0.0.0/0 0.0.0.0/0 state NEW tcp dpt:22
38 2208 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
0 0 ACCEPT tcp -- * * [my ip] 54.251.188.3 tcp spts:1024:65535 dpt:5432 state NEW,ESTABLISHED
0 0 ACCEPT tcp -- * * 0.0.0.0/0 54.251.188.3 tcp spt:5432 dpts:1024:65535 state ESTABLISHED
Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
pkts bytes target prot opt in out source destination
0 0 REJECT all -- * * 0.0.0.0/0 0.0.0.0/0 reject-with icmp-host-prohibited
Chain OUTPUT (policy ACCEPT 5 packets, 1124 bytes)
pkts bytes target prot opt in out source destination
0 0 ACCEPT tcp -- * * 54.251.188.3 [my ip] tcp spt:5432 dpts:1024:65535 state ESTABLISHED
0 0 ACCEPT tcp -- * * 54.251.188.3 0.0.0.0/0 tcp spts:1024:65535 dpt:5432 state NEW,ESTABLISHED
But i'm still not able to connect (same error). What could be the missing piece here?

Answer 1

I Found the resolution to this problem.
Two things are required.
Use a text editor to modify pg_hba.conf. Locate the line:
host all all 127.0.0.1/0 md5.
Immediately below it, add this new line:
host all all 0.0.0.0/0 md5
Editing the PostgreSQL postgresql.conf file:
Use a text editor to modify postgresql.conf.
Locate the line that starts with #listen_addresses = 'localhost'.
Uncomment the line by deleting the #, and change 'localhost' to '*'.
The line should now look like this:
listen_addresses = '*' # what IP address(es) to listen on;.
Now Just restart your postgres service and it will be able to connect

Answer 2

Do you have a firewall blocking port 5432? A quick nmap shows that it is being filtered.
nmap -Pnv -p 5432 ec2-54-251-188-3.ap-southeast-1.compute.amazonaws.com
Starting Nmap 6.00 ( http://nmap.org ) at 2013-07-21 11:05 PDT
Nmap scan report for ec2-54-251-188-3.ap-southeast-1.compute.amazonaws.com (54.251.188.3)
Host is up (0.19s latency).
PORT STATE SERVICE
5432/tcp filtered postgresql
What does the iptables on your EC2 show for port 5432?
iptables -nvL
[after OP added more details]
Netstat shows that it is listening, but the firewall output doesn't look like the 5432 port is open (I confess to not being much of a network guy). Referring to some of my notes from previous installs, you might need to open up EC2 port 5432 to your IP.
To allow input firewall access, replace YOUR-REMOTE-IP with the IP you are connecting from:
iptables -A INPUT -p tcp -s YOUR-REMOTE-IP --sport 1024:65535 -d 54.251.188.3 --dport 5432 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A OUTPUT -p tcp -s 54.251.188.3 --sport 5432 -d YOUR-REMOTE-IP --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
--outbound access
iptables -A OUTPUT -p tcp -s 54.251.188.3 --sport 1024:65535 -d 0/0 --dport 5432 -m state --state NEW,ESTABLISHED -j ACCEPT
iptables -A INPUT -p tcp -s 0/0 --sport 5432 -d 54.251.188.3 --dport 1024:65535 -m state --state ESTABLISHED -j ACCEPT
What does iptables -nvL list after that. Can you connect?

Answer 3

Looks your pg_hba.conf misses the "+" after the group name. try
# TYPE DATABASE USER ADDRESS METHOD
host all pgadmin+ 0.0.0.0/24 trust
host all all [my ip]/24 md5
The pg_hba.conf explains about user:
The value all specifies that it matches all users. Otherwise, this is either the name of a specific database user, or a group name preceded by +. (Recall that there is no real distinction between users and groups in PostgreSQL; a + mark really means "match any of the roles that are directly or indirectly members of this role", while a name without a + mark matches only that specific role.)