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Community ▶ Questions ▶ How do I open a port on my Linode for remote access?
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How do I open a port on my Linode for remote access?

networking firewall iptables development

Hi,

I would like to use linode as a development box.

Rails development server runs on port 3000.

What would be the steps required to open 3000 for remote access.

I tried using

1)Arno Iptables [http://library.linode.com/security/fire … an-5-lenny">http://library.linode.com/security/firewalls/arno-iptables-debian-5-lenny]

2)ufw https://help.ubuntu.com/community/UFW

but i still couldnt access rails server using port 3000

Here are the details for the linode

gauravt@gauravtiwari5050:~$ uname -a

Linux gauravtiwari5050 3.0.4-linode38 #1 SMP Thu Sep 22 14:59:08 EDT 2011 i686 GNU/Linux

gauravt@gauravtiwari5050:~$ lsb_release -a

No LSB modules are available.

Distributor ID: Ubuntu

Description: Ubuntu 10.04.2 LTS

Release: 10.04

Codename: lucid

Kindly help.

7 Replies

Do:

netstat -ltn

to see which TCP ports have listening daemons. Port 3000 should be there.

And do:

iptables -L -n

to see your iptables firewall status.

If the default iptables policy is to 'allow', then port 3000 will be accessible if there's something listening on it.

If the default policy is to reject or deny, then you will need to add a rule to allow access to port 3000. How you do that will depend on the firewall interface you use.

Thanks for the help sleddog.

here is the o/p of netstat

gauravt@gauravtiwari5050:~$ netstat -anp | grep LISTEN | awk '{print $4}' | sed s/".*:"//g | sort -n -u

(Not all processes could be identified, non-owned process info

will not be shown, you would have to be root to see it all.)

ACC

22

25

80

110

143

514

993

995

3000

3306

from o/p of iptable -L -n

Chain ufw-user-input (1 references)

target prot opt source destination

ACCEPT tcp – 0.0.0.0/0 0.0.0.0/0 tcp dpt:22

ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:514

ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:3000

ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:3000

ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:3000

Is there any tutorial/wiki that you could guide me too.

Run the commands

netstat -ltn

iptables -L -n

as root (or sudo) for a complete status picture.

Try stopping/disabling your firewall temporarily. If you can then access your site you know it's a firewall issue.

````
gauravt@gauravtiwari5050:~$ sudo netstat -ltn
[sudo] password for gauravt:
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State
tcp 0 0 0.0.0.0:993 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:514 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:995 0.0.0.0:* LISTEN
tcp 0 0 127.0.0.1:3306 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:110 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:143 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:3000 0.0.0.0:* LISTEN
tcp 0 0 0.0.0.0:25 0.0.0.0:* LISTEN
tcp6 0 0 :::514 :::* LISTEN
tcp6 0 0 :::22 :::* LISTEN 

output of iptables

Chain INPUT (policy DROP)
target prot opt source destination
ufw-before-logging-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-before-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-logging-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-reject-input all -- 0.0.0.0/0 0.0.0.0/0
ufw-track-input all -- 0.0.0.0/0 0.0.0.0/0

Chain FORWARD (policy DROP)
target prot opt source destination
ufw-before-logging-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-before-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-logging-forward all -- 0.0.0.0/0 0.0.0.0/0
ufw-reject-forward all -- 0.0.0.0/0 0.0.0.0/0

Chain OUTPUT (policy ACCEPT)
target prot opt source destination
ufw-before-logging-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-before-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-after-logging-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-reject-output all -- 0.0.0.0/0 0.0.0.0/0
ufw-track-output all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-after-forward (1 references)
target prot opt source destination

Chain ufw-after-input (1 references)
target prot opt source destination
ufw-skip-to-policy-input udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:137
ufw-skip-to-policy-input udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:138
ufw-skip-to-policy-input tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:139
ufw-skip-to-policy-input tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:445
ufw-skip-to-policy-input udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:67
ufw-skip-to-policy-input udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:68
ufw-skip-to-policy-input all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type BROADCAST

Chain ufw-after-logging-forward (1 references)
target prot opt source destination
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK] '

Chain ufw-after-logging-input (1 references)
target prot opt source destination
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK] '

Chain ufw-after-logging-output (1 references)
target prot opt source destination

Chain ufw-after-output (1 references)
target prot opt source destination

Chain ufw-before-forward (1 references)
target prot opt source destination
ufw-user-forward all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-before-input (1 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
ufw-logging-deny all -- 0.0.0.0/0 0.0.0.0/0 state INVALID
DROP all -- 0.0.0.0/0 0.0.0.0/0 state INVALID
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 3
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 4
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 11
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 12
ACCEPT icmp -- 0.0.0.0/0 0.0.0.0/0 icmp type 8
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp spt:67 dpt:68
ufw-not-local all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 224.0.0.0/4 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 224.0.0.0/4
ufw-user-input all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-before-logging-forward (1 references)
target prot opt source destination

Chain ufw-before-logging-input (1 references)
target prot opt source destination

Chain ufw-before-logging-output (1 references)
target prot opt source destination

Chain ufw-before-output (1 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0 state RELATED,ESTABLISHED
ufw-user-output all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-logging-allow (0 references)
target prot opt source destination
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW ALLOW] '

Chain ufw-logging-deny (2 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0 state INVALID limit: avg 3/min burst 10
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10 LOG flags 0 level 4 prefix `[UFW BLOCK] '

Chain ufw-not-local (1 references)
target prot opt source destination
RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type LOCAL
RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type MULTICAST
RETURN all -- 0.0.0.0/0 0.0.0.0/0 ADDRTYPE match dst-type BROADCAST
ufw-logging-deny all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 10
DROP all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-reject-forward (1 references)
target prot opt source destination

Chain ufw-reject-input (1 references)
target prot opt source destination

Chain ufw-reject-output (1 references)
target prot opt source destination

Chain ufw-skip-to-policy-forward (0 references)
target prot opt source destination
DROP all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-skip-to-policy-input (7 references)
target prot opt source destination
DROP all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-skip-to-policy-output (0 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-track-input (1 references)
target prot opt source destination

Chain ufw-track-output (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 state NEW
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 state NEW

Chain ufw-user-forward (1 references)
target prot opt source destination

Chain ufw-user-input (1 references)
target prot opt source destination
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:22
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:514
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:3000
ACCEPT tcp -- 0.0.0.0/0 0.0.0.0/0 tcp dpt:3000
ACCEPT udp -- 0.0.0.0/0 0.0.0.0/0 udp dpt:3000

Chain ufw-user-limit (0 references)
target prot opt source destination
LOG all -- 0.0.0.0/0 0.0.0.0/0 limit: avg 3/min burst 5 LOG flags 0 level 4 prefix `[UFW LIMIT BLOCK] '
REJECT all -- 0.0.0.0/0 0.0.0.0/0 reject-with icmp-port-unreachable

Chain ufw-user-limit-accept (0 references)
target prot opt source destination
ACCEPT all -- 0.0.0.0/0 0.0.0.0/0

Chain ufw-user-logging-forward (0 references)
target prot opt source destination

Chain ufw-user-logging-input (0 references)
target prot opt source destination

Chain ufw-user-logging-output (0 references)
target prot opt source destination

Chain ufw-user-output (1 references)
target prot opt source destination

````

I tried disabling firewall ,using steps given here

https://help.ubuntu.com/community/IptablesHowTo

I am still unable to access the site running on port 3000

What exactly happens when you try to connect to port 3000 on your server? There's something listening on port 3000, and it looks like it's allowed by your firewall, so it ought to be working…

If you've flushed iptables rules so that the 3 default chains (input, forward and output) all show policy 'ACCEPT' then the issue isn't firewall-related.

Which suggests that the problem is with your webserver/rails setup. Afraid I can't help you with that as I don't use rails. Hopefully someone more knowledgeable than me will be along to help :)

It seems that the network that i was in had blocked acces to port 3000.

I was able to get it working in another network.

Thanks a lot sledogg and hoopycat for your help.

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