LinuxQuestions.org

LinuxQuestions.org (/questions/)
-   Linux - Newbie (https://www.linuxquestions.org/questions/linux-newbie-8/)
-   -   opening ports (https://www.linuxquestions.org/questions/linux-newbie-8/opening-ports-924740/)

snooze1 01-20-2012 01:37 AM
opening ports
 
i am trying to open a UDP port on Centos 5.7 with iptables.

for some reason "iptables -A INPUT -p udp --dport 7777 -j ACCEPT" isn't working.

any suggestions?

aazkan 01-20-2012 03:17 AM
Hi

CentOSes up to CentOS 6 uses the RH-Firewall-1-INPUT chain. It goes like this

Code:
-A RH-Firewall-1-INPUT -p udp -m udp --dport 7777 -j ACCEPT
If you have a service or daemon already running on udp port 7777 try connecting to it with nmap or nc like so

Code:
nmap -nv -sU -p 7777 localhost
or

Code:
nc -nvvv -u localhost 7777
Hope this helps.
Regards,

snooze1 01-20-2012 04:32 AM
Quote:
Originally Posted by aazkan (Post 4579597)
Hi

CentOSes up to CentOS 6 uses the RH-Firewall-1-INPUT chain. It goes like this

Code:
-A RH-Firewall-1-INPUT -p udp -m udp --dport 7777 -j ACCEPT
If you have a service or daemon already running on udp port 7777 try connecting to it with nmap or nc like so

Code:
nmap -nv -sU -p 7777 localhost
or

Code:
nc -nvvv -u localhost 7777
Hope this helps.
Regards,
And do I add that in /etc/sysconfig/iptables?

aazkan 01-20-2012 05:35 AM
Yes. Edit /etc/sysconfig/iptables

or if your cli driven (who isn't), as root, type

Code:
iptables -I RH-Firewall-1-INPUT -p --dport 7777 -j ACCEPT
review it like so

Code:
iptables -L -nv |grep 7777
the nmap or nc test can be use as well.

snooze1 01-20-2012 05:44 AM
Quote:
Originally Posted by aazkan (Post 4579668)
Yes. Edit /etc/sysconfig/iptables

or if your cli driven (who isn't), as root, type

Code:
iptables -I RH-Firewall-1-INPUT -p --dport 7777 -j ACCEPT
review it like so

Code:
iptables -L -nv |grep 7777
the nmap or nc test can be use as well.
Somehow the port is opened now and I can see the server running fine, but when I try and do it with another server running on 9948 UDP adding "-A RH-Firewall-1-INPUT -p udp -m udp --dport 9948 -j ACCEPT" to the file doesn't work.

Also,

Code:
# iptables -I RH-Firewall-1-INPUT -p --dport 9948 -j ACCEPT
iptables v1.3.5: unknown protocol `--dport' specified
Try `iptables -h' or 'iptables --help' for more information.

aazkan 01-20-2012 06:06 AM
From you iptables output/example, your're missing

-p udp

Give it another try?

snooze1 01-20-2012 07:01 AM
Quote:
Originally Posted by aazkan (Post 4579685)
From you iptables output/example, your're missing

-p udp

Give it another try?
First of all, derp..

Code:
#  iptables -I RH-Firewall-1-INPUT -p udp --dport 9948 -j ACCEPT
iptables: No chain/target/match by that name

aazkan 01-20-2012 07:21 PM
Then it means there is no such chain. Have a look in your iptables what chains does it use?

aazkan 01-25-2012 06:23 PM
Hi snooze1,

Thought i chech up with you if you figured out your iptables problem?

tegards,


All times are GMT -5. The time now is 05:25 AM.