Is port open automatically on linux?


New Member
I have an application to deliver the traffic from Server-A to Server-B.
On Server-A : delivers traffic though from port 10000 till port 19000 randomly
On Server-B (Centos 7)
- receives the traffic from port 10000 till port 19000
- no firewall installed and no restriction on a specific port on this server

During the test, I need to capture the traffic on Server-B using tcpdump : tcpdump -i eth1 portrange 10000-19999 -s0 -w /tmp/pcap-test.pcap

In order to test the traffic delivery from Server-A to Server-B :
- Should I open the port (from port 10000 till port 19000) on Server-B? Or the port will open automatically since no firewall on Server-B?
If yes, how to open multiple ports using range on Centos 7?
- Should I use Socat command to open the port?

Last edited:


Well-Known Member
Usually not. All of the major distro's I am aware of have firewalls.

In CentOS 7 you can use iptables. I myself prefer firewall-cmd.

Depending on where the files are and what permission they have you may also
have play with SElinux permissions.


Gold Member
Gold Supporter
In CentOS 7 you can use iptables. I myself prefer firewall-cmd.
nftables is the new thing, firewalld use it as well as it is a front-end for nftables.
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