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How To Open A Port In CentOS / RHEL 7 – GratisVPS

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A TCP/IP community connection could also be both blocked, dropped, open, or filtered. These actions are typically managed by the IPtables firewall the system makes use of and is impartial of any course of or program that could be listening on a community port. This put up will define the steps to open a port required by a utility. For this put up instance, we will likely be opening Utility Particular (Apache) Port 55555.

Server particulars are as beneath:

# uname -a
Linux geeklab 3.10.0-693.17.1.el7.x86_64 #1 SMP Thu Jan 25 20:13:58 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux
# cat /and many others/redhat-release 
CentOS Linux launch 7.4.1708 (Core)

1. Test Port Standing

Test that the port shouldn’t be open and Apache shouldn’t be displaying that port:

# netstat -na | grep 55555
# lsof -i -P |grep http
httpd     5823   root    4u  IPv6  42212      0t0  TCP *:80 (LISTEN)

2. Test Port Standing in iptables

Test that iptables are usually not displaying that port open:

# iptables-save | grep 55555

3. Add the port

Add the check port in /and many others/companies file and permit the port to just accept packets. Take a look at port will be added by modifying /and many others/companies file in beneath format:

# vi /and many others/companies
service-name  port/protocol  [aliases ...]   [# comment]
# vi /and many others/companies
testport        55555/tcp   # Utility Identify

4. Open firewall ports

Add Firewall rule to permit the port to just accept packets:

# firewall-cmd --zone=public --add-port=55555/tcp --permanent
# firewall-cmd --reload
# iptables-save | grep 55555
-A IN_public_allow -p tcp -m tcp --dport 55555 -m conntrack --ctstate NEW -j ACCEPT

5. Test newly added port standing

After including the port for httpd and reloading httpd companies, discover now httpd can also be listening to newly added port 55555:

# lsof -i -P |grep http
httpd     6595   root    4u  IPv6  43709      0t0  TCP *:80 (LISTEN)
httpd     6595   root    6u  IPv6  43713      0t0  TCP *:55555 (LISTEN)
# netstat -na |grep 55555
tcp6       0      0 :::55555                :::*                    LISTEN

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