Ports are shown as openedin firewall-cmd, but nmap scans shows they are closed

dinstar

7/1/23, 6:11 AM

I am using OpenSuse Leap 15.3, with vicibox v10. I have surfed vicidial fourms, but it seems to be an issue with OpenSuse. I have opened ports with firewall-cmd, following are the output.

vicibox10:~ # sudo firewall-cmd --list-all
public (active)
  target: default
  icmp-block-inversion: no
  interfaces: eth0 home
  sources: 
  services: apache2 apache2-ssl asterisk dhcpv6-client rtp ssh
  ports: 10000-20000/udp 10000-20000/tcp 20001-25000/tcp 20001-25000/udp 5060-5062/tcp 5060-5062/udp
  protocols: 
  forward: no
  masquerade: no
  forward-ports: 
  source-ports: 
  icmp-blocks: 
  rich rules:

Following is the nmap output:

vicibox10:~ # nmap -sU -p 10000 localhost
Starting Nmap 7.70 ( https://nmap.org ) at 2022-03-01 11:37 IST
Nmap scan report for localhost (127.0.0.1)
Host is up (0.000051s latency).
Other addresses for localhost (not scanned): ::1

PORT      STATE  SERVICE
10000/udp closed ndmp

Nmap done: 1 IP address (1 host up) scanned in 0.28 seconds

As nmap scans of UDP are time consuming, hence I scan for random ports in the opened ports range.

I have been stuck with this since past 4 days. I have checked with some udp online scan website too, they are not accessible over WAN too. I need to access them over WAN.

Any help will be appreciated. Thanks

0 + 0

port

opensuse

firewalld

Ron Maupin

7/1/23, 6:19 AM

Whether or not a firewall allows traffic through a protocol/port does not mean there is actually a process that has claimed and opened the port. Also, remember that UDP does not set up connections the way TCP does, so you probably will not get a response to the probe of a UDP port. TCP _should_ respond to such a probe with a RST (telling that there is a listening process) because there is no TCP connection configured with the probe, but it is likely that any listening UDP process simply ignores it. It is difficult to test open UDP ports.

dinstar

7/1/23, 6:46 AM

Hey, then what else can I do? I can connect softphone over LAN, but it disconnects over WAN with error saying that no RTP activity was detected. I am very confused. I have forwarded ports on my router too to the server internal IP.

Zareh Kasparian

7/1/23, 12:16 PM

apart from your question, nc is good tool to test over UDP traffic. "nc -u host.example.com 53". if the port is closed then no result.

Elon Musk

I sit in a Tesla and translated this thread with Ai:

EN: Ports are shown as openedin firewall-cmd, but nmap scans shows they are closed

TH: พอร์ตจะแสดงเป็น openin firewall-cmd แต่การสแกน nmap แสดงว่าปิดอยู่

RO: Porturile sunt afișate ca fiind deschise în firewall-cmd, dar scanările nmap arată că sunt închise

RU: Порты отображаются как открытые в firewall-cmd, но сканирование nmap показывает, что они закрыты

VI: Các cổng được hiển thị dưới dạng đã mở trong tường lửa-cmd, nhưng quá trình quét nmap cho thấy chúng đã bị đóng

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