networking – Centos7 packets filtered without firewalld

I have 2 centos7 servers, I want to create a glusterfs shared volume on both, to do so I need the port 24007 opened on both.

I am testing with nc for the moment. Here server2 is listening to port 24007

root@swarm-node2 ~ # nc -l 24007
root@swarm-node2 ~ # netstat -na | grep 24007
tcp        0      0 0.0.0.0:24007           0.0.0.0:*               LISTEN

On both server firewalld is disabled :

root@swarm-node2 ~ # systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled)
   Active: inactive (dead)

root@swarm-node1 ~ # systemctl status firewalld
● firewalld.service - firewalld - dynamic firewall daemon
   Loaded: loaded (/usr/lib/systemd/system/firewalld.service; enabled; vendor preset: enabled)
   Active: inactive (dead) since Tue 2021-06-08 14:55:42 CEST; 23h ago

With server1 I am trying to connect to port 22 (for testing, it works) then 24007 (it doesn’t):

root@swarm-node1 ~ # nc -zv swarm-node2 22
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connected to @ipsrv2:22.
Ncat: 0 bytes sent, 0 bytes received in 0.24 seconds.

root@swarm-node1 ~ # nc -zv swarm-node2 24007
Ncat: Version 7.50 ( https://nmap.org/ncat )
Ncat: Connection timed out.

I am running a tcpdump on server2 so we can see packets arriving from srv1

root@swarm-node2 ~ # tcpdump -i eth0 -nn port 24007
listening on eth0, link-type EN10MB (Ethernet), capture size 262144 bytes
14:41:20.223909 IP @ipsrv1.54398 > @ipsrv2.24007: Flags (S), seq 2092224680, win 29200, options (mss 1460,sackOK,TS val 85574120 ecr 0,nop,wscale 7), length 0
...
3 packets captured
3 packets received by filter

It says received by filter, I am not sure what is filter at this step (firewalld is off) so it might be iptables ?

I don’t see anything in iptables logs (it is empty even though rsyslog is saying DROP packets should be log) So I added a rule in iptables on srv2 to accept all packets comming from srv1

-A INPUT -s @ipsrv1/32 -i eth0 -m comment --comment "050 allow all from other nodes: 46.105.47.47" -j ACCEPT

As seen by TCPDUMP, packets are arriving to server2 and passed to filter but what is filter here ? firewalld is disabled and iptables should allow or at least log these packets.
Do you have any ways of testing that with more details