NIS server doesn't answer ypbind

There is only 1 NIC on the client - em4. And I have captured the packets by “ping 8.8.8.8” and it can capture the packets.

Yes, it is quite strange that I can get the port 944 with ypserv by rpcinfo command on client, even the NIS master didn’t response:

[root@icetserver01 ~]# rpcinfo -p 10.6.126.20
   program vers proto   port  service
    100000    4   tcp    111  portmapper
    100000    3   tcp    111  portmapper
    100000    2   tcp    111  portmapper
    100000    4   udp    111  portmapper
    100000    3   udp    111  portmapper
    100000    2   udp    111  portmapper
    100005    1   udp  20048  mountd
    100005    1   tcp  20048  mountd
    100005    2   udp  20048  mountd
    100005    2   tcp  20048  mountd
    100005    3   udp  20048  mountd
    100005    3   tcp  20048  mountd
    100024    1   udp  38813  status
    100024    1   tcp  45897  status
    100003    3   tcp   2049  nfs
    100003    4   tcp   2049  nfs
    100227    3   tcp   2049  nfs_acl
    100021    1   udp  33481  nlockmgr
    100021    3   udp  33481  nlockmgr
    100021    4   udp  33481  nlockmgr
    100021    1   tcp  34489  nlockmgr
    100021    3   tcp  34489  nlockmgr
    100021    4   tcp  34489  nlockmgr
 600100069    1   udp    946  fypxfrd
 600100069    1   tcp    946  fypxfrd
    100009    1   udp    950  yppasswdd
    100009    1   tcp    950  yppasswdd
    100004    2   udp    944  ypserv
    100004    1   udp    944  ypserv
    100004    2   tcp    944  ypserv
    100004    1   tcp    944  ypserv

And I think I could not stop ypbind successfully.

[root@icetserver01 ~]# systemctl stop ypbind
[root@icetserver01 ~]# systemctl status ypbind
● ypbind.service - NIS/YP (Network Information Service) Clients to NIS Domain Binder
   Loaded: loaded (/usr/lib/systemd/system/ypbind.service; enabled; vendor preset: disabled)
   Active: failed (Result: exit-code) since Sun 2024-10-20 16:06:19 CST; 1 day 19h ago
  Process: 69013 ExecStartPost=/usr/libexec/ypbind-post-waitbind (code=exited, status=1/FAILURE)
  Process: 69008 ExecStart=/usr/sbin/ypbind -n $OTHER_YPBIND_OPTS (code=exited, status=0/SUCCESS)
  Process: 69005 ExecStartPre=/usr/sbin/setsebool allow_ypbind=1 (code=exited, status=0/SUCCESS)
  Process: 68997 ExecStartPre=/usr/libexec/ypbind-pre-setdomain (code=exited, status=0/SUCCESS)
 Main PID: 69008 (code=exited, status=0/SUCCESS)
   Status: "Processing requests..."

Oct 20 16:05:29 icetserver01 systemd[1]: Starting NIS/YP (Network Information Service) Clients to NIS Domain Binder...
Oct 20 16:05:30 icetserver01 setsebool[69005]: The allow_ypbind policy boolean was changed to 1 by root
Oct 20 16:06:19 icetserver01 systemd[1]: ypbind.service: control process exited, code=exited status=1
Oct 20 16:06:19 icetserver01 systemd[1]: Failed to start NIS/YP (Network Information Service) Clients to NIS Domain Binder.
Oct 20 16:06:19 icetserver01 systemd[1]: Unit ypbind.service entered failed state.
Oct 20 16:06:19 icetserver01 systemd[1]: ypbind.service failed.

Then, when I ypbind -d, the master didn’t answer:

[root@icetserver01 ~]# /usr/sbin/ypbind -d
45135: parsing config file
45135: Trying entry: domain icet server 10.6.126.20
45135: parsed domain 'icet' server '10.6.126.20'
45135: add_server() domain: icet, host: 10.6.126.20, slot: 0
45135: [Welcome to ypbind-mt, version 1.37.1]

45135: ping interval is 20 seconds

45135: rebind interval is 900 seconds

45137: NetworkManager is running.

45137: Network is available.
45137: Switch to online mode
45137: Going online, reloading config file.
45137: parsing config file
45137: Trying entry: domain icet server 10.6.126.20
45137: parsed domain 'icet' server '10.6.126.20'
45137: add_server() domain: icet, host: 10.6.126.20, slot: 0
45137: ping host '10.6.126.20', domain 'icet'
45137: host '10.6.126.20' doesn't answer.
45137: interface: org.freedesktop.DBus, object path: /org/freedesktop/DBus, method: NameAcquired
45140: ping host '10.6.126.20', domain 'icet'
45140: host '10.6.126.20' doesn't answer.
45140: Pinging all active servers.
45140: ping host '10.6.126.20', domain 'icet'
45140: host '10.6.126.20' doesn't answer.
45135: ypbindproc_domain_2_svc (icet)
45135: Pinging all active servers.
45135: ping host '10.6.126.20', domain 'icet'
45135: host '10.6.126.20' doesn't answer.
45135: trylock = success
45135: ping host '10.6.126.20', domain 'icet'
45135: host '10.6.126.20' doesn't answer.
45135: trylock = success
45135: ping host '10.6.126.20', domain 'icet'
45135: host '10.6.126.20' doesn't answer.
45135: Status: YPBIND_FAIL_VAL
45135: ypbindproc_domain_2_svc (icet)
45135: Pinging all active servers.
45135: ping host '10.6.126.20', domain 'icet'
45135: host '10.6.126.20' doesn't answer.
45135: trylock = success
45135: ping host '10.6.126.20', domain 'icet'
45135: host '10.6.126.20' doesn't answer.
45135: trylock = success
45135: ping host '10.6.126.20', domain 'icet'
45135: host '10.6.126.20' doesn't answer.
45135: Status: YPBIND_FAIL_VAL
45140: Pinging all active servers.