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Port 20048 (mountd)

IANA assigns port 20048 to mountd: NFS mount protocol.

Registered (user) port, 1024-49151 TCPUDP

IANA assignment

Service nameProtoDescriptionAssigneeReference
mountd TCP NFS mount protocol Nicolas Williams -
mountd UDP NFS mount protocol Nicolas Williams -

Registry dates for this port: registered 2010-08-09.

Check what is listening on port 20048

Linux: is anything listening on TCP 20048?
sudo ss -tlnp 'sport = :20048'
Linux: UDP 20048
sudo ss -ulnp 'sport = :20048'
Linux / macOS: which process owns the port
sudo lsof -nP -i :20048
Older Linux / BSD (net-tools)
sudo netstat -tlnp | grep ':20048 '
Windows (Command Prompt)
netstat -ano | findstr :20048
Windows (PowerShell)
Get-NetTCPConnection -LocalPort 20048 -State Listen | Select LocalAddress,OwningProcess

Test it from outside

From another machine
nc -vz -w 5 HOST 20048
From Windows
Test-NetConnection HOST -Port 20048
UDP probe (no reply does not prove it is closed)
nc -vzu -w 5 HOST 20048

Block port 20048 in the firewall

ufw
sudo ufw deny 20048/tcp
iptables
sudo iptables -A INPUT -p tcp --dport 20048 -j DROP
nftables
sudo nft add rule inet filter input tcp dport 20048 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block TCP 20048' -Direction Inbound -Protocol TCP -LocalPort 20048 -Action Block
ufw
sudo ufw deny 20048/udp
iptables
sudo iptables -A INPUT -p udp --dport 20048 -j DROP
nftables
sudo nft add rule inet filter input udp dport 20048 drop
Windows Firewall
New-NetFirewallRule -DisplayName 'Block UDP 20048' -Direction Inbound -Protocol UDP -LocalPort 20048 -Action Block

Related ports

20034nburn-id, nburn_id20046tmophl7mts20049nfsrdma20057avesterra

All port numbers · Open port checker
Assignment data: IANA port number registry (public domain), retrieved 2026-11-10.