Port 2049 NFS · TCP and UDP

What runs on port 2049

NFS: Unix network file system. NFSv4 needs only this port (TCP), which makes it firewall-friendly; NFSv3 additionally needs rpcbind (111), mountd, statd and lockd on ports that float unless pinned. Security is "AUTH_SYS" trust-the-client-UID by default; Kerberos (sec=krb5p) is what makes it safe on a shared network, and NFS should never be exposed to the internet either way.

Software that uses it: Linux NFS server (nfs-kernel-server) · TrueNAS, Synology, QNAP · NetApp · Amazon EFS, Google Filestore · Kubernetes NFS volumes

Should port 2049 be open?

Private network or VPN only. Nothing good comes from this port being reachable from the internet. Keep it on an internal network, reach it over a VPN or an SSH tunnel, and firewall it from everything that does not need it.

• showmount -e server lists exports (v3); for v4, mount the root (server:/) and look.
• Restrict exports by address and use root_squash; those two lines prevent most NFS disasters.

Check port 2049

# on the host: is anything listening, and which process?
ss -ltnp 'sport = :2049'
ss -lunp 'sport = :2049'
sudo lsof -i :2049

# from another machine: is it reachable?
nc -zv host 2049
nmap -p 2049 host
nc -zuv host 2049
sudo nmap -sU -p 2049 host
curl -v telnet://host:2049      # raw TCP connect test, Ctrl-C to leave

A port that answers from the internet when it should not is the finding; nmap from a machine outside your network (or a VPS) is the honest test, because scans from inside the LAN pass the firewall you are trying to verify.

Allow or block port 2049

# ufw (Ubuntu/Debian)
sudo ufw allow from 10.0.0.0/8 to any port 2049 proto tcp
sudo ufw allow from 10.0.0.0/8 to any port 2049 proto udp
sudo ufw deny 2049/tcp
sudo ufw deny 2049/udp

# nftables
nft add rule inet filter input ip saddr 10.0.0.0/8 meta l4proto { tcp, udp } th dport 2049 accept
nft add rule inet filter input meta l4proto { tcp, udp } th dport 2049 drop

# iptables (legacy)
iptables -A INPUT -p tcp --dport 2049 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p tcp --dport 2049 -j DROP
iptables -A INPUT -p udp --dport 2049 -s 10.0.0.0/8 -j ACCEPT
iptables -A INPUT -p udp --dport 2049 -j DROP

# firewalld
sudo firewall-cmd --permanent --add-rich-rule='rule family=ipv4 source address=10.0.0.0/8 port port=2049 protocol=tcp accept'

Replace 10.0.0.0/8 with the networks that need access. Allowing by source address is the rule that matters; "allow 2049" with no source is just "open".

Related ports

• 111 rpcbind / portmapper — NFS and other ONC RPC services
• 445 SMB — Windows file sharing, Samba
• 873 rsync — rsync daemon

Part of the port number reference. Ports are 16-bit numbers; see also the subnet calculator and the packet decoder, which shows ports inside TCP and UDP headers.

Questions