Port 111ONC RPC (SunRPC)
ONC RPC (SunRPC) is a protocol developed by Sun Microsystems enabling remote procedure calls over a network. It serves as the foundational communication method for Network File System (NFS) and other distributed network services on UNIX systems. It supports both TCP and UDP transports to facilitate flexible and efficient inter-process communication between clients and servers in heterogeneous environments..
- transport
- tcp · udp
- in transit
- cleartext
- assignment
- official
- risk
- 4/10
- lookups
- 7,703
2 transports registered
payload readable on path
registered with iana
caution
rank 663 of 993 · top 67%
Technical Details
what runs on :111Overview
ONC RPC, also known as SunRPC, is a framework for executing procedures on remote systems as if they were local calls. It uses an external data representation (XDR) language to ensure interoperability across different hardware architectures. RPC programs register with a portmapper running on port 111, enabling clients to query the port numbers assigned to active services.
Protocols and Transports
Operating over both TCP and UDP, ONC RPC provides flexibility depending on network reliability and latency considerations. UDP is generally preferred for lightweight, low-latency communication, while TCP ensures greater reliability for larger data transfers. Protocol serialization with XDR ensures platform independence for data exchanged.
Use Cases and Dependencies
The most notable use of ONC RPC is as the communication backbone for NFS (Network File System), which allows file access across networks as if they were local filesystems. Beyond that, ONC RPC supports many administrative and network services in UNIX/Linux ecosystems, where it acts as the glue for distributed client-server operations.
Security Information
exposure of :111risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
remote access averages 4.0 across 110 ports — this one sits level with it.
in transit
cleartext
credentials and payloads are readable by anyone on path
assignment
official
registered with iana for this service — scanners fingerprint it by number
reachable over
tcp · udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
Common Vulnerabilities
- Portmapper enumeration: Attackers frequently exploit the portmapper to identify active RPC services, which can be used to plan further exploitation.
- Buffer overflow vulnerabilities: Historical implementations of RPC services have suffered from buffer overflows that could enable remote code execution.
- Unauthenticated access: Many legacy RPC services lack strong authentication, exposing services like NFS to data leakage or unauthorized access.
- Denial-of-Service (DoS): Flooding RPC services can disrupt operations or cause resource exhaustion.
Mitigations
- Restrict access: Limit port 111 exposure via firewall rules to trusted hosts only.
- Disable unused RPC services: Reduce attack surface by stopping unneeded RPC-based services.
- Use TCP Wrappers and Access Controls: Implement host-based access to restrict communication.
- Encryption wrappers: Since ONC RPC lacks native encryption, use VPNs, SSH tunnels, or NFSv4 with Kerberos to secure communications.
- Patch regularly: Keep RPC-related services updated against known vulnerabilities.
- Monitor and audit: Continuously monitor RPC traffic and audit logs for unusual activities.
Related Ports
the 8 most looked-up other ports in remote access — 110 ports carry that label.
| port | service | risk | |||
|---|---|---|---|---|---|
| :8000 | Intel Remote Desktop / Alternate HTTP Port | TCP | Web Services | safe | 84.3k |
| :8888 | D2GS Admin Console | TCP | Remote Access | caution | 83.7k |
| :8881 | Atlasz Secure Server | TCP | Web Services | caution | 67.6k |
| :5938 | TeamViewer | TCPUDP | Remote Access | caution | 65.0k |
| :8291 | Winbox MikroTik Admin | TCP | Security | caution | 62.9k |
| :8008 | IBM HTTP Server Admin | TCP | Web Services | caution | 58.3k |
| :135 | Microsoft EPMAP | TCPUDP | Security | caution | 51.9k |
| :23 | Telnet | TCP | Remote Access | caution | 34.8k |
risk mix of the 8 listed
- safe13%
- caution88%
0 of 8 encrypted