Port 518NTalk
NTalk is a communication protocol used primarily for sending and receiving simple text messages interactively over Unix-based systems. Operating over UDP, it enables real-time chatting functionality across networked systems, serving as an early example of networked instant messaging. Despite its historical significance, NTalk is largely obsolete today, superseded by more sophisticated and secure messaging platforms..
- transport
- udp
- in transit
- cleartext
- assignment
- official
- risk
- 4/10
- lookups
- 5,363
single transport
payload readable on path
registered with iana
caution
rank 888 of 993 · top 89%
Technical Details
what runs on :518NTalk (Network Talk) is a protocol and service designed for real-time, text-based communication between users across networked Unix systems. It extends the original 'talk' program, facilitating interactive chat sessions. The protocol operates over UDP port 518 for communication between client programs and the server daemon, known as ntalkd.
When a user initiates a session, the NTalk client sends a request packet via UDP to the remote machine’s ntalkd. The daemon then notifies the recipient, and upon acceptance, sets up a full duplex communications path—exchanging UDP packets containing the typed messages. NTalk relies on quick, connectionless datagram exchanges to facilitate low-latency, real-time chat, but does not guarantee delivery or ordering inherent to UDP.
Today, NTalk remains mostly of historical or academic interest. Modern chat systems utilize more robust protocols with built-in encryption, authentication, and features like multi-user chat. However, understanding NTalk provides insight into the evolution of networked communication services.
Security Information
exposure of :518risk score
4/ 10caution
worth attention. how exposed you are depends on configuration — don't leave it reachable from the internet without a reason.
network services averages 3.9 across 604 ports — this one sits 0.1 above.
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
udp
udp is connectionless — source addresses are trivially spoofed and it is a reflection favourite
security overview
-
Common Vulnerabilities:
- Lack of Encryption: All NTalk messages are transmitted in plaintext, making them susceptible to eavesdropping.
- Spoofing and Replay Attacks: Without authentication, attackers might impersonate users or replay messages.
- Denial of Service (DoS): Since it uses UDP, NTalk can be targeted with spoofed or malformed packets to overload the daemon.
- Service Misuse: Attackers can use NTalk to harass users by sending repeated or unwanted messages.
-
Common Mitigations:
- Disable NTalk services unless explicitly needed, as it is largely obsolete.
- Employ network firewalls to block inbound/outbound UDP port 518 by default.
- Monitor and log any unexpected usage of port 518 for signs of malicious activity.
- Use secure, authenticated, and encrypted messaging protocols as modern replacements to mitigate eavesdropping and spoofing risks.
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risk mix of the 8 listed
- caution100%
0 of 8 encrypted