Port 513Remote Login (rlogin)
**rlogin** (Remote Login) provides remote command-line access to Unix systems, allowing users to log in over the network as if they were directly connected..
- transport
- tcp
- in transit
- cleartext
- assignment
- official
- risk
- 4/10
- lookups
- 10,824
single transport
payload readable on path
registered with iana
caution
rank 399 of 993 · top 40%
1 other service is registered on port 513. compare all 2 →
Technical Details
what runs on :513Remote Login (rlogin) is a classic Unix utility that allows users to establish an interactive text terminal session over a network connection, primarily TCP port 513. Designed as part of the Berkeley r-commands suite, rlogin facilitates seamless remote access between trusted Unix hosts by enabling direct login without repeated password prompts when configured with .rhosts or hosts.equiv files.
Technically, rlogin establishes a TCP-based full-duplex communication channel between a client and a server. Once connected, it forwards terminal input/output, effectively mirroring the remote shell environment. The protocol supports features like window size negotiation and control character exchange, improving interactive usability compared to raw Telnet.
However, rlogin was designed decades ago before network security was a major concern, therefore it transmits all communication, including authentication credentials and session data, in cleartext. This lack of encryption and rudimentary authentication make it obsolete in modern secure network environments, but it remains historically significant.
Security Information
exposure of :513risk 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
every listening transport is another surface to filter at the edge
security overview
Common Vulnerabilities:
- Credentials are transmitted in plaintext, facilitating interception via tools like packet sniffers.
- Trust-based authentication using
.rhostsorhosts.equivcan be trivially spoofed through IP or DNS manipulation. - Susceptible to replay attacks, man-in-the-middle attacks, and impersonation.
- Lacks robust user verification methods found in contemporary protocols.
Common Mitigations:
- Replace rlogin with secure alternatives such as SSH (Secure Shell), which provides encrypted connections and strong authentication.
- Disable rlogin service entirely within networked environments.
- Remove
.rhostsandhosts.equivfiles or restrict them severely. - Enforce network segmentation and firewall rules blocking port 513 from external access.
- Implement strict auditing and monitoring for any residual usage of such legacy protocols.
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