---
name: "tcp-environ"
section: "5"
platform: "linux"
package: "qmail"
version: "1.06-6.2~deb10u1"
release: "Debian 10 (Buster)"
platforms: ["linux"]
url: "https://new.carta.tech/tcp-environ"
---

# tcp-environ(5)

TCP-related environment variables

## NAME

tcp-environ - TCP-related environment variables

## DESCRIPTION

The following environment variables describe a TCP connection. They are set up by **tcp-env**, **tcpclient**, and **tcpserver**. Note that **TCPLOCALHOST**, **TCPREMOTEHOST**, and **TCPREMOTEINFO** can contain arbitrary characters.

- PROTO

  The string **TCP**.

- TCPLOCALHOST

  The domain name of the local host, with uppercase letters converted to lowercase. If there is no currently available domain name for the local IP address, **TCPLOCALHOST** is not set.

- TCPLOCALIP

  The IP address of the local host, in dotted-decimal form.

- TCPLOCALPORT

  The local TCP port number, in decimal.

- TCPREMOTEHOST

  The domain name of the remote host, with uppercase letters converted to lowercase. If there is no currently available domain name for the remote IP address, **TCPREMOTEHOST** is not set.

- TCPREMOTEINFO

  A connection-specific string, perhaps a username, supplied by the remote host via 931/1413/IDENT/TAP. If the remote host did not supply connection information, **TCPREMOTEINFO** is not set.

- TCPREMOTEIP

  The IP address of the remote host.

- TCPREMOTEPORT

  The remote TCP port number.

## SEE ALSO

[tcpclient(1)](/tcpclient/1.md), [tcpserver(1)](/tcpserver/1.md), [tcp-env(1)](/tcp-env/1.md), [tcp(4)](/tcp/4.md)