> For the complete documentation index, see [llms.txt](https://docs.nexthink.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.nexthink.com/platform/ja/references/references-classic/database-information-and-organization-classic/status-of-tcp-connections-classic.md).

# TCP接続の状態（クラシック）

TCP connection のステータスは以下のいずれかです：

**確立済み (established)**\
リモート側がTCP connectionを受け入れ、まだアクティブです。

**閉じられた (closed)**\
システムはTCP connection が正常に確立された後で閉じました。

**サービスなし (no service)**\
リモート側は最初のSYNメッセージに対してRSTメッセージで応答しました。たとえば、リモート側は存在していますが、リクエストポートにサービスがバインドされていない場合です。ほとんどのpersonal computerは、安全なポートスキャンを防ぐためにRSTメッセージを破棄するファイアウォールで保護されています。

**ホストなし (no host)**\
リモート側はSYNメッセージに応答しません、たとえばリモート側が存在しない、またはファイアウォールによって保護されている場合です。

**拒否された (rejected)**\
operating system 自体がTCP connectionを拒否しました、たぶんセキュリティ設定のためです。


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