telnetは対話型での実行が可能で、それに付随して特殊文字が設定されています。
それらは"display"にて確認可能です。
実際のところ
telnet> display will flush output when sending interrupt characters. won't send interrupt characters in urgent mode. will send login name and/or authentication information. won't skip reading of ~/.telnetrc file. won't map carriage return on output. will recognize certain control characters. won't turn on socket level debugging. won't print hexadecimal representation of network traffic. won't print user readable output for "netdata". won't show option processing. won't print hexadecimal representation of terminal traffic. echo [^E] escape [^]] rlogin [off] tracefile "(standard output)" flushoutput [^O] interrupt [^C] quit [^\] eof [^D] erase [^?] kill [^U] lnext [^V] susp [^Z] reprint [^R] worderase [^W] start [^Q] stop [^S] forw1 [off] forw2 [off] ayt [^T]
