sudo grep -r telnet /etc
/etc/services:telnet		23/tcp
/etc/services:rtelnet		107/tcp				# Remote Telnet
/etc/services:rtelnet		107/udp
/etc/services:telnets		992/tcp				# Telnet over SSL
/etc/services:telnets		992/udp
/etc/services:tfido		60177/tcp			# fidonet EMSI over telnet