kazulog@sv1:~$ cat /etc/os-release | head -2
PRETTY_NAME="Ubuntu 26.04 LTS"
NAME="Ubuntu"
kazulog@sv1:~$ sudo apt install -y inetutils-telnetd | cat
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.

Reading package lists...
Building dependency tree...
Reading state information...
Solving dependencies...
Installing:
  inetutils-telnetd

Installing dependencies:
  inetutils-inetd  tcpd  update-inetd

Summary:
  Upgrading: 0, Installing: 4, Removing: 0, Not Upgrading: 96
  Download size: 153 kB
  Space needed: 546 kB / 63.1 GB available

Get:1 http://archive.ubuntu.com/ubuntu resolute/universe amd64 tcpd amd64 7.6.q-36build2 [24.6 kB]
Get:2 http://archive.ubuntu.com/ubuntu resolute/main amd64 update-inetd all 4.54build1 [23.0 kB]
Get:3 http://archive.ubuntu.com/ubuntu resolute-updates/universe amd64 inetutils-inetd amd64 2:2.7-2ubuntu1.1 [45.2 kB]
Get:4 http://archive.ubuntu.com/ubuntu resolute-updates/universe amd64 inetutils-telnetd amd64 2:2.7-2ubuntu1.1 [60.6 kB]
Preconfiguring packages ...
Fetched 153 kB in 2s (85.3 kB/s)
Selecting previously unselected package tcpd.
(Reading database ... 91400 files and directories currently installed.)
Preparing to unpack .../tcpd_7.6.q-36build2_amd64.deb ...
Unpacking tcpd (7.6.q-36build2) ...
Selecting previously unselected package update-inetd.
Preparing to unpack .../update-inetd_4.54build1_all.deb ...
Unpacking update-inetd (4.54build1) ...
Selecting previously unselected package inetutils-inetd.
Preparing to unpack .../inetutils-inetd_2%3a2.7-2ubuntu1.1_amd64.deb ...
Unpacking inetutils-inetd (2:2.7-2ubuntu1.1) ...
Selecting previously unselected package inetutils-telnetd.
Preparing to unpack .../inetutils-telnetd_2%3a2.7-2ubuntu1.1_amd64.deb ...
Unpacking inetutils-telnetd (2:2.7-2ubuntu1.1) ...
Setting up update-inetd (4.54build1) ...
Setting up tcpd (7.6.q-36build2) ...
Setting up inetutils-inetd (2:2.7-2ubuntu1.1) ...
Created symlink '/etc/systemd/system/inetd.service' → '/usr/lib/systemd/system/inetutils-inetd.service'.
Created symlink '/etc/systemd/system/multi-user.target.wants/inetutils-inetd.service' → '/usr/lib/systemd/system/inetutils-inetd.service'.
Setting up inetutils-telnetd (2:2.7-2ubuntu1.1) ...
Processing triggers for man-db (2.13.1-1build1) ...
Scanning processes...
Scanning linux images...

Running kernel seems to be up-to-date.

No services need to be restarted.

No containers need to be restarted.

No user sessions are running outdated binaries.

No VM guests are running outdated hypervisor (qemu) binaries on this host.
kazulog@sv1:~$ grep -n telnet /etc/inetd.conf
23:#<off># telnet	stream	tcp	nowait	root	/usr/sbin/tcpd	/usr/sbin/telnetd
kazulog@sv1:~$ systemctl status inetutils-inetd --no-pager | head -9 | cat
○ inetutils-inetd.service - GNU Network Utilities internet superserver
     Loaded: loaded (/usr/lib/systemd/system/inetutils-inetd.service; enabled; preset: enabled)
     Active: inactive (dead) (Result: exec-condition) since Sat 2026-09-12 09:08:41 JST; 7s ago
 Invocation: 5197dfcb6b574992b9abab5f7049d3a7
  Condition: start condition unmet at Sat 2026-09-12 09:08:41 JST; 7s ago
       Docs: man:inetutils-inetd(8)
             https://www.gnu.org/software/inetutils/manual/
    Process: 2629 ExecCondition=grep -qr ^[0-9A-Za-z/] /etc/inetd.conf /etc/inetd.d/ (code=exited, status=1/FAILURE)
   Mem peak: 1.7M
kazulog@sv1:~$ sudo ss -tlnp 'sport = :23'; echo "ss rc=$?"
State                  Recv-Q                  Send-Q                                   Local Address:Port                                   Peer Address:Port                 Process
ss rc=0