我希望 Ubuntu 作为远程服务器，为此我安装了 telnetd：
ngadre@in01-7h4wrf3:~/Documents/release6.6.1/caos$ sudo apt install telnetd -y
[sudo] password for ngadre:
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following package was automatically installed and is no longer required:
gir1.2-goa-1.0
Use 'sudo apt autoremove' to remove it.
The following NEW packages will be installed:
telnetd
0 upgraded, 1 newly installed, 0 to remove and 162 not upgraded.
Need to get 38.8 kB of archives.
After this operation, 114 kB of additional disk space will be used.
Get:1 http://in.archive.ubuntu.com/ubuntu focal/universe amd64 telnetd amd64 0.17-41.2build1 [38.8 kB]
Fetched 38.8 kB in 1s (48.4 kB/s)
Selecting previously unselected package telnetd.
(Reading database ... 227457 files and directories currently installed.)
Preparing to unpack .../telnetd_0.17-41.2build1_amd64.deb ...
Unpacking telnetd (0.17-41.2build1) ...
Setting up telnetd (0.17-41.2build1) ...
Adding user telnetd to group utmp
Note: xinetd currently is not fully supported by update-inetd.
Please consult /usr/share/doc/xinetd/README.Debian and itox(8).
update-inetd: warning: cannot add service, /etc/inetd.conf does not exist
Processing triggers for man-db (2.9.1-1) ...
ngadre@in01-7h4wrf3:~/Documents/release6.6.1/caos$ ps aux | grep inet
root 110 0.0 0.0 0 0 ? I< Apr06 0:00 [inet_frag_wq]
root 3444843 0.0 0.0 7936 2160 ? Ss 18:00 0:00 /usr/sbin/xinetd -pidfile /run/xinetd.pid -stayalive -inetd_compat -inetd_ipv6
netstat -plnt shows that tcp6:23 port is listening but tcp v4 telnet is not listening.
ngadre@in01-7h4wrf3:~/Documents/release6.6.1/caos$ sudo netstat -plnt
Active Internet connections (only servers)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 3338537/cupsd
tcp 0 0 0.0.0.0:5938 0.0.0.0:* LISTEN 4202/teamviewerd
tcp 0 0 127.0.0.1:5939 0.0.0.0:* LISTEN 4202/teamviewerd
tcp 0 0 127.0.0.1:6015 0.0.0.0:* LISTEN 3443323/sshd: ngadr
tcp 0 0 127.0.0.1:6010 0.0.0.0:* LISTEN 3444365/sshd: ngadr
tcp 0 0 127.0.0.53:53 0.0.0.0:* LISTEN 2747323/systemd-res
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1001058/sshd: /usr/
tcp6 0 0 ::1:6015 :::* LISTEN 3443323/sshd: ngadr
tcp6 0 0 ::1:6010 :::* LISTEN 3444365/sshd: ngadr
tcp6 0 0 :::5938 :::* LISTEN 4202/teamviewerd
tcp6 0 0 ::1:631 :::* LISTEN 3338537/cupsd
tcp6 0 0 :::23 :::* LISTEN 3446333/xinetd
tcp6 0 0 :::22 :::* LISTEN 1001058/sshd: /usr/
connecting to telnet using "telnet 192.168.0.10" fails:
ngadre@in01-7h4wrf3:~/Documents/release6.6.1/caos$ telnet 192.168.0.10
Trying 192.168.0.10...
Connected to 192.168.0.10.
Escape character is '^]'.
Connection closed by foreign host.
如何为 ipv4 启用 telnet？
防火墙已禁用，并且我在 iptables 中看不到任何 DROP/DENY 规则。
我的xinetd.conf如下：
defaults
{
# Please note that you need a log_type line to be able to use log_on_success
# and log_on_failure. The default is the following :
# log_type = SYSLOG daemon info
instances = 60
log_on_success = HOST PID
log_on_failure = HOST
cps = 25 30
}
includedir /etc/xinetd.d