Hello Lynwood, I had in my JNOS virtually a lot of attempts connections to
port 23 from all part of the world, to achieve forwarding to other BBS had
change the telnet port to 2323 and substantially lower these attempts.
When I speak attempts to port 23 are evidence of brute force, it is almost
impossible to have open this port, also same the 20, 21, 443, etc.
73 Gabriel YV5KXE.
Venezuela AmprNet Coordinator
yv5kxe.ampr.org
Date: Thu, 29 Sep 2016 12:15:57 -0400
From: lleachii(a)aol.com
To: 44net(a)hamradio.ucsd.edu
Subject:Date: Thu, 29 Sep 2016 12:15:57 -0400
From: lleachii(a)aol.com
To: 44net(a)hamradio.ucsd.edu
Subject: [44net] Security - Telnet (port tcp/23)
Message-ID: <8c28faa2-76ff-45a9-06c6-1705433cf307(a)aol.com>
Content-Type: text/plain; charset=windows-1252; format=flowed
All,
In June, we discussed a topic entitled: "Odd Username attempts at login"
where Bill, KG6BAJ noticed odd connection attempts to his JNOS system
via Telnet.
I have recently been working on my SNMP and NetFlow servers, and noticed
quite a bit of Telnet connection attempts from Asia, Europe and South
America. While I have also seen SSH, RDP, NTP, ICMP and VNC, by far the
largest amount of traffic reaching my border interface is Telnet.
Doing some research, I discovered that NIC.CZ <http://nic.cz/> has been
operating the
Turris Project. They have determined that these attempts are coming from
a botnet of embedded devices that have Telnet vulnerabilities.
I have provided a link to those findings here:
https://en.blog.nic.cz/2016/09/01/telnet-is-not-dead-at-
least-not-on-smart-devices/
09-28 19:57:36 0.000 TCP 60.189.137.98:28940 -> 44.60.44.128:2323
09-28 19:57:55 0.000 TCP 115.219.124.37:49067 -> 44.60.44.133:23
09-28 19:57:55 0.000 TCP 222.124.85.17:34905 -> 44.60.44.133:23
09-28 19:57:52 5.552 TCP 190.67.215.114:29593 -> 44.60.44.6:23
09-28 19:58:03 0.123 TCP 115.219.124.37:21070 -> 44.60.44.133:23
09-28 19:58:54 0.000 TCP 116.102.62.182:37311 -> 44.60.44.135:23
Please be mindful.
73,
- Lynwood
KB3VWG