close telnet

Story: Your Linux-based home router could succumb to a new Telnet worm, RemaitenTotal Replies: 3
Author Content
jsusanka

Apr 01, 2016
11:36 AM EDT 		have a netgear WNR3500L and it shipped with the telnet port open on both the wan side and lan side.

called support immediately and they denied that their router ships this way.

about a week later they upgraded the firmware and port 23 isn't open any more.

how about the manufacturers use some common sense
dotmatrix

Apr 01, 2016
11:47 AM EDT 		After the TP-Link thing...

I currently have a Buffalo router running DD-WRT. I really only use it as a wireless access point, the routing functions are all turned off except for DHCP forwarding. Once this router dies, I will be building my own from old PCs -- similar to this prior newswire posting:

http://lxer.com/module/newswire/ext_link.php?rid=227712
flufferbeer

Apr 04, 2016
12:00 AM EDT 		@jsusanka

> have a netgear WNR3500L and it shipped with the telnet port open on both the wan side and lan side.

From a bit of initial research, it turns out that partially free open source Linux-based routr firmwares Tomato and OpenWRT could very well support the WNR3500L(V1?, v?) Whichever version it is, BOTH WNR3500L devices have Broadcom BCM4718xxx chips, so I don't see how the Linux/Remaiten worm could as easily wreck these non-ARM and non-MIPS devices.

Of course, once one of these open source Linux-based routr firmwares is successfuly installed, you'd still have to know how to COMPLETELY disable telnet, and actually DO this ASAP to avaoid the problem.

2c
dotmatrix

Apr 04, 2016
11:46 AM EDT 		root access and netstat are your friends:

Check open ports:
  1. Enable ssh and copy your ssh public key over to the DD-WRT router, don't use passwords -- use keys and only keys for ssh
  2. Login with ssh key
  3.   #netstat -l
Of course, you can also verify that telnet is turned off by default by:

   #nvram show |grep telnet
And make sure you find a line that looks like this:

   telnetd_enable=0

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