Author: Peter Bruderer

Get telnet and ftp client back on macOS High Sierra

Apple, in their ultimate wisdom, have removed telnet and ftp client on macOS High Sierra.

It is true. You should not use these commands anymore to do unencrypted management on switches.

But …

For a network administrator these are extremely important to do debugging and troubleshooting.

Get your telnet back:

First, install Xcode from the App Store.

Then open a terminal and get inetutils from the GNU site:

curl -o inetutils-1.9.4.tar.gz

Then compile it yourself:

tar xvzf inetutils-1.9.4.tar.gz
cd inetutils-1.9.4
sudo make install

the clients are now in /usr/local/bin.

Ubuntu do-release-upgrade reconnect

Usually I do a release upgrade over the network, using ssh with the command


For some reasons the connection to host I’m upgrading dies.

No panic. Reconnect to the host with ssh. If it does not work, try port 1022.

Then execute the following command:

screen -ls
here is a screen on:
    root/1234.ubuntu-release-upgrade-screen-window   (09/15/2014 07:48:02 AM)    (Detached)
1 Socket in /var/run/screen/S-root.

Now try to reconnect with

screen -d -r root/1234.ubuntu-release-upgrade-screen-window

The connection is established again and you can continue where you were.

How Do I Update The Root Hints Data File for BIND Named Server?

My local nameserver root zone file is outdated. It has no information about IPv6 and recently changed root server IP address.

How do I update my root hints data file on a Linux server?

You can download it:

wget --user=ftp --password=ftp -O /etc/bind/db.root

Or you can generate it yourself:

dig +bufsize=1200 +norec NS . | egrep -v ';|^$' | sort > /etc/bind/db.root

After all, refresh the name server:

rndc reload

After all the content of the file looks like this:

.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS
.			518400	IN	NS	518400	IN	A	518400	IN	AAAA	2001:503:ba3e::2:30	518400	IN	A	518400	IN	AAAA	2001:500:84::b	518400	IN	A	518400	IN	AAAA	2001:500:2::c	518400	IN	A	518400	IN	AAAA	2001:500:2d::d	518400	IN	A	518400	IN	A	518400	IN	AAAA	2001:500:2f::f	518400	IN	A	518400	IN	A	518400	IN	AAAA	2001:500:1::53	518400	IN	A	518400	IN	AAAA	2001:7fe::53	518400	IN	A	518400	IN	AAAA	2001:503:c27::2:30	518400	IN	A	518400	IN	AAAA	2001:7fd::1	518400	IN	A	518400	IN	AAAA	2001:500:3::42	518400	IN	A	518400	IN	AAAA	2001:dc3::35

This is a current list of the root name servers.

Cisco err-disable recovery

Did it also happen to you, that a port of a remote switch went to err-disable and you had to drive to that location to reset it?

Or you have users in meeting rooms, who plug in the same network cable in two different switch ports? Nothing happened, spanning-tree portfast bpduguard enable was set.  But the ports went down, and nobody realised it?

You can avoid this problem with the setting

errdisable recovery cause all
errdisable recovery interval 180

With this setting, the switch brings up the port after 180 seconds. If the problem still exists, the port goes into err-disable again. If it is fixed, the port comes up again.

Fortigate CLI Shortcuts

Fortigate offers some helpful features on the command line to position the cursor.

up arrow, CTRL-PPrevious command
 down arrow, CTRL+N Next command
CTRL-A Beginning of line
 CTRL-E End of line
 CTRL-B Back one word
 CTRL-F Forward one word
 CTRL-D Delete current Character
 CTRL-C Abort Command and exit Branch(be careful: CTRL-C is context sensitive. It moves you up to the previous command branch level. If you are already at the top, it logs you out
CTRL-L Clear screen
TABCompletes the current word or iterates through the folioing words
?Possible commands