tags
4. Move pointer past the paragraph
5. Start over till EOF

It worked great overall ! I browsed a few holes like this, and all 
ASCII arts / code snippets rendered perfectly. Actual text paragraphs 
were also pleasant to read with proportional fonts.

However,

A few things I didn't think about looked odd, because the 
 tag 
reflow text by default. Things like lists, or quoted text looked bad:

1. First item 2. Second item 3. Third item

> This was a quoted text with > hard wraps in it, that should 
definitely > not be reflowed.

Some texts or graphic stuff looked odd as well, like banners like this 
that are 70 char wide:

||<><><><><><><....>||

As a conclusion, I think that my « naive » approach was a bit too 
naive, so for now I reverted to full monospace font for the time being, 
until I find a better way to do it, or give up on it entirely.

If someone has an idea, feel free to contact me to discuss it !
--  
~wgs
20200925.1640]]>

               


               

               gopher://phlog.z3bra.org/0/reflowing-emails-with-fmt1.txt

               

               2020-09-09T14:42:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/replacing-tinc-with-wireguard.txt

               

               2021-09-28T18:04:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/rip-microsoft-basic-auth-support.txt

               

               2022-10-25T18:59:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/ssh-as-a-public-service.txt

               

               2022-08-23T17:26:00+02:00

               wgs

                /usr/local/bin/today.sh
	#!/bin/sh
	date '+%A !'
	EOF
	# chmod +x /usr/local/bin/today.sh
	# /usr/local/bin/today.sh
	Tuesday !

You'll probably want something more useful, and we'll get to it later
on. For now, this will be enough.


1. Service account
------------------

It all starts with an account, that you'll use to connect to the 
machine, and run the program. This account must not have a password,
and have restricted rights to the system resources.

So let's first create a login class for these users, to limit its 
resource usage on the system:

	# cat < /etc/login.conf.d/sshervice
	sshervice:\
		:path=/bin /usr/bin /usr/local/bin:\
		:umask=022:\
		:datasize=1024M:\
		:maxproc=32:\
		:openfiles=128:\
		:stacksize=1M:\
		:filesize=512M:
	EOF
	# cap_mkdb /etc/login.conf
	
See login.conf(5) for how to tweak these values to your likings.

	# groupadd _sshervice
	# adduser -d /var/sshervice \
		-L sshervice \
		-g _sshervice \
		-s /bin/sh \
		-p '' \
		today

At this point, you should be able to get a shell for your service 
account without specifying a password (try as non-root user):

	$ su - today
	$ /usr/bin/whoami
	today
	$ pwd
	/var/sshervice


2. SSH access
-------------

You can login as this user, but it shouldn't be accessible from the
outside, because of how unsecure it is (at least that's the case on
OpenBSD).

Thanks to the "Match" keyword, OpenSSH can apply specific configuration
bits to a user or a group (see sshd_config(5) for details). So we'll
use that:

	# cat < /etc/ssh/sshd_config_sshervice
	Match User today
	        ForceCommand /usr/local/bin/today.sh

	Match Group _sshervice
	        PasswordAuthentication yes
	        PermitEmptyPasswords yes
	        DisableForwarding yes
	        ForceCommand /sbin/nologin
	        MaxSessions 5
	EOF
	# echo 'Include sshd_config_sshervice' >>/etc/ssh/sshd_config
	# rcctl restart sshd


3. Final result
---------------

	$ ssh today@cooldomain.tld
	Tuesday !


4. Going further
----------------

From there, it's all a matter of providing cool and/or useful services, 
so you'll have to improve what's running as the "ForceCommand" of your 
user.

Here are a few tips, in no particular order:

---  

Read login.conf(5) and sshd_config(5). Really, do it.

---  

Remember that you're giving strangers the ability to run programs on
your server. Take extra care to not provide them the ability to get
access to a shell. For example:

	#!/bin/sh
	date "$1"

This looks harmless, but passing it "-f/dev/passwd" would yield its
full content. So take extra care with the commands you allow !

---  

Worth mentionning is that you can chroot(8) your service over ssh with 
the following line under the "Match" block of sshd_config(5):

	ChrootDirectory /var/sshervice

This require to setup a proper chroot for your service to run the
program correctly.

--- 

Never trust user input.

---  

use environment variable `$SSH_ORIGINAL_COMMAND` to allow users to
specify commands. Given the following script:

	#!/bin/sh
	date -- "+${SSH_ORIGINAL_COMMAND:-%A !}"

You can now specify the date format on the command line:

	$ ssh today@cooldomain.tld
	Tuesday !
	$ ssh today@cooldomain.tld %Y-%m-%d
	2022-08-23

---  

Prefer self-contained programs over scripts.
Ideally statically link and chroot them.

--- 

If your program requires a TTY to run (like a pager for example), don't
forget to pass `-t` when you specify a command over ssh, because it does
not allocate a pseudo tty by default when passing arguments.

Imagine an online man page service:

	#!/bin/sh
	man "${SSH_ORIGINAL_COMMAND:-man}"

Make sure to add -t to force a pseudo TTY allocation for the pager to 
work:

	$ ssh -t man@cooldomain.tld sshd_config

20220823.1726]]>

               


               

               gopher://phlog.z3bra.org/0/the-gophirst-approach.txt

               

               2020-09-13T16:47:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/tls-sending-guarantee-posteo.de.txt

               

               2020-10-20T20:31:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/trip-to-reunion-island.txt

               

               2020-10-14T19:34:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/using-dns-to-bypass-hotspot-wifi.txt

               

               2020-09-26T13:42:00+02:00

               wgs

               

               


               

               gopher://phlog.z3bra.org/0/vis-vim-improved-on-steroids.txt

               

               2023-07-07T01:15:00+02:00

               wgs

                7) {
		foo = do_stuff(foo)
	}
	return foo;

Now assume we want to change a few things:

0. rename "foo" to "bar"
1. remove the useless "= 0"
2. add the missing ; on line 4

How would we do these with Vim commands ?

0. :%s/foo/bar/g
1. :1s/ = 0// (or "ggt=dt;")
2. :4s/$/;/ (or "4GA;")

Do you notice the pattern ? Even though Vim has :change, :delete and
:append/:insert commands, we used :substitute for all of them!  Think
about it the next time you use Vim. The substitute command is used 90%
of the time when using commands.

Here's how you'd do it with Sam now:

0. x/foo/ c/bar/
1. 1x/ = 0/ d
2. 4x/$/ a/;/

The x command eXtracts the selected text and runs a command on it, for
each selection separately. This is a very powerful concept, as it lets
you manipulate the text as a whole, rather than only interacting with
it one line at a time. The sam language has even more powerful features
which are described in its tutorial:

http://doc.cat-v.org/bell_labs/sam_lang_tutorial/sam_tut.pdf

Unfortunately for me, and even though Sam has a very powerful command
language, navigating the file is done exclusively with the mouse. And
I could just not give up on the muscle memory I built over all these
years of using Vim.


So what were my options ? Going back to Vim, after seing the greener
side of the grass ? Give up on Vim, and the power of modal editing ?

Vis
===

There was a third option of course: Vis !

When I first found about it, vis was a small project seeking to provide
"90% of the features of Vim, in 10% of the code". This was immediately
appealing to me, and I immediately tried it. It had rough edges, and I
missed a few features, but it was clean and fast.

Then the project became more mature, and a new feature appeared: The
Sam language was implemented into it. I was thrilled!

Vis combines the strength of both Vim and Sam into what I believe is
the ultimate text editor. Selections (or DOT) benefits from Vim "visual"
mode, allowing one to edit different portions of the file at the same
time, with multiple cursors.

And to put the icing on the cake, you can write plugins for it using 
Lua.

Whether you're a plan9 fan looking for a good Sam implementation, or an
avid Vim user, I urge you to try it, and embrace the other side of the
text editing that you're going to learn.

Acme
====

Of course, I could not end this post without talking about Acme[3], 
which I believe is the next step of editing evolution. I'm however too
scared to really commit to it, and buy a 3 buttons mouse for this sole
purpose (but I know I will, someday).

However, there is a middleground: Edit[4]! This project has not been
updated in a long time, but looks like a marvelous concept that I would
like to explore in the future.

Maybe the next (last?) step is Vim + Sam + Acme ?
-- 
~wgs

[0]: https://github.com/martanne/vis
[1]: https://blog.sanctum.geek.nz/category/vim
[2]: http://glenda.cat-v.org
[3]: http://acme.cat-v.org
[4]: https://c9x.me/edit

20230707.0115]]>

               


               

               gopher://phlog.z3bra.org/0/write-code-on-a-phone.txt

               

               2020-09-14T16:11:00+02:00

               wgs