In this second Tor article, I will present an interesting Tor feature named hidden service. The principle of this hidden service is to make available a network service from anywhere, with only prerequisites that the computer must be powered on, tor not blocked and it has network access.

This service will be available through an address not disclosing anything about the server internet provider or its IP, instead, a hostname ending by .onion will be provided by tor for connecting. This hidden service will be only accessible through Tor.

There are a few advantages of using hidden services:

• privacy, hostname doesn’t contain any hint
• security, secure access to a remote service not using SSL/TLS
• no need for running some kind of dynamic dns updater

The drawback is that it’s quite slow and it only work for TCP services.

From here, we assume that Tor is installed and working.

Running an hidden service require to modify the Tor daemon configuration file, located in /etc/tor/torrc on OpenBSD.

Add the following lines in the configuration file to enable a hidden service for SSH:

HiddenServiceDir /var/tor/ssh_service
HiddenServicePort 22 127.0.0.1:22

The directory /var/tor/ssh_service will be be created. The directory /var/tor is owned by user _tor and not readable by other users. The hidden service directory can be named as you want, but it should be owned by user _tor with restricted permissions. Tor daemon will take care at creating the directory with correct permissions once you reload it.

Now you can reload the tor daemon to make the hidden service available.

$ doas rcctl reload tor

In the /var/tor/ssh_service directory, two files are created. What we want is the content of the file hostname which contains the hostname to reach our hidden service.

$ doas cat /var/tor/ssh_service/hostname
piosdnzecmbijclc.onion

Now, we can use the following command to connect to the hidden service from anywhere.

$ torsocks ssh piosdnzecmbijclc.onion

In Tor network, this feature doesn’t use an exit node. Hidden services can be used for various services like http, imap, ssh, gopher etc…

Using hidden service isn’t illegal nor it makes the computer to relay tor network, as previously, just check if you can use Tor on your network.

Note: it is possible to have a version 3 .onion address which will prevent hostname collapsing, but this produce very long hostnames. This can be done like in the following example:

HiddenServiceDir /var/tor/ssh_service
HiddenServicePort 22 127.0.0.1:22
HiddenServiceVersion 3

This will produce a really long hostname like tgoyfyp023zikceql5njds65ryzvwei5xvzyeubu2i6am5r5uzxfscad.onion

If you want to have the short and long hostnames, you need to specify twice the hidden service, with differents folders.

Take care, if you run a ssh service on your website and using this same ssh daemon on the hidden service, the host keys will be the same, implying that someone could theoricaly associate both and know that this public IP runs this hidden service, breaking anonymity.

Tor is a network service allowing to hide your traffic. People sniffing your network will not be able to know what server you reach and people on the remote side (like the administrator of a web service) will not know where you are from. Tor helps keeping your anonymity and privacy.

To make it quick, tor make use of an entry point that you reach directly, then servers acting as relay not able to decrypt the data relayed, and up to an exit node which will do the real request for you, and the network response will do the opposite way.

You can find more details on the Tor project homepage.

Installing tor is really easy on OpenBSD. We need to install it, and start its daemon. The daemon will listen by default on localhost on port 9050. On others systems, it may be quite similar, install the tor package and enable the daemon if not enabled by default.

# pkg_add tor
# rcctl enable tor
# rcctl start tor

Now, you can use your favorite program, look at the proxy settings and choose “SOCKS” proxy, v5 if possible (it manage the DNS queries) and use the default address: 127.0.0.1 with port 9050.

If you need to use tor with a program that doesn’t support setting a SOCKS proxy, it’s still possible to use torsocks to wrap it, that will work with most programs. It is very easy to use.

# pkg_add torsocks
$ torsocks ssh remoteserver

This will make ssh going through tor network.

Using tor won’t make you relaying anything, and is legal in most countries. Tor is like a VPN, some countries has laws about VPN, check for your country laws if you plan to use tor. Also, note that using tor may be forbidden in some networks (companies, schools etc..) because this allows to escape filtering which may be against some kind of “Agreement usage” of the network.

I will cover later the relaying part, which can lead to legal uncertainty.

Note: as torsocks is a bit of a hack, because it uses LD_PRELOAD to wrap network system calls, there is a way to do it more cleanly with ssh (or any program supporting a custom command for initialize the connection) using netcat.

ssh -o ProxyCommand='/usr/bin/nc -X 5 -x 127.0.0.1:9050 %h %p' address.onion

This can be simplified by adding the following lines to your ~/.ssh/config file, in order to automatically use the proxy command when you connect to a .onion hostname:

Host *.onion
ProxyCommand='/usr/bin/nc -X 5 -x 127.0.0.1:9050 %h %p'

This netcat command is tested under OpenBSD, there are differents netcat implementations, the flags may be differents or may not even exist.

The default OpenBSD partition layout uses a pre-defined template. If you have a disk more than 356 GB you will have unused space with the default layout (346 GB before 6.4).

It’s possible to create a new partition to use that space if you did not modify the default layout at installation. You only need to start disklabel with flag -E* and type a to add a partition, default will use all remaining space for the partition.

# disklabel -E sd0
Label editor (enter '?' for help at any prompt)
> a
partition: [m]
offset: [741349952]
size: [258863586]
FS type: [4.2BSD]
> w
> q
No label changes.

The new partition here is m. We can format it with:

# newfs /dev/rsd0m

Then, you should add it to your /etc/fstab, for that, use the same uuid as for other partitions, it would look something like 52fdd1ce48744600

52fdd1ce48744600.e /data ffs rw,nodev,nosuid 1 2

It will be auto mounted at boot, you only need to create the folder /data. Now you can do

# mkdir /data
# mount /data

and /data is usable right now.

You can read disklabel(8) and newfs for more informations.

Simple command line to display your installed packages listed by size from smallest to biggest.

pkg_info -sa | paste - - - - | sort -n -k 5

Thanks to sthen@ for the command, I was previously using one involving awk which was less readable. paste is often forgotten, it has very specifics uses which can’t be mimic easily with other tools, its purpose is to joins multiples lines into one with some specific rules.

You can easily modify the output to convert the size from bytes to megabytes with awk:

pkg_info -sa | paste - - - - | sort -n -k 5 | awk '{ NF=$NF/1024/1024 ; print }'

This divides the last element (using space separator) of each line twice by 1024 and displays the line.

Following a discussion on the OpenBSD mailing list misc, today I will write about how to manage the priority (as in nice priority) of your daemons or services.

In man page rc(8), one can read:

Before init(8) starts rc, it sets the process priority, umask, and
resource limits according to the “daemon” login class as described in
login.conf(5).  It then starts rc and attempts to execute the sequence of
commands therein.

Using /etc/login.conf we can manage some limits for services and daemon, using their rc script name.

For example, to make jenkins at lowest priority (so it doesn’t make troubles if it builds), using this line will set it to nice 20.

jenkins:priority=20

If you have a file /etc/login.conf.db you have to update it from /etc/login.conf using the software cap_mkdb. This creates a hashed database for faster information retrieval when this file is big. By default, that file doesn’t exist and you don’t have to run cap_mkdb. See login.conf(5) for more informations.

In this article I will show how to configure OpenSMTPD, the default mail server on OpenBSD, to relay mail sent locally to your smtp server. In pratice, this allows to send mail through “localhost” by the right relay, so it makes also possible to send mail even if your computer isn’t connected to the internet. Once connected, opensmtpd will send the mails.

All you need to understand the configuration and write your own one is in the man page smtpd.conf(5). This is only a highlight on was it possible and how to achieve it.

In OpenBSD 6.4 release, the configuration of opensmtpd changed drasticaly, now you have to defines rules and action to do when a mail match the rules, and you have to define those actions.

In the following example, we will see two kinds of relay, the first is through smtp over the Internet, it’s the most likely you will want to setup. And the other one is how to relay to a remote server not allowing relaying from outside.

/etc/mail/smtpd.conf

table aliases file:/etc/mail/aliases
table secrets file:/etc/mail/secrets
listen on lo0

action "local" mbox alias <aliases>
action "relay" relay
action "myserver" relay host smtps://myrelay@perso.pw auth <secrets>
action "openbsd"  relay host localhost:2525

match mail-from "@perso.pw"    for any action "myserver"
match mail-from "@openbsd.org" for any action "openbsd"
match for local action "local"
match for any action "relay"

I defined 2 actions, one from “myserver”, it has a label “myrelay” and we use auth <secrets> to tell opensmtpd it needs authentication.

The other action is “openbsd”, it will only relay to localhost on port 2525.

To use them, I define 2 matching rules of the very same kind. If the mail that I want to send match the @domain-name, then choose relay “myserver” or “openbsd”.

The “openbsd” relay is only available when I create a SSH tunnel, binding the local port 25 of the remote server to my port 2525, with flags -L 2525:127.0.0.1:25.

For a relay using authentication, the login and passwords must be defined in the file /etc/mail/secrets like this: myrelay login:Pa$$W0rd

smtpd.conf(5) explains creation of /etc/mail/secrets like this:

touch /etc/mail/secrets
chmod 640 /etc/mail/secrets
chown root:_smtpd /etc/mail/secrets

Now, restarts your server. Then if you need to send mails, just use “mail” command or localhost as a smtp server. Depending on your From address, a different relay will be used.

Deliveries can be checked in /var/log/maillog log file.

See mails in queue

doas smtpctl show queue

Try to deliver now

doas smtpctl schedule all

I wrote a script generating a RSS file from the content of the page https://www.openbsd.org/faq/current.html

This allow to be notified when a big change is made in -current.

The file is available at this place : https://perso.pw/openbsd-current.xml

Today I will cover a specific topic on OpenBSD networking. If you are using a laptop, you may switch from ethernet to wireless network from time to time. There is a simple way to keep the network instead of having to disconnect / reconnect everytime.

It’s possible to aggregate your wireless and ethernet devices into one trunk pseudo device in failover mode, which give ethernet the priority if connected.

To achieve this, it’s quite simple. If you have devices em0 and iwm0 create the following files.

/etc/hostname.em0

up

/etc/hostname.iwm0

join "office_network"  wpakey "mypassword"
join "my_home_network" wpakey "9charshere"
join "roaming phone"   wpakey "something"
join "Public Wifi"
up

/etc/hostname.trunk0

trunkproto failover trunkport em0 trunkport iwm0
dhcp

As you can see in the wireless device configuration we can specify multiples network to join, it is a new feature that will be available from 6.4 release.

You can enable the new configuration by running sh /etc/netstart as root.

This setup is explained in trunk(4) man page and in the OpenBSD FAQ as well.

Old article

Hello, it turned out that this article is obsolete. The security used in is not safe at all so the goal of this backup system isn’t achievable, thus it should not be used and I need another backup system.

One of the most important feature of dump for me was to keep track of the inodes numbers. A solution is to save the list of the inodes numbers and their path in a file before doing a backup. This can be achieved with the following command.

doas ncheck -f "\I \P\n" /var

If you need a backup tool, I would recommend the following:

Duplicity

It supports remote backend like ftp/sftp which is quite convenient as you don’t need any configuration on this other side. It supports compression and incremental backup. I think it has some GUI tools available.

Restic

It supports remote backend like cloud storage provider or sftp, it doesn’t require any special tool on the remote side. It supports deduplication of the files and is able to manage multiples hosts in the same repository, this mean that if you backup multiple computers, the deduplication will work across them. This is the only backup software I know allowing this (I do not count backuppc which I find really unusable).

Borg

It supports remote backend like ssh only if borg is installed on the other side. It supports compression and deduplication but it is not possible to save multiples hosts inside the same repository without doing a lot of hacks (which I won’t recommend).

Yesterday I subscribed to a VPN service from the french association Grifon (Grifon website[FR] | gopher://grifon.fr) to get an IPv6 access to the world and play with IPv6. I will not talk about the VPN service in this article, it would be pointless.

So, I have an IPv6 prefix of 48 bytes which mean I can have a lot of addresses (I did some maths and found 65536² addresses but I am not sure about this).

Now, I would like my computer connected through the VPN to let others computers in my network to have IPv6 connectivity.

On OpenBSD, this only requires a few services, if you want to provide IPv6 to Windows devices on your network, you will need one more.

First, configure IPv6 on your lan

# ifconfig em0 inet6 autoconf

that’s all, you can add a new line “inet6 autoconf” to your file /etc/hostname.if to get it at boot.

Now, we have to allow IPv6 to be routed through the differents interfaces of the router.

# sysctl net.inet6.ip6.forwarding=1

This change can be made persistent across reboot by adding net.inet6.ip6.forwarding=1 to the file /etc/sysctl.conf.

Now we have to configure the daemon rtadvd to advertise the we are routing, devices on the network should be able to get an IPv6 address from its advertisement.

The minimal configuration of /etc/rtadvd.conf is the following:

em0:\
   :addr="2a00:5414:7311::":prefixlen#48:

In this configuration file, you have to type your IPv6 prefix in the addr field, and the prefix length in prefixlen. Others attributes could provide DNS servers to use for example.

Then enable the service at boot and start it:

# rcctl enable rtadvd
# rcctl set rtadvd flags em0
# rcctl start rtadvd

Tweaking resolv.conf

By default OpenBSD will ask for IPv4 when resolving a hostname (see syslog.conf(5) for more explanations). So, you will never have IPv6 traffic until you use a software which will request explicit IPv6 connection or that the hostname is only defined with a AAAA field.

# echo "family inet6 inet" >> /etc/resolv.conf.tail

The file resolv.conf.tail is appended at the end of resolv.conf when dhclient modifies the file resolv.conf.

Microsoft Windows

If you have Windows systems on your network, they won’t get addresses from rtadvd. You will need to deploy dhcpv6 daemon.

The configuration file for what we want to achieve here is pretty simple, it consists of telling what range we want to allow on DHCPv6 and a DNS server. Create the file /etc/dhcp6s.conf:

interface em0 {
    address-pool pool1 3600;
};
pool pool1 {
    range 2a00:5414:7311:1111::1000 to 2a00:5414:7311:1111::4000;
};
option domain-name-servers 2001:db8::35;

Note that I added “1111” into the range because it should not be on the same network than the router.

Now, you have to install and configure the service:

# pkg_add wide-dhcpv6
# echo SOME_RANDOM_CHARACTERS | openssl enc -base64 > /etc/dhcp6sctlkey
# chmod 400 /etc/dhcp6sctlkey
# echo "dhcp6s -c /etc/dhcp6s.conf  em0" >> /etc/rc.local

The openbsd package wide-dhcpv6 doesn’t provide a rc file to start/stop the service so it must be started from a command line, a way to do it is to type the command in /etc/rc.local which is run at boot. The openssl part is mandatory for dhcpv6 to start, it requires a base64 string as a secret key in the file /etc/dhcp6sctlkey.

This article will explain quickly how to bind a folder to access it from another path. It can be useful to give access to a specific folder from a chroot without moving or duplicating the data into the chroot.

Real world example: “I want to be able to access my 100GB folder /home/my_data/ from my httpd web server chrooted in /var/www/”.

The trick on OpenBSD is to use NFS on localhost. It’s pretty simple.

# rcctl enable portmap nfsd mountd
# echo "/home/my_data -network=127.0.0.0 -mask=255.255.255.0" > /etc/exports
# rcctl start portmap nfsd mountd

The order is really important. You can check that the folder is available through NFS with the following command:

$ showmount -e
Exports list on localhost:
/home/my_data               loopback

If you don’t have any line after “Exports list on localhost:”, you should kill mountd with pkill -9 mountd and start mountd again. I experienced it twice when starting all the daemons from the same commands but I’m not able to reproduce it. By the way, mountd only supports reload.

If you modify /etc/exports, you only need to reload mountd using rcctl reload mountd.

Once you have check that everything was alright, you can mount the exported folder on another folder with the command:

# mount localhost:/home/my_data /var/www/htdocs/my_data

You can add -ro parameter in the /etc/exports file on the export line if you want it to be read-only where you mount it.

Note: On FreeBSD/DragonflyBSD, you can use mount_nullfs /from /to, there is no need to setup a local NFS server. And on Linux you can use mount --bind /from /to and some others ways that I won’t cover here.

If you have enough memory on your system and that you can afford to use a few hundred megabytes to store temporary files, you may want to mount a mfs filesystem on /tmp. That will help saving your SSD drive, and if you use an old hard drive or a memory stick, that will reduce your disk load and improve performances. You may also want to mount a ramdisk on others mount points like ~/.cache/ or a database for some reason, but I will just explain how to achieve this for /tmp with is a very common use case.

First, you may have heard about tmpfs, but it has been disabled in OpenBSD years ago because it wasn’t stable enough and nobody fixed it. So, OpenBSD has a special filesystem named mfs, which is a FFS filesystem on a reserved memory space. When you mount a mfs filesystem, the size of the partition is reserved and can’t be used for anything else (tmpfs, as the same on Linux, doesn’t reserve the memory).

Add the following line in /etc/fstab (following fstab(5)):

swap /tmp mfs rw,nodev,nosuid,-s=300m 0 0

The permissions of the mountpoint /tmp should be fixed before mounting it, meaning that the ==/tmp== folder on ==/== partition should be changed to 1777:

# umount /tmp
# chmod 1777 /tmp
# mount /tmp

This is required because mount_mfs inherits permissions from the mountpoint.

Frequently asked questions (with answers) on #openbsd IRC channel

Please read the official OpenBSD FAQ

I am writing this to answer questions asked too many times. If some answers get good enough, maybe we could try to merge it in the OpenBSD FAQ if the topic isn’t covered. If the topic is covered, then a link to the official FAQ should be used.

If you want to participate, you can fetch the page using gopher protocol and send me a diff:

$ printf '/~solene/article-openbsd-faq.txt\r\n' | nc dataswamp.org 70 > faq.md

OpenBSD features / not features

Here is a list for newcomers to tell what is and what is not OpenBSD

See OpenBSD Innovations

• Packet Filter : super awesome firewall

• Sane defaults : you install, it works, no tweak

• Stability : upgrades go smooth and are easy

• pledge and unveil : security features to reduce privileges of software, lots of ports are patched

• W^X security

• Has only FFS file system which is slow and has no “feature”

• No wine for windows compatibility

• No linux compatibility

• No bluetooth support

• No usb3 full speed performance

• No VM guest additions

• Only in-house VMM for being a VM host, only supports OpenBSD and some Linux

• Poor fuse support (it crashes quite often)

• No nvidia support (nvidia’s fault)

• No container / docker / jails

Does OpenBSD has a Code Of Conduct?

No and there is no known plan of having one.

This is a topic upsetting OpenBSD people, just don’t ask about it and send patches.

What is the OpenBSD release process?

OpenBSD FAQ official information

The last two releases are called “-release” and are officially supported (patches for security issues are provided).

-stable version is the latest release with the base system patches applied, the -stable ports tree has some patches backported from -current, mainly to fix security issues. Official packages are not built for -stable. You have to build them yourself or install them using a third party service like M:Tier

What is -current?

It’s the development version with latest packages and latest code. You shouldn’t use it only to get latest package versions.

How do I install -current ?

OpenBSD FAQ about current

• download the latest snapshot install .iso or .fs file from your favorite mirror under /snapshots/ directory
• boot from it

How do I upgrade to -current

OpenBSD FAQ about current

• download the latest bsd.rd file from your favorite mirror
• verify its checksum and signature using signify and SHA256.sig file
• rename the old ramdisk kernel as /bsd.rd.old just in case
• copy the ramdisk kernel in its place - /bsd.rd
• reboot
• type “boot bsd.rd” at bootloader prompt
• choose “U” to upgrade
• reboot after the upgrade process
• pkg_add -u to update your packages

Repeat in order to upgrade to a newer -current snapshot

How do I update packages on my release version ?

Packages are frozen at the release and not updated.

When you fetch OpenBSD src or ports from CVS and that you want to save bandwidth during the process there is a little trick that change everything: compression

Just add -z9 to the parameter of your cvs command line and the remote server will send you compressed files, saving 10 times the bandwidth, or speeding up 10 times the transfer, or both (I’m in the case where I have differents users on my network and I’m limiting my incoming bandwidth so other people can have bandwidth too so it is important to reduce the packets transffered if possible).

The command line should looks like:

$ cvs -z9 -qd anoncvs@anoncvs.fr.openbsd.org:/cvs checkout -P src

Today I will explain how to do traffic limit with OpenBSD and PF. This is not hard at all if you want something easy, the man page pf.conf(5) in QUEUEING section is pretty good but it may disturbing when you don’t understand how it works. This is not something I master, I’m not sure of the behaviour in some cases but the following example works as I tested it ! :)

Use case

Internet is down at home, I want to use my phone as 4G router trough my OpenBSD laptop which will act as router. I don’t want the quota (some Gb) to be eaten in a few seconds, this connection allow to download up to 10 Mb/s so it can go quickly !

We will limit the total bandwidth to 1M (~ 110 kb/s) for people behind the NAT. It will be slow, but we will be sure that nothing behind the NAT like a program updating, cloud stuff synchronizing or videos in auto play won’t consume our quota.

Edit /etc/pf.conf accordigly to your network

internet="urndis0"
lan="em0"

# we define our available bandwidth
queue main on $lan bandwidth 100M

# we will let 1M but we will allow
# 3M during 200 ms when initiating connection to keep the web a bit interactive
queue limited parent main bandwidth 1M min 0K max 1M burst 3M for 200ms default

set skip on lo

# we do NAT here
match out on egress inet from !(egress:network) to any nat-to (egress:0)

block all
pass out quick inet

# we apply the queue here on EVERYTHING coming from the internet
pass in on $lan set queue limited

This ONLY defines queue for DOWNLOADING, you can only set the queue on the lan interface, this won’t work on egress (network interface having internet) because you can’t limit what go in your interface, it’s already there when you want to limit.

Per protocol ?

You can define queues per remote port by creating new queues and doing something like this:

pass in on $lan proto tcp port ssh set queue ssh
pass in on $lan proto tcp port www set queue web

Per host ?

As before, you can apply queues on IP host/range rather than protocols, or you can even mix both if you want.

Warning

The limit function changed in OpenBSD 5.5, everything you can read on the internet about ALTQ isn’t working anymore.

Today OpenBSD 6.1 has been released, I won’t copy & paste the change list but, in a few words, it gets better.

Link to the official announce

I already upgraded a few servers, with both methods. One with bsd.rd upgrade but that requires physical access to the server and the other method well explained in the upgrade guide which requires to untar the files and do move some files. I recommend using bsd.rd if possible.

Hello,

I have a pfsense appliance (Netgate 2440) with a usb console port, while it used to be a serial port, now devices seems to have a usb one. If you plug an usb wire from an openbsd box to it, you woull see this in your dmesg

uslcom0 at uhub0 port 5 configuration 1 interface 0 "Silicon Labs CP2104 USB to UART Bridge Controller" rev 2.00/1.00 addr 7
ucom0 at uslcom0 portno 0

To connect to it from OpenBSD, use the following command:

# cu -l /dev/cuaU0 -s 115200

And you’re done

Let’s encrypt is a free service which provides free SSL certificates. It is fully automated and there are a few tools to generate your certificates with it. In the following lines, I will just explain how to get a certificate in a few minutes. You can find more informations on Let’s Encrypt website.

To make it simple, the tool we will use will generate some keys on the computer, send a request to Let’s Encrypt service which will use http challenging (there are also dns and another one kind of challenging) to see if you really own the domain for which you want the certificate. If the challenge process is ok, you have the certificate.

Please, if you don’t understand the following commands, don’t type it.

While the following is right for OpenBSD, it may change slightly for others systems. Acme-client is part of the base system, you can read the man page acme-client(1).

Prepare your http server

For each certificate you will ask a certificate, you will be challenged for each domain on the port 80. A file must be available in a path under “/.well-known/acme-challenge/”.

You must have this in your httpd config file. If you use another web server, you need to adapt.

server "mydomain.com" {
    root "/empty"
    listen on * port 80
    location "/.well-known/acme-challenge/*" {
        root { "/acme/" , strip 2 }
    }
}

The “strip 2” part is IMPORTANT. (I’ve lost 45 minutes figuring out why root “/acme/” wasn’t working.)

Prepare the folders

As stated in acme-client man page and if you don’t need to change the path. You can do the following commands with root privileges :

# mkdir /var/www/acme
# mkdir -p /etc/ssl/acme/private /etc/acme
# chmod 0700 /etc/ssl/acme/private /etc/acme

Request the certificates

As root, in the acme-client sources folder, type the following the generate the certificates. The verbose flag is interesting and you will see if the challenging step work. If it doesn’t work, you should try manually to get a file like with the same path tried from Let’s encrypt, and try again the command when you succeed.

$ acme-client -vNn mydomain.com www.mydomain.com mail.mydomain.com

Use the certificates

Now, you can use your SSL certificates for your mail server, imap server, ftp server, http server…. There is a little drawback, if you generate certificates for a lot of domains, they are all written in the certificate. This implies that if someone visit one page, look at the certificate, this person will know every domain you have under SSL. I think that it’s possible to ask every certificate independently but you will have to play with acme-client flags and make some kind of scripts to automatize this.

Certificate file is located at /etc/ssl/acme/fullchain.pem and contains the full certification chain (as its name is explicit). And the private key is located at /etc/ssl/acme/private/privkey.pem.

Restart the service with the certificate.

Renew certificates

Certificates are valid for 3 months. Just type

./acme-client mydomain.com www.mydomain.com mail.mydomain.com

Restart your ssl services

EASY !

I am using the following lines in my /etc/sysctl.conf file, this boosted the performance on my multiples OpenBSD desktop:

kern.maxvnodes=768000
kern.maxfiles=32768
kern.maxclusters=256000
kern.seminfo.semmni=1024
kern.seminfo.semmns=4096
kern.shminfo.shmmax=805306368
kern.bufcachepercent=90