According to jail.conf we actually need to separate multiple values
with spaces instead of commas. On some versions of fail2ban this is
a fatal error:
> CRITICAL Unhandled exception in Fail2Ban:
> Traceback (most recent call last):
> File "/usr/lib/python3/dist-packages/fail2ban/server/jailthread.py", line 66, in run_with_except_hook
> run(*args, **kwargs)
> File "/usr/lib/python3/dist-packages/fail2ban/server/filtersystemd.py", line 246, in run
> *self.formatJournalEntry(logentry))
> File "/usr/lib/python3/dist-packages/fail2ban/server/filter.py", line 432, in processLineAndAdd
> if self.inIgnoreIPList(ip, log_ignore=True):
> File "/usr/lib/python3/dist-packages/fail2ban/server/filter.py", line 371, in inIgnoreIPList
> "(?<=b)1+", bin(DNSUtils.addr2bin(s[1]))).group())
> File "/usr/lib/python3/dist-packages/fail2ban/server/filter.py", line 928, in addr2bin
> return struct.unpack("!L", socket.inet_aton(ipstring))[0]
> OSError: illegal IP address string passed to inet_aton
This affects (at least) fail2ban 0.9.3 on Ubuntu 16.04, but I never
noticed.
Some hosts can use fail2ban's nginx-botsearch filter to ban anyone
making requests to non-existent files like wp-login.php. There is
no reason to request such files naively and anyone found doing so
can be banned immediately.
In theory I should report them to AbuseIPDB.com, but that will take
a little more wiring up.
For now I am still manually updating this, as we can only hit their
API five times per day, so it is not possible to have each host get
the list themselves every day with our one API key.
This adds Abuse.sh's list of IPs using blacklisted SSL certificates
to nftables. These IPs are high confidence indicators of compromise
and we should not route them. The list is updated daily by a systemd
timer.
See: https://sslbl.abuse.ch/blacklist/
We should only try to start the nftables service after we finish
copying all the config files just in case there is some unclean
state in one of them. On a first run this shouldn't matter, but
after nftables and some abuse list update scripts have run this
can happen (mostly in testing!).
cron-apt updates the system against the security-only databases at
night so many packages are "missing" unless you run apt update. We
need to update the cache on all apt tasks actually because I might
be running them by their tag and they currently only get updated at
the beginning of the playbook.
This opens TCP port 22 on all hosts, TCP ports 80 and 443 on hosts
in the web group, and allows configuration of "extra" rules in the
host or group vars.
I will try using nftables directly instead of via firewalld as of
Debian 11 as it is the replacement for the iptables/ipset stack in
recent years and is easier to work with.
This also includes a systemd service, timer, and script to update
the spamhaus DROP lists as nftables sets.
Still need to add fail2ban support.
Recommended by ssh-audit, but also generally the concensus for a few
years that Encrypt-and-MAC is hard to get right. OpenSSH has several
Encrypt-then-MAC schemes available so we can use those.
See: https://www.daemonology.net/blog/2009-06-24-encrypt-then-mac.html
This was to enable the persistent systemd journal, but it is no lo-
nger needed as of Ubuntu 18.04 and Debian 11. I had removed the ta-
asks long ago, but forgot to remove this file.
This configures the recommended DROP, EDROP, and DROPv6 lists from
Spamhaus as ipsets in firewalld. First we copy an empty placeholder
ipset to seed firewalld, then we use a shell script to download the
real lists and activate them. The same shell script is run daily as
a service (update-spamhaus-lists.service) by a systemd timer.
I am strictly avoiding any direct ipset commands here because I want
to make sure that this works on older hosts where ipsets is used as
well as newer hosts that have moved to nftables such as Ubuntu 20.04.
So far I have tested this on Ubuntu 16.04, 18.04, and 20.04, but ev-
entually I need to abstract the tasks and run them on CentOS 7+ as
well.
See: https://www.spamhaus.org/drop/
This comes from the AbuseIPDB with a confidence level of 95%. I use
the following command to download and sort the IPs:
$ curl -G https://api.abuseipdb.com/api/v2/blacklist -d \
confidenceMinimum=95 -H "Key: $ABUSEIPDB_API_KEY" \
-H "Accept: text/plain" | sort | sed -e '/:/w /tmp/ipv6.txt' \
-e '/:/d' > /tmp/ipv4.txt
I manually add the XML formatting to each file and run them through
tidy:
$ tidy -xml -utf8 -m -iq -w 0 roles/common/files/abusers-ipv4.xml
$ tidy -xml -utf8 -m -iq -w 0 roles/common/files/abusers-ipv6.xml
Instead of manually creating our own self-signed certificate we can
use the one created automatically by the ssl-cert package on Debian.
This is only used by the dummy default HTTPS vhost.
