Linode unresponsive, brute force attack?

Hi guys,

Recently my linode got unresponsive, I couldn't ssh/ping the linode at all. Checking the lish console I could saw that I was being flooded with constant firewall messages, being unresponsive to anything I tried to type, I mean, I couldn't type anything at all… it was just printing the messages bellow (these are the full length messages, from the dmesg command - since lish console doesn't show the full lenght):

[17709.700751] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=106.51.2.182 DST=<my-linode-ip> LEN=52 TOS=0x00 PREC=0x00 TTL=109 ID=13249 DF PROTO=TCP SPT=60794 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0
[17808.396955] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=188.166.242.119 DST=<my-linode-ip> LEN=40 TOS=0x00 PREC=0x00 TTL=238 ID=14988 PROTO=TCP SPT=61953 DPT=2011 WINDOW=1024 RES=0x00 SYN URGP=0
[17818.344859] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=113.176.95.237 DST=<my-linode-ip> LEN=52 TOS=0x08 PREC=0x40 TTL=107 ID=30809 DF PROTO=TCP SPT=55920 DPT=1433 WINDOW=8192 RES=0x00 SYN URGP=0
[17654.481595] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=74.120.14.90 DST=<my-linode-ip> LEN=44 TOS=0x00 PREC=0x20 T
TL=42 ID=1242 PROTO=TCP SPT=13278 DPT=54321 WINDOW=1024 RES=0x00 SYN URGP=0
[17692.504090] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=123.24.157.11 DST=<my-linode-ip> LEN=52 TOS=0x08 PREC=0x40 TTL=106 ID=17473 DF PROTO=TCP SPT=65100 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0
[17694.943237] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=220.247.242.7 DST=<my-linode-ip> LEN=52 TOS=0x00 PREC=0x00 TTL=112 ID=24822 DF PROTO=TCP SPT=54526 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0
[17696.225263] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=200.54.150.42 DST=<my-linode-ip> LEN=52 TOS=0x08 PREC=0x40 TTL=112 ID=40356 DF PROTO=TCP SPT=54034 DPT=445 WINDOW=65520 RES=0x00 SYN URGP=0
[17709.700751] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=106.51.2.182 DST=<my-linode-ip> LEN=52 TOS=0x00 PREC=0x00 TTL=109 ID=13249 DF PROTO=TCP SPT=60794 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0
[17720.983329] iptables denied: IN=eth0 OUT= MAC=f2:3c:92:a5:64:e0:62:3d:e6:d9:49:b0:08:00 SRC=187.147.68.27 DST=<my-linode-ip> LEN=52 TOS=0x00 PREC=0x00 TTL=116 ID=20333 DF PROTO=TCP SPT=37624 DPT=445 WINDOW=8192 RES=0x00 SYN URGP=0</my-linode-ip></my-linode-ip></my-linode-ip></my-linode-ip></my-linode-ip></my-linode-ip></my-linode-ip></my-linode-ip></my-linode-ip>

The only option I was left was to reboot the linode, which "solved" the problem.

Can anybody help me decipher what was going on here? Was I under some kind of attack? This was preventing all web traffic to my linode.

This is a CentOS 8 instances and I have fail2ban + nftables configured with all ports closed except for ssh, http and https.
The nftables rules are as follow:

table ip my_nft {
        chain INPUT {
                type filter hook input priority 0;
                # accept any localhost - loopback (lo0) - traffic and drop all traffic to 127/8 that doesn't use lo0
                iifname "lo" counter accept
                ip daddr 127.0.0.0/8 counter reject
                # Accept traffic originated from us
                ct state established,related counter accept
                ct state invalid drop
                # Allow SSH, HTTP and HTTPS connections
                tcp dport {ssh,http,https} counter accept
                # Allow ping
                icmp type echo-request counter accept
                # Log iptables denied calls
                limit rate 5/minute burst 5 packets counter log prefix "iptables denied: " level debug
                # Drop all other inbound - default deny unless explicitly allowed policy
                counter drop
        }
        chain FORWARD {
            type filter hook forward priority 0;
            # Drop all other inbound - default deny unless explicitly allowed policy
            counter drop
        }
        chain OUTPUT {
            type filter hook output priority 0;
            # Drop all other inbound - default deny unless explicitly allowed policy
            counter accept
        }
}

Any help would be very appreciated, thanks!