If you have any machine with an SSH server open to the world and you take a look at your logs, you may be alarmed to see so many login attempts from so many unknown IP addresses. DenyHosts is a pretty neat service for Unix-based systems which works in the background reviewing such logs and appending the offending addresses into the hosts.deny file, thus avoiding brute-force attacks.

The following R snippet may be useful to quickly visualise a hosts.deny file with logs from DenyHosts. Such file may have comments (lines starting with #), and actual records are stored in the form <service>: <IP>. Therefore, read.table is more than enough to load it into R. The rgeolocate package is used to geolocate the IPs, and the counts per country are represented in a world map using rworldmap:

library(dplyr)
library(rgeolocate)
library(rworldmap)
hosts.deny <- "/etc/hosts.deny"
db <- system.file("extdata", "GeoLite2-Country.mmdb", package="rgeolocate")
read.table(hosts.deny, col.names=c("service", "IP")) %>%
  pull(IP) %>%
  maxmind(db, fields="country_code") %>%
  count(country_code) %>%
  as.data.frame() %>%
  joinCountryData2Map(joinCode="ISO2", nameJoinColumn="country_code") %>%
  mapCountryData(nameColumnToPlot="n", catMethod="pretty", mapTitle="Attacks per country")
## 74 codes from your data successfully matched countries in the map
## 2 codes from your data failed to match with a country code in the map
## 168 codes from the map weren't represented in your data

Then, you may consider more specific access restrictions based on IP prefixes…