Regex are useful to cope with basic unix / linux administration tasks.
To extract IP from file, this simple command do the trick :
grep -o '[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}\.[0-9]\{1,3\}' /var/log/auth.log 15-08-27 - 16:17:00
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
188.216.199.96
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142
11.213.54.142

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