const regex = /\sfor\s(?:invalid\suser\s)?(?<Username>\w+)\s\w+\s(?<IP>[^\s]+)/gm;
// Alternative syntax using RegExp constructor
// const regex = new RegExp('\\sfor\\s(?:invalid\\suser\\s)?(?<Username>\\w+)\\s\\w+\\s(?<IP>[^\\s]+)', 'gm')
const str = `Thu Sep 07 2021 00:15:06 mailsv1 sshd[2605]: Failed password for invalid user itmadmin from 194.8.74.23 port 4692 ssh2
Thu Sep 07 2021 00:15:06 mailsv1 sshd[3759]: Failed password for nagios from 194.8.74.23 port 3769 ssh2`;
// Reset `lastIndex` if this regex is defined globally
// regex.lastIndex = 0;
let m;
while ((m = regex.exec(str)) !== null) {
// This is necessary to avoid infinite loops with zero-width matches
if (m.index === regex.lastIndex) {
regex.lastIndex++;
}
// The result can be accessed through the `m`-variable.
m.forEach((match, groupIndex) => {
console.log(`Found match, group ${groupIndex}: ${match}`);
});
}
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for JavaScript, please visit: https://developer.mozilla.org/en/docs/Web/JavaScript/Guide/Regular_Expressions