obspy.clients.fdsn.client.Client.RE_IPv4

Client.RE_IPv4 = '(?:(?:25[0-5]|2[0-4]\\d|[0-1]?\\d{1,2})(?:\\.(?:25[0-5]|2[0-4]\\d|[0-1]?\\d{1,2})){3})'

Regex for IPv4