import re
 
pattern = r"Routing for Networks:\n((?:(?:\d{1,3}\.){3}\d{1,3}/\d+\n)+)(?=Routing)"
 
s = ("Routing for Networks:\n"
            "0.0.0.0/32\n"
            "5.6.4.3/24\n"
            "2.3.1.4/32\n"
            "Routing Information Sources:\n"
            "Gateway         Distance      Last Update\n"
            "192.168.61.100        90      00:33:51\n"
            "192.168.61.103        90      00:33:43")
 
m = re.search(pattern, s)
if m:
    print([s for s in m.group(1).split("\n") if s])

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