regex

import re RULES = ['-p tcp -m tcp --dport 22 -j NFLOG --nflog-prefix' ' "chain:oce9761cd-d:3;p=udp;m=udp;sport=67;dport=68"', '-p tcp -m tcp --dport 22 -j NFLOG --nflog-prefix' ' "chain:oce9761cd-d:5;m=state;state=INVALID"', '-p tcp -m tcp --dport 23 -j NFLOG --nflog-prefix' ' "chain:oce9761cd-d:3;p=udp;m=udp;sport=67;dport=68"', '-p tcp -m tcp --dport 5 -j NFLOG --nflog-prefix' ' "chain:o76a43350-9:5;m=state;state=INVALID"'] def main(): for r in RULES: m = re.search('(chain:.*?:)\d+', r) replaced = re.sub(m.group(0), m.group(1)+'%s' % 777, r) if __name__ == '__main__': main()