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()