[knock] can't parse filter expression: syntax error
I upgraded from Alpine v3.8 to v3.10 and knock does not work with the same knockd.conf config. On v3.10 (which uses knock v0.8-r1), the same config file that previously worked under knock v0.7-r2 results in a syntax error. I ran "knockd --debug --verbose" on both the working Alpine v3.8 and Alpine v3.10 that does not work. It appears that the difference in the pcap expression is an extra "( )" around "dst host 192.168.1.10".
WORKS: Alpine 3.8 / Knock 0.7-r2
Adding pcap expression for door 'openclose': (dst host 192.168.1.10 and (((tcp dst port 2500) and tcp[tcpflags] & tcp-syn != 0)))
DOES NOT WORK: Alpine 3.10 / Knock 0.8-r1
Adding pcap expression for door 'openclose': ((dst host 192.168.1.10) and (((tcp dst port 2500) and tcp[tcpflags] & tcp-syn != 0)))
pcap_compile: can't parse filter expression: syntax error
Any one else with this issue? Should we downgrade until fixed upstream? Not sure if this could also be impacted by the libpcap version between Alpine 3.8 vs 3.10.