Hi Dave, I found the problem. The last decoder in kernel-iptables_apparmor_decoders.xml doesn't have a prematch tag. I fixed it here <https://github.com/wazuh/ossec-rules/commit/48db55be1917596f9de69a0d7e5efabe8d1dadd0>, just add that line. Usually, every decoder should have a prematch because when OSSEC matches a decoder just with regex it doesn't continue looking for the next decoder.
Now, you can place your decoder in local_decoders and it will work. I recommend you use prematch in your decoder too. <decoder name="local_iptables"> <parent>iptables</parent> <prematch>^[\s*\d+.\d+] ipt:</prematch> <regex offset="after_prematch">(\S+): in=\.+ src=(\S+) dst=(\S+) </regex> <order>action,srcip,srcdst</order> </decoder> **Phase 1: Completed pre-decoding. full event: 'May 21 07:06:25 agora kernel: [ 303.966106] IPT: GEOIP VIETNAM DROP: IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=116.110.88.148 DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 ID=11844 DF PROTO=TCP SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0' hostname: 'agora' program_name: 'kernel' log: '[ 303.966106] IPT: GEOIP VIETNAM DROP: IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=116.110.88.148 DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 ID=11844 DF PROTO=TCP SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0' **Phase 2: Completed decoding. decoder: 'iptables' action: 'DROP' srcip: '116.110.88.148' srcdst: '192.168.0.3' Regards, Jesus Linares. On Saturday, May 21, 2016 at 7:58:35 PM UTC+2, Dave Vehrs wrote: > > Hi all, > > I'm sure I'm overlooking something simple but I've run into a small issue > with the standard iptables decoders in > ossec_decoders/kernel-iptables_apparmor_decoders.xml > > The problem I have is that the patterns described in the various decoders > in this file do not match the pattern that I use for Iptables logs. Simple > issue, right? > > Examples of my logs: > May 21 05:56:10 agora kernel: [25811.034035] IPT: GEOIP VIETNAM DROP: > IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 > SRC=14.160.56.206 DST=192.168.0.3 LEN=52 TOS=0x08 PREC=0x20 TTL=117 > ID=21885 DF PROTO=TCP SPT=56689 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 > May 21 06:00:25 agora kernel: [26065.545901] IPT: GEOIP VIETNAM DROP: > IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 > SRC=42.114.164.226 DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=116 > ID=21576 DF PROTO=TCP SPT=59826 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 > May 21 06:12:36 agora kernel: [26796.745515] IPT: GEOIP LATVIA DROP: > IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=195.3.144.85 > DST=192.168.0.3 LEN=48 TOS=0x00 PREC=0x00 TTL=119 ID=3941 DF PROTO=TCP > SPT=62658 DPT=22 WINDOW=64240 RES=0x00 SYN URGP=0 > May 21 07:02:09 agora kernel: [ 47.395341] IPT: Stealth Scan Reject: > IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:b8:ae:ed:78:1b:20:08:00 SRC=192.168.0.55 > DST=192.168.0.3 LEN=40 TOS=0x00 PREC=0x00 TTL=64 ID=14452 DF PROTO=TCP > SPT=54776 DPT=25 SEQ=1191919764 ACK=0 WINDOW=0 RES=0x00 RST URGP=0 > > The problem with the patterns in kernel-iptables_apparmor_decoders.xml is > they commonly seem to use a single word for the Iptables log prefix or > start with "Shorewall". Neither of which work for me. > > Now, I have been able to write a decoder that works with these logs. It > is: > > <decoder name="local_iptables"> > <parent>iptables</parent> > <regex offset="after_parent">^[\s*\d+.\d+] ipt: \.+ (\S+): in=\.+ > src=(\S+) dst=(\S+) </regex> > <order>action,srcip,dstip</order> > </decoder> > > However, this only works if I place it in > ossec_decoders/kernel-iptables_apparmor_decoders.xml. If I move it to > local_decoder.xml, it appears to be never seen. > > Included in that file, the output of ossec-logtest is: > >> May 21 07:06:25 agora kernel: [ 303.966106] IPT: GEOIP VIETNAM DROP: >> IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 >> SRC=116.110.88.148 DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 >> ID=11844 DF PROTO=TCP SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 >> >> **Phase 1: Completed pre-decoding. >> full event: 'May 21 07:06:25 agora kernel: [ 303.966106] IPT: >> GEOIP VIETNAM DROP: IN=eth0 OUT= >> MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=116.110.88.148 >> DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 ID=11844 DF PROTO=TCP >> SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 ' >> hostname: 'agora' >> program_name: 'kernel' >> log: '[ 303.966106] IPT: GEOIP VIETNAM DROP: IN=eth0 OUT= >> MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=116.110.88.148 >> DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 ID=11844 DF PROTO=TCP >> SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 ' >> **Phase 2: Completed decoding. >> decoder: 'iptables' >> action: 'DROP' >> srcip: '116.110.88.148' >> dstip: '192.168.0.3' > > > However when that decoder is included in local_decoder.xml, the output of > ossec-logtest is: > >> May 21 07:06:25 agora kernel: [ 303.966106] IPT: GEOIP VIETNAM DROP: >> IN=eth0 OUT= MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 >> SRC=116.110.88.148 DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 >> ID=11844 DF PROTO=TCP SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 >> >> **Phase 1: Completed pre-decoding. >> full event: 'May 21 07:06:25 agora kernel: [ 303.966106] IPT: >> GEOIP VIETNAM DROP: IN=eth0 OUT= >> MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=116.110.88.148 >> DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 ID=11844 DF PROTO=TCP >> SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 ' >> hostname: 'agora' >> program_name: 'kernel' >> log: '[ 303.966106] IPT: GEOIP VIETNAM DROP: IN=eth0 OUT= >> MAC=54:9f:35:20:cf:e4:c8:6c:87:6d:29:00:08:00 SRC=116.110.88.148 >> DST=192.168.0.3 LEN=52 TOS=0x00 PREC=0x00 TTL=110 ID=11844 DF PROTO=TCP >> SPT=64357 DPT=22 WINDOW=8192 RES=0x00 SYN URGP=0 ' >> **Phase 2: Completed decoding. >> decoder: 'iptables' > > > So the question I have is how I can enable parent from within > local_decoders.xml? I appear to have the basic syntax right but there is > something different when it changes which file it's in. > > And I do believe it should be enabled for both cases, because in my > ossec.conf, I have three lines: > <decoder_dir>etc/ossec_decoders</decoder_dir> > <decoder_dir>etc/wazuh_decoders</decoder_dir> > <decoder>etc/local_decoder.xml</decoder> > > Any ideas? Or did I just skip part of the RTFM? > > Thanks, > > Dave > -- --- You received this message because you are subscribed to the Google Groups "ossec-list" group. To unsubscribe from this group and stop receiving emails from it, send an email to ossec-list+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.