Snort mailing list archives
Re: File preprocessor fails to capture files
From: Russ <rucombs () cisco com>
Date: Fri, 15 May 2015 09:17:40 -0400
Pablo,That's a great detailed analysis. The reordering of data segments is part of what TCP does but that applies to each side of a flow separately. It is not normal that an ACK, which travels in the opposite direction of the data it is acknowledging, is sent before the data is received, which is what the capture implies. Although this reordering is actually just an artifact of the capture, an ACK advances the window and Snort has to simply note the gap and move on. The alternative, in almost all cases, would lead to flawed reassembly and evasions.
You haven't mentioned selective ACK which could possibly be confusing Snort. Can you send a pcap of the misordered capture? If you capture this on a different (maybe higher speed) device, is the order correct?
Thanks Russ On 5/15/15 5:25 AM, Pablo Cantos Polaino wrote:
Hi Hui,I'm sorry for the delay, but I wanted to test some scenarios before replying you.Following your advice, I've disabled some optimizations in order to not to get jumbo frames, which actually were present in my PCAP file. After disabling the optimization, I was able to generate other PCAP files without Jumbo frames.This time I got several traffic network captures by using 3 small files (8.1KB, 18KB and 63KB) and 'wget' and 'tcpdump' programs. I've tried to get the captures as much simple as possible in order to avoid external "noises", and to do that I've got 6 PCAP files for every one of these three files, which gives me 18 PCAP files. I've also "cleaned" all these PCAP files by removing the rest of the sessions in which the file isn't in.After that, what I found on my first tests is that in all cases every file was not always captured by Snort (IDS mode). When a file was not captured, there were always 1 or 2 TCP Gaps and no TCP Discards and I could see with Wireshark that there were at least one packet marked as "TCP ACKed unseen segment" (see filter tcp.analysis.ack_lost_segment in Wireshark), which is due to one ACK that arrives before the Datapacket acked does. On the other hand, when the file was captured, there were neither TCP Gaps nor TCP Discards and I could check with Wireshark that there were no packet marked as "TCP ACKed unseen segment". Se examples below:Regular PCAP file: pkt 1: server | client | seq_100 | ack_050 | len 100 pkt 2: server | client | seq_200 | ack_050 | len 100 pkt 3: server | client | seq_300 | ack_050 | len 100 pkt 4: server | client | seq_400 | ack_050 | len 100 pkt 5: client | server | seq_050 | ack_200 | len 000 <- ack for pkt 1 pkt 6: client | server | seq_050 | ack_300 | len 000 <- ack for pkt 2 pkt 7: client | server | seq_050 | ack_400 | len 000 <- ack for pkt 3 pkt 8: client | server | seq_050 | ack_500 | len 000 <- ack for pkt 4 PCAP file with one TCP ACKed unseen segment: pkt 1: server | client | seq_100 | ack_050 | len 100 pkt 2: server | client | seq_200 | ack_050 | len 100 pkt 3: server | client | seq_300 | ack_050 | len 100 pkt 4: client | server | seq_050 | ack_200 | len 000 <- ack for pkt 1 pkt 5: client | server | seq_050 | ack_300 | len 000 <- ack for pkt 2 pkt 6: client | server | seq_050 | ack_400 | len 000 <- ack for pkt 3pkt 7: client | server | seq_050 | ack_500 | len 000 <- ack for pkt 8 (TCP ACKed unseen segment)pkt 8: server | client | seq_400 | ack_050 | len 100I've reordered some packets In PCAP files that cause TCP Gaps in Snort by putting ACKs after their corresponding Datapacket (in the example above it would consist in put the pkt 8 before pkt 7). This time, Snort didn't see TCP Gaps when read these reordered PCAP files and was able to capture the file inside.This packet disruption is causing Snort to not work properly, since it's finding "false" TCP Gaps, and I say "false" because actually these Datapackets exists, but their corresponding ACKs are arriving before them (just one position before is enough to discard the Datapacket).To understand better how far Snort is able to take into account packet disruptions, I've also tried to reorder a "consistent" PCAP file, with neither TCP ACKed unseen segments nor TCP Gaps or Discard in Snort and whose file inside is captured by Snort. Example of "consistent" or regular PCAP file:pkt 1: server | client | seq_100 | ack_050 | len 100 pkt 2: server | client | seq_200 | ack_050 | len 100 pkt 3: server | client | seq_300 | ack_050 | len 100 pkt 4: server | client | seq_400 | ack_050 | len 100 pkt 5: client | server | seq_050 | ack_200 | len 000 <- ack for pkt 1 pkt 6: client | server | seq_050 | ack_300 | len 000 <- ack for pkt 2 pkt 7: client | server | seq_050 | ack_400 | len 000 <- ack for pkt 3 pkt 8: client | server | seq_050 | ack_500 | len 000 <- ack for pkt 4What I've done with this PCAP file is to alter the position of two Datapacket, but without causing TCP ACKed unseen segments. See example below in which pkt 2 is moved before pkt 3:pkt 1: server | client | seq_100 | ack_050 | len 100 pkt 2: server | client | seq_300 | ack_050 | len 100 pkt 3: server | client | seq_200 | ack_050 | len 100 pkt 4: server | client | seq_400 | ack_050 | len 100 pkt 5: client | server | seq_050 | ack_200 | len 000 <- ack for pkt 1 pkt 6: client | server | seq_050 | ack_300 | len 000 <- ack for pkt 2 pkt 7: client | server | seq_050 | ack_400 | len 000 <- ack for pkt 3 pkt 8: client | server | seq_050 | ack_500 | len 000 <- ack for pkt 4In this case, Snort is able to detect this packet re-ordering and it does not affect to the final result, since there's neither TCP Gaps nor Discards and the file inside the TCP session is captured by Snort.I've replayed all these tests in IPS mode with the same result, by using 'tcpreplay' program and sending these PCAP files through a network interface.Now, my question is whether there is a way that Snort could manage the "false" TCP ACKed unseen segments due to packet re-ordering, in the same way it manages the Datapacket re-ordering. Since the packet re-ordering seems to be a common issue in networks.I've reviewed the Stream5 and Frag3 options looking for a possible configuration to solve this, but I haven't found anything related to this.If any Snort output, PCAP file or whatever were useful to you, please don't hesitate to ask for it.Best Regards and Thank you very much for your help, Pablo Cantosredborder.org <http://redborder.org> / pcantos () redborder org <mailto:pcantos () redborder org>2015-05-09 2:51 GMT+02:00 Hui Cao (huica) <huica () cisco com <mailto:huica () cisco com>>:Hi Pablo, I am pretty sure that the Jumbo frame is the issue for PCAP. They are even bigger than 60000, which is not normal. For the interface one, there are lots of discards. Not all traffic are processed by snort, therefore there are lots gaps in the TCP stream. You can try inline mode, instead of passive. Either there is some configuration issue for interface, or the speed of passive interface might be too high to be processed by your CPU. Best, Hui. From: Pablo Cantos Polaino <pcantos () redborder org <mailto:pcantos () redborder org>> Date: Friday, May 8, 2015 at 5:59 PM To: Hui Cao <huica () cisco com <mailto:huica () cisco com>> Cc: "snort-users () lists sourceforge net <mailto:snort-users () lists sourceforge net>" <snort-users () lists sourceforge net <mailto:snort-users () lists sourceforge net>> Subject: Re: [Snort-users] File preprocessor fails to capture files Hi Hui, I've replaced config paf_max: 16000 by 60000 as you propose. File type was not identified because I had disabled type_id option in preprocessor file_inspect. I've replayed the tests with paf_max = 60000 and both type_id enabled and disabled. In both cases the capture files are the same (number and size) when sniffering from an interface and reading from a PCAP file. So I'm pasting below the exit stats when type_id is enabled and paf_max = 60000: Exit stats when reading the PCAP file and type_id enabled: =============================================================================== Run time for packet processing was 3.978146 seconds Snort processed 3326 packets. Snort ran for 0 days 0 hours 0 minutes 3 seconds Pkts/sec: 1108 =============================================================================== Memory usage summary: Total non-mmapped bytes (arena): 10190848 Bytes in mapped regions (hblkhd): 122081280 Total allocated space (uordblks): 8072896 Total free space (fordblks): 2117952 Topmost releasable block (keepcost): 133008 =============================================================================== Packet I/O Totals: Received: 3326 Analyzed: 3326 (100.000%) Dropped: 0 ( 0.000%) Filtered: 0 ( 0.000%) Outstanding: 0 ( 0.000%) Injected: 0 =============================================================================== Breakdown by protocol (includes rebuilt packets): Eth: 3333 (100.000%) VLAN: 0 ( 0.000%) IP4: 3333 (100.000%) Frag: 0 ( 0.000%) ICMP: 0 ( 0.000%) UDP: 40 ( 1.200%) TCP: 3293 ( 98.800%) IP6: 0 ( 0.000%) IP6 Ext: 0 ( 0.000%) IP6 Opts: 0 ( 0.000%) Frag6: 0 ( 0.000%) ICMP6: 0 ( 0.000%) UDP6: 0 ( 0.000%) TCP6: 0 ( 0.000%) Teredo: 0 ( 0.000%) ICMP-IP: 0 ( 0.000%) IP4/IP4: 0 ( 0.000%) IP4/IP6: 0 ( 0.000%) IP6/IP4: 0 ( 0.000%) IP6/IP6: 0 ( 0.000%) GRE: 0 ( 0.000%) GRE Eth: 0 ( 0.000%) GRE VLAN: 0 ( 0.000%) GRE IP4: 0 ( 0.000%) GRE IP6: 0 ( 0.000%) GRE IP6 Ext: 0 ( 0.000%) GRE PPTP: 0 ( 0.000%) GRE ARP: 0 ( 0.000%) GRE IPX: 0 ( 0.000%) GRE Loop: 0 ( 0.000%) MPLS: 0 ( 0.000%) ARP: 0 ( 0.000%) IPX: 0 ( 0.000%) Eth Loop: 0 ( 0.000%) Eth Disc: 0 ( 0.000%) IP4 Disc: 0 ( 0.000%) IP6 Disc: 0 ( 0.000%) TCP Disc: 0 ( 0.000%) UDP Disc: 0 ( 0.000%) ICMP Disc: 0 ( 0.000%) All Discard: 0 ( 0.000%) Other: 0 ( 0.000%) Bad Chk Sum: 0 ( 0.000%) Bad TTL: 0 ( 0.000%) S5 G 1: 3 ( 0.090%) S5 G 2: 4 ( 0.120%) Total: 3333 =============================================================================== Action Stats: Alerts: 0 ( 0.000%) Logged: 0 ( 0.000%) Passed: 0 ( 0.000%) Limits: Match: 0 Queue: 0 Log: 0 Event: 0 Alert: 0 Verdicts: Allow: 3326 (100.000%) Block: 0 ( 0.000%) Replace: 0 ( 0.000%) Whitelist: 0 ( 0.000%) Blacklist: 0 ( 0.000%) Ignore: 0 ( 0.000%) =============================================================================== Frag3 statistics: Total Fragments: 0 Frags Reassembled: 0 Discards: 0 Memory Faults: 0 Timeouts: 0 Overlaps: 0 Anomalies: 0 Alerts: 0 Drops: 0 FragTrackers Added: 0 FragTrackers Dumped: 0 FragTrackers Auto Freed: 0 Frag Nodes Inserted: 0 Frag Nodes Deleted: 0 =============================================================================== =============================================================================== Stream statistics: Total sessions: 24 TCP sessions: 14 UDP sessions: 10 ICMP sessions: 0 IP sessions: 0 TCP Prunes: 0 UDP Prunes: 0 ICMP Prunes: 0 IP Prunes: 0 TCP StreamTrackers Created: 14 TCP StreamTrackers Deleted: 14 TCP Timeouts: 0 TCP Overlaps: 0 TCP Segments Queued: 2394 TCP Segments Released: 2394 TCP Rebuilt Packets: 793 TCP Segments Used: 2393 TCP Discards: 0 TCP Gaps: 0 UDP Sessions Created: 10 UDP Sessions Deleted: 10 UDP Timeouts: 0 UDP Discards: 0 Events: 1 Internal Events: 0 TCP Port Filter Filtered: 0 Inspected: 0 Tracked: 3286 UDP Port Filter Filtered: 0 Inspected: 0 Tracked: 10 =============================================================================== HTTP Inspect - encodings (Note: stream-reassembled packets included): POST methods: 0 GET methods: 10 HTTP Request Headers extracted: 10 HTTP Request Cookies extracted: 0 Post parameters extracted: 0 HTTP response Headers extracted: 10 HTTP Response Cookies extracted: 0 Unicode: 0 Double unicode: 0 Non-ASCII representable: 0 Directory traversals: 0 Extra slashes ("//"): 0 Self-referencing paths ("./"): 0 HTTP Response Gzip packets extracted: 0 Gzip Compressed Data Processed: n/a Gzip Decompressed Data Processed: n/a Total packets processed: 2433 =============================================================================== SMTP Preprocessor Statistics Total sessions : 0 Max concurrent sessions : 0 =============================================================================== dcerpc2 Preprocessor Statistics Total sessions: 0 =============================================================================== =============================================================================== SIP Preprocessor Statistics Total sessions: 0 =============================================================================== File Preprocessor Statistics Total file type callbacks: 7 Total file signature callbacks: 7 Total files would saved to disk: 7 Total files saved to disk: 7 Total file data saved to disk: 47466737 bytes Total files duplicated: 0 Total files reserving failed: 0 Total file capture min: 0 Total file capture max: 0 Total file capture memcap: 0 Total files reading failed: 0 Total file agent memcap failures: 0 Total files sent: 0 Total file data sent: 0 Total file transfer failures: 0 =============================================================================== File type stats: Type Download (Bytes) Upload (Bytes) GZ( 33) 2 6848054 0 0 MP3( 64) 2 37257592 0 0 JPEG( 70) 2 3360645 0 0 BMP(148) 1 446 0 0 Total 7 47466737 0 0 File signature stats: Type Download Upload GZ( 33) 2 0 MP3( 64) 2 0 PNG( 69) 1 0 JPEG( 70) 2 0 Total 7 0 File type verdicts: UNKNOWN: 7 LOG: 0 STOP: 0 BLOCK: 0 REJECT: 0 PENDING: 0 STOP CAPTURE: 0 Total: 7 File signature verdicts: UNKNOWN: 7 LOG: 0 STOP: 0 BLOCK: 0 REJECT: 0 PENDING: 0 STOP CAPTURE: 0 Total: 7 Total files processed: 10 Total files data processed: 47473897 bytes Total files buffered: 7 Total files released: 7 Total files freed: 0 Total files captured: 7 Total files within one packet: 1 Total buffers allocated: 1452 Total buffers freed: 0 Total buffers released: 1452 Maximum file buffers used: 759 Total buffers free errors: 0 Total buffers release errors: 0 Total memcap failures: 0 Total memcap failures at reserve: 0 Total reserve failures: 0 Total file capture size min: 0 Total file capture size max: 0 Total capture max before reserve: 0 Total file signature max: 0 Maximum buffers can allocate: 3196 Number of buffers in use: 0 Number of buffers in free list: 1744 Number of buffers in release list: 1452 =============================================================================== Snort exiting This time the captured files have changed: # ls -lS -rw------- 1 root root 24211979 May 8 21:20 8452B621DC334D1FD44470A80540CBEF2F6869AF851B9E8C684EF9402016F692 -rw------- 1 root root 13045613 May 8 21:20 5CF142947C2957EE648457A91B69FB82F088F31205030F9A77B2AD827228C6E9 -rw------- 1 root root 6352738 May 8 21:20 DB57C532919D9ABABAC127F29DBDC05ED832394880E46CAD81A5DDE713CCB4BE -rw------- 1 root root 2936119 May 8 21:20 B4127F43A3F455523B81179CC11AA4F28FC27F4C041D20E28AA08A32D85CB757 -rw------- 1 root root 495316 May 8 21:20 A294AA3D01CD8902BF842D320E7F2C043AF9EAD95D0E7198C3B71A0DBC9D253C -rw------- 1 root root 424526 May 8 21:20 8863DB1EC4B02D5BCC1FB4BD03D220F7458136342CDD47CE507A5B886C6BB56C -rw------- 1 root root 446 May 8 21:20 8D490C71A27631CF6A476F68C409655CB63BF32C17846A3C3C125A79046DB2C1 But they are still different from the original ones: # ls -lS -rw-r--r-- 1 root root 1044381696 Feb 18 20:12 ubuntu-14.04.2-desktop-amd64.iso -rw-r--r-- 1 root root 375187792 May 8 21:07 VMware-viclient.exe -rw-r--r-- 1 root root 101688487 Jul 10 2014 oversize_pdf_test_0.pdf -rw-r--r-- 1 root root 14955972 May 8 21:07 MakeUp.mov -rw-r--r-- 1 root root 6094376 May 8 21:07 video1.avi -rw-r--r-- 1 root root 2187725 May 8 21:07 Fighter.mpg -rw-r--r-- 1 root root 446 Mar 22 2013 tux-sw.bmp ########################################################################## ########################################################################## Exit stats when listening from interface and type_id enabled: =============================================================================== Run time for packet processing was 108.388974 seconds Snort processed 256250 packets. Snort ran for 0 days 0 hours 1 minutes 48 seconds Pkts/min: 256250 Pkts/sec: 2372 =============================================================================== Memory usage summary: Total non-mmapped bytes (arena): 10100736 Bytes in mapped regions (hblkhd): 122081280 Total allocated space (uordblks): 8073952 Total free space (fordblks): 2026784 Topmost releasable block (keepcost): 108544 =============================================================================== Packet I/O Totals: Received: 256250 Analyzed: 256250 (100.000%) Dropped: 0 ( 0.000%) Filtered: 0 ( 0.000%) Outstanding: 0 ( 0.000%) Injected: 0 =============================================================================== Breakdown by protocol (includes rebuilt packets): Eth: 256255 (100.000%) VLAN: 0 ( 0.000%) IP4: 256130 ( 99.951%) Frag: 0 ( 0.000%) ICMP: 0 ( 0.000%) UDP: 24 ( 0.009%) TCP: 132229 ( 51.601%) IP6: 0 ( 0.000%) IP6 Ext: 0 ( 0.000%) IP6 Opts: 0 ( 0.000%) Frag6: 0 ( 0.000%) ICMP6: 0 ( 0.000%) UDP6: 0 ( 0.000%) TCP6: 0 ( 0.000%) Teredo: 0 ( 0.000%) ICMP-IP: 0 ( 0.000%) IP4/IP4: 0 ( 0.000%) IP4/IP6: 0 ( 0.000%) IP6/IP4: 0 ( 0.000%) IP6/IP6: 0 ( 0.000%) GRE: 0 ( 0.000%) GRE Eth: 0 ( 0.000%) GRE VLAN: 0 ( 0.000%) GRE IP4: 0 ( 0.000%) GRE IP6: 0 ( 0.000%) GRE IP6 Ext: 0 ( 0.000%) GRE PPTP: 0 ( 0.000%) GRE ARP: 0 ( 0.000%) GRE IPX: 0 ( 0.000%) GRE Loop: 0 ( 0.000%) MPLS: 0 ( 0.000%) ARP: 125 ( 0.049%) IPX: 0 ( 0.000%) Eth Loop: 0 ( 0.000%) Eth Disc: 0 ( 0.000%) IP4 Disc: 123866 ( 48.337%) IP6 Disc: 0 ( 0.000%) TCP Disc: 0 ( 0.000%) UDP Disc: 0 ( 0.000%) ICMP Disc: 0 ( 0.000%) All Discard: 123866 ( 48.337%) Other: 11 ( 0.004%) Bad Chk Sum: 362 ( 0.141%) Bad TTL: 0 ( 0.000%) S5 G 1: 2 ( 0.001%) S5 G 2: 3 ( 0.001%) Total: 256255 =============================================================================== Action Stats: Alerts: 0 ( 0.000%) Logged: 0 ( 0.000%) Passed: 0 ( 0.000%) Limits: Match: 0 Queue: 0 Log: 0 Event: 0 Alert: 0 Verdicts: Allow: 228770 ( 89.276%) Block: 0 ( 0.000%) Replace: 0 ( 0.000%) Whitelist: 27480 ( 10.724%) Blacklist: 0 ( 0.000%) Ignore: 0 ( 0.000%) =============================================================================== Frag3 statistics: Total Fragments: 0 Frags Reassembled: 0 Discards: 0 Memory Faults: 0 Timeouts: 0 Overlaps: 0 Anomalies: 0 Alerts: 0 Drops: 0 FragTrackers Added: 0 FragTrackers Dumped: 0 FragTrackers Auto Freed: 0 Frag Nodes Inserted: 0 Frag Nodes Deleted: 0 =============================================================================== =============================================================================== Stream statistics: Total sessions: 20 TCP sessions: 14 UDP sessions: 6 ICMP sessions: 0 IP sessions: 0 TCP Prunes: 0 UDP Prunes: 0 ICMP Prunes: 0 IP Prunes: 0 TCP StreamTrackers Created: 14 TCP StreamTrackers Deleted: 14 TCP Timeouts: 0 TCP Overlaps: 0 TCP Segments Queued: 6930 TCP Segments Released: 6930 TCP Rebuilt Packets: 6331 TCP Segments Used: 6903 TCP Discards: 7 TCP Gaps: 6570 UDP Sessions Created: 6 UDP Sessions Deleted: 6 UDP Timeouts: 0 UDP Discards: 0 Events: 16 Internal Events: 0 TCP Port Filter Filtered: 0 Inspected: 0 Tracked: 131874 UDP Port Filter Filtered: 0 Inspected: 0 Tracked: 6 =============================================================================== HTTP Inspect - encodings (Note: stream-reassembled packets included): POST methods: 0 GET methods: 0 HTTP Request Headers extracted: 0 HTTP Request Cookies extracted: 0 Post parameters extracted: 0 HTTP response Headers extracted: 2 HTTP Response Cookies extracted: 0 Unicode: 0 Double unicode: 0 Non-ASCII representable: 0 Directory traversals: 0 Extra slashes ("//"): 0 Self-referencing paths ("./"): 0 HTTP Response Gzip packets extracted: 0 Gzip Compressed Data Processed: n/a Gzip Decompressed Data Processed: n/a Total packets processed: 13165 =============================================================================== SMTP Preprocessor Statistics Total sessions : 0 Max concurrent sessions : 0 =============================================================================== dcerpc2 Preprocessor Statistics Total sessions: 0 =============================================================================== SSL Preprocessor: SSL packets decoded: 68 Client Hello: 0 Server Hello: 2 Certificate: 2 Server Done: 3 Client Key Exchange: 0 Server Key Exchange: 0 Change Cipher: 2 Finished: 0 Client Application: 0 Server Application: 1 Alert: 0 Unrecognized records: 64 Completed handshakes: 0 Bad handshakes: 0 Sessions ignored: 1 Detection disabled: 1 =============================================================================== SIP Preprocessor Statistics Total sessions: 0 =============================================================================== File Preprocessor Statistics Total file type callbacks: 2 Total file signature callbacks: 1 Total files would saved to disk: 1 Total files saved to disk: 1 Total file data saved to disk: 446 bytes Total files duplicated: 0 Total files reserving failed: 0 Total file capture min: 0 Total file capture max: 0 Total file capture memcap: 0 Total files reading failed: 0 Total file agent memcap failures: 0 Total files sent: 0 Total file data sent: 0 Total file transfer failures: 0 =============================================================================== File type stats: Type Download (Bytes) Upload (Bytes) BMP(148) 1 446 0 0 PDF(288) 1 3057259 0 0 Total 2 3057705 0 0 File signature stats: Type Download Upload BMP(148) 1 0 Total 1 0 File type verdicts: UNKNOWN: 2 LOG: 0 STOP: 0 BLOCK: 0 REJECT: 0 PENDING: 0 STOP CAPTURE: 0 Total: 2 File signature verdicts: UNKNOWN: 1 LOG: 0 STOP: 0 BLOCK: 0 REJECT: 0 PENDING: 0 STOP CAPTURE: 0 Total: 1 Total files processed: 2 Total files data processed: 3057705 bytes Total files buffered: 2 Total files released: 1 Total files freed: 1 Total files captured: 1 Total files within one packet: 1 Total buffers allocated: 95 Total buffers freed: 94 Total buffers released: 1 Maximum file buffers used: 94 Total buffers free errors: 0 Total buffers release errors: 0 Total memcap failures: 0 Total memcap failures at reserve: 0 Total reserve failures: 0 Total file capture size min: 0 Total file capture size max: 0 Total capture max before reserve: 0 Total file signature max: 0 Maximum buffers can allocate: 3196 Number of buffers in use: 0 Number of buffers in free list: 3195 Number of buffers in release list: 1 =============================================================================== Snort exiting This time the captured files haven't changed: # ls -lS -rw------- 1 root root 446 May 8 21:33 8D490C71A27631CF6A476F68C409655CB63BF32C17846A3C3C125A79046DB2C1 Best Regards, Pablo Cantos redborder.org <http://redborder.org> / pcantos () redborder org <mailto:pcantos () redborder org> 2015-05-08 21:49 GMT+02:00 Hui Cao (huica) <huica () cisco com <mailto:huica () cisco com>>: Hi Pablo, When listening from interfaces, you have lots of discards. Because file processing relies on data that are reassembled correctly, it won’t be called for those sessions that miss file data. In the case of PCAP, no sure why file type is not identified. It is interesting to see 47M file data for only 3326 packets. That is 24K per packet. I guess in this case, it will always hit PAF_MAX for each packet which might set each packet as single PDU(file). Can you try this setting? config paf_max: 60000 Best, Hui. From: Pablo Cantos Polaino <pcantos () redborder org <mailto:pcantos () redborder org>> Date: Friday, May 8, 2015 at 3:29 PM To: Hui Cao <huica () cisco com <mailto:huica () cisco com>> Cc: "snort-users () lists sourceforge net <mailto:snort-users () lists sourceforge net>" <snort-users () lists sourceforge net <mailto:snort-users () lists sourceforge net>> Subject: Re: [Snort-users] File preprocessor fails to capture files IP4 Disc: 122145 ( 49.331%) IP6 Disc: 0 ( 0.000%) TCP Disc: 0 ( 0.000%) UDP Disc: 0 ( 0.000%) ICMP Disc: 0 ( 0.000%) All Discard: 122145 ( 49.331%) TCP Segments Used: 6919 TCP Discards: 48 TCP Gaps: 6459 ------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y _______________________________________________ Snort-users mailing list Snort-users () lists sourceforge net Go to this URL to change user options or unsubscribe: https://lists.sourceforge.net/lists/listinfo/snort-users Snort-users list archive: http://sourceforge.net/mailarchive/forum.php?forum_name=snort-users Please visit http://blog.snort.org to stay current on all the latest Snort news!
------------------------------------------------------------------------------ One dashboard for servers and applications across Physical-Virtual-Cloud Widest out-of-the-box monitoring support with 50+ applications Performance metrics, stats and reports that give you Actionable Insights Deep dive visibility with transaction tracing using APM Insight. http://ad.doubleclick.net/ddm/clk/290420510;117567292;y
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Current thread:
- File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui cao (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 15)
- Re: File preprocessor fails to capture files Russ (May 15)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 16)
- Re: File preprocessor fails to capture files Russ (May 17)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 18)
- Re: File preprocessor fails to capture files Pablo Cantos Polaino (May 08)
- Re: File preprocessor fails to capture files Hui Cao (huica) (May 08)