Snort mailing list archives
RE: Kernel Dropping Packets
From: "Arseneault, Thomas (HQP)" <thomas.arseneault () rhi com>
Date: Wed, 9 Mar 2005 12:21:29 -0800
Logging to the console is rate limited depending on the OS your using. I've had Solaris machines with consoles limited to 9600 baud. I don't recall right now how/where to check your console speed but that is what I'd bet the problem is. You start writing to the console and the buffer fills up and blocks the text steam causing the kernel to stop processing packets, you processor is fine and more than capable of keeping up but it's told not to. Files will write as fast as he platter and heads and interface will let you. You might be able to increase the speed of the console but you'll get to a point, early on, where the stream speeds by too fast to be of any use and any thing interesting will flow past the end of the scroll back buffer. Tom Arseneault Security Engineer Robert Half International -----Original Message----- From: snort-users-admin () lists sourceforge net [mailto:snort-users-admin () lists sourceforge net] On Behalf Of sEc nErD Sent: Wednesday, March 09, 2005 8:58 AM To: Snort-users () lists sourceforge net Subject: [Snort-users] Kernel Dropping Packets Hi ALL, I stopped my snort ,Whenevr i use tcp dump on the sniffing interfaces to write tot he console kernel drops 90% of the packets , but when i do tcp dump to write to a file whatever ti sniffs it kernel drops zero packets. Since writing to file requires less cpu usage and kernel doesnt drop anything ,i am assuming my pcap is just working fine....but when we write tot he console...the cpu cannot process info from pcap as fast....?? But my proccessor info and others dont give me any resource crunch unless am interpreting them wrong..please let me know what cud be the issue thanks any help on that below are outputs of meminfo,cpu info and top -c #cat cpuinfo processor : 1 vendor_id : GenuineIntel cpu family : 15 model : 4 model name : Intel(R) Pentium(R) 4 CPU 3.00GHz stepping : 1 cpu MHz : 2996.236 cache size : 1024 KB physical id : 0 siblings : 2 fdiv_bug : no hlt_bug : no f00f_bug : no coma_bug : no fpu : yes fpu_exception : yes cpuid level : 5 wp : yes flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe pni monitor ds_cpl cid bogomips : 5980.16 #cat meminfo cat meminfo MemTotal: 1034584 kB MemFree: 437504 kB Buffers: 123512 kB Cached: 222808 kB SwapCached: 0 kB Active: 336500 kB Inactive: 172152 kB HighTotal: 0 kB HighFree: 0 kB LowTotal: 1034584 kB LowFree: 437504 kB SwapTotal: 2040244 kB SwapFree: 2040244 kB Dirty: 4 kB Writeback: 0 kB Mapped: 155860 kB Slab: 74228 kB Committed_AS: 247860 kB PageTables: 7340 kB VmallocTotal: 3088376 #top -c Cpu(s): 0.2% us, 0.0% sy, 0.0% ni, 99.8% id, 0.0% wa, 0.0% hi, 0.0% si Mem: 1034584k total, 597144k used, 437440k free, 123512k buffers Swap: 2040244k total, 0k used, 2040244k free, 222808k cach __________________________________ Celebrate Yahoo!'s 10th Birthday! Yahoo! Netrospective: 100 Moments of the Web http://birthday.yahoo.com/netrospective/ ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ 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://www.geocrawler.com/redir-sf.php3?list=snort-users ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click _______________________________________________ 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://www.geocrawler.com/redir-sf.php3?list=snort-users
Current thread:
- Kernel Dropping Packets sEc nErD (Mar 09)
- <Possible follow-ups>
- RE: Kernel Dropping Packets Arseneault, Thomas (HQP) (Mar 09)