Snort mailing list archives
Re: Snort 2.0.4 CPU Utilization\Optimization
From: "Jason Haar" <Jason.Haar () trimble co nz>
Date: Sat, 22 Nov 2003 17:33:09 +1300 (NZDT)
Matt Kettler said:
DNS can be done over TCP as well as UDP, although TCP is much less common most DNS servers support both. Usually TCP is only used for larger queries like large zone transfers.
DNS zone transfers are *exclusively* done over TCP - never UDP. If you don't need zone transfers, and know that your DNS records are non-complex (no chaining CNAMEs, only a few MX records/etc), then in fact no-one even needs to do TCP-based DNS queries off you either. TCP is only used for large answers (I think the DNS server gives a partial answer over UDP, and then the client re-tries the same query over TCP, where they receive the full answer. TCP of course is reliable - so is used for large answers and zone transfers). For years I have been running our DMZ DNS servers as UDP-only (i.e. firewall allows UDP port 53 only), and no-one has any issues doing DNS lookups against us. Obviously I still have to allow our DNS caching servers to do both TCP and UDP outbound - as there are some records that are too large for UDP - so TCP is used. (getting a bit OT here ;-)
It's also a preferred connection method when exploiting DNS servers, since it's easier to get a shell on a two-way connection.
Yup - that's why it was really nice to drop it all together :-) Jason ------------------------------------------------------- This SF.net email is sponsored by: SF.net Giveback Program. Does SourceForge.net help you be more productive? Does it help you create better code? SHARE THE LOVE, and help us help YOU! Click Here: http://sourceforge.net/donate/ _______________________________________________ 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:
- Re: Snort 2.0.4 CPU Utilization\Optimization, (continued)
- Re: Snort 2.0.4 CPU Utilization\Optimization Edin Dizdarevic (Nov 21)
- Re: Snort 2.0.4 CPU Utilization\Optimization Edin Dizdarevic (Nov 21)
- Re: Snort 2.0.4 CPU Utilization\Optimization Matt Kettler (Nov 21)
- Re: Snort 2.0.4 CPU Utilization\Optimization Edin Dizdarevic (Nov 21)
- RE: Snort 2.0.4 CPU Utilization\Optimization Tim (Nov 21)
- RE: Snort 2.0.4 CPU Utilization\Optimization Mark Ewert (Nov 20)
- RE: Snort 2.0.4 CPU Utilization\Optimization Kreimendahl, Chad J (Nov 20)
- RE: Snort 2.0.4 CPU Utilization\Optimization Mark Ewert (Nov 21)
- RE: Snort 2.0.4 CPU Utilization\Optimization Mark Ewert (Nov 21)
- RE: Snort 2.0.4 CPU Utilization\Optimization Kreimendahl, Chad J (Nov 21)
- Re: Snort 2.0.4 CPU Utilization\Optimization Jason Haar (Nov 21)
- Re: Snort 2.0.4 CPU Utilization\Optimization Edin Dizdarevic (Nov 21)