nanog mailing list archives
Re: Common operational misconceptions
From: Mark Andrews <marka () isc org>
Date: Fri, 17 Feb 2012 07:22:42 +1100
In message <20120216165308.GE65401 () macbook bluepipe net>, Phil Regnauld writes:
Borderline dns-ops, sorry folks! - but this is interesting as we've been talking about ipv6 being operational, and this is part of it... Mark Andrews (marka) writes:If you are seeing TC between the resolver and the server and the TCP query is being answers then something in the path is intercepting the DNS queries.TC is on the answer from the remote server to my resolver, so yeah, seems like something is messing with the packets.Don't see any v6 fragments (that'd be a problem since PF doesn't handle them on this host).You should see something like this on the wire. The second query is to answer dig's query over TCP.I'm not seeing fragments as you are. Here's what I see: 14:40:20.955876 IP6 2001:2000:1080:d::2.64561 > 2001:4f8:0:2::8.53: 52841 TXT? edns-v6-ok.isc.org. (36) 14:40:21.141948 IP6 2001:4f8:0:2::8.53 > 2001:2000:1080:d::2.64561: 52841*-| 0/0/0 (36) 14:40:21.142259 IP6 2001:2000:1080:d::2.53262 > 2001:4f8:0:2::8.53: Flags [S], seq 1112939462, win 65535, optio ns [mss 1440,nop,wscale 6,sackOK,TS val 2571957531 ecr 0], length 0 14:40:21.327895 IP6 2001:4f8:0:2::8.53 > 2001:2000:1080:d::2.53262: Flags [R.], seq 0, ack 1112939463, win 0, l ength 0
Which means you are seeing named in fallback mode, or have configured named to not take EDNS to this server. In anycase your firewall is misconfigured/broken if it is blocking fragments.
Cheers, Phil
-- Mark Andrews, ISC 1 Seymour St., Dundas Valley, NSW 2117, Australia PHONE: +61 2 9871 4742 INTERNET: marka () isc org
Current thread:
- Re: Common operational misconceptions, (continued)
- Re: Common operational misconceptions Mark Andrews (Feb 15)
- Re: Common operational misconceptions Masataka Ohta (Feb 15)
- Re: Common operational misconceptions Steve Bertrand (Feb 15)
- Re: Common operational misconceptions sthaug (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Jeroen Massar (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Phil Regnauld (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Phil Regnauld (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Daniel Griggs (Feb 16)
- Re: Common operational misconceptions Mark Andrews (Feb 16)
- Re: Common operational misconceptions Owen DeLong (Feb 15)
- Re: Common operational misconceptions Paul Thornton (Feb 16)
- Re: Common operational misconceptions Jared Mauch (Feb 16)
- Re: Common operational misconceptions Owen DeLong (Feb 16)
- Re: Common operational misconceptions Ray Soucy (Feb 16)
- Re: Common operational misconceptions Jeff Kell (Feb 16)
- Re: Common operational misconceptions Chuck Anderson (Feb 16)
- Re: Common operational misconceptions Jack Bates (Feb 16)