Hello, interesting ...
----- PŮVODNÍ ZPRÁVA ----- Od: "Stacey Marshall" <[email protected]> Komu: "kapetr" <[email protected]> Předmět: Re: BIND9 fails resolving after connecting to VPN Datum: 9.4.2011 - 22:50:44 > I' wondering if the network your attaching to via > VPN allows direct DNS > lookups? > > I know of networks where the provided servers have > firewall rules that allow > them to make queries but other servers are not. > > You could test this theory by trying to connect to > a root server with dig > when connected to VPN. For example: > > $ dig @h.root-servers.net. www.seznam.cz > > Regards, Stace Why should VPN provider filter (disable) direct queries and allow only recursive queries ? The results are (for me) surprising: 1. before VPN: my (127.0.0.1) and ISPs servers work OK and: ******************************************************************** hugo@duron650:~$ dig @h.root-servers.net. www.seznam.cz ; <<>> DiG 9.7.1-P2 <<>> @h.root-servers.net. www.seznam.cz ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 20035 ;; flags: qr rd; QUERY: 1, ANSWER: 0, AUTHORITY: 5, ADDITIONAL: 10 ;; WARNING: recursion requested but not available ;; QUESTION SECTION: ;www.seznam.cz. IN A ;; AUTHORITY SECTION: cz. 172800 IN NS a.ns.nic.cz. cz. 172800 IN NS b.ns.nic.cz. cz. 172800 IN NS c.ns.nic.cz. cz. 172800 IN NS d.ns.nic.cz. cz. 172800 IN NS f.ns.nic.cz. ;; ADDITIONAL SECTION: a.ns.nic.cz. 172800 IN A 194.0.12.1 b.ns.nic.cz. 172800 IN A 194.0.13.1 c.ns.nic.cz. 172800 IN A 194.0.14.1 d.ns.nic.cz. 172800 IN A 193.29.206.1 f.ns.nic.cz. 172800 IN A 193.171.255.48 a.ns.nic.cz. 172800 IN AAAA 2001:678:f::1 b.ns.nic.cz. 172800 IN AAAA 2001:678:10::1 c.ns.nic.cz. 172800 IN AAAA 2001:678:11::1 d.ns.nic.cz. 172800 IN AAAA 2001:678:1::1 f.ns.nic.cz. 172800 IN AAAA 2001:628:453:420::48 ;; Query time: 144 msec ;; SERVER: 128.63.2.53#53(128.63.2.53) ;; WHEN: Mon Apr 11 12:56:18 2011 ;; MSG SIZE rcvd: 338 hugo@duron650:~$ 2. after VPN up: **************************************************************** - my (127.0.0.1) fails again - "connection timed out; no servers could be reached" - ISPs server OK again - I get normal "A" answer - DNS root server - by name (IP get from ISPs server) or by IP gives: hugo@duron650:~$ dig @h.root-servers.net. www.seznam.cz ; <<>> DiG 9.7.1-P2 <<>> @h.root-servers.net. www.seznam.cz ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2758 ;; flags: qr rd ra; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0 ;; QUESTION SECTION: ;www.seznam.cz. IN A ;; ANSWER SECTION: www.seznam.cz. 203 IN A 77.75.72.3 ;; Query time: 67 msec ;; SERVER: 128.63.2.53#53(128.63.2.53) ;; WHEN: Mon Apr 11 12:58:52 2011 ;; MSG SIZE rcvd: 47 hugo@duron650:~$ ************************************************* So why the h.root-servers.net == 128.63.2.53 in case 2 (over VPN) gives the recursive answer ? Do You thing, that this VPN provider - blocks direct (not recursive) DNS questions and - manipulates recursive queries ? [catch them, make query itself and answers with manipulated server IP] ??? --kapetr _______________________________________________ bind-users mailing list [email protected] https://lists.isc.org/mailman/listinfo/bind-users
