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Diffstat (limited to 'share/examples/IPv6/USAGE')
| -rw-r--r-- | share/examples/IPv6/USAGE | 34 |
1 files changed, 34 insertions, 0 deletions
diff --git a/share/examples/IPv6/USAGE b/share/examples/IPv6/USAGE index f9122c2..5a02037 100644 --- a/share/examples/IPv6/USAGE +++ b/share/examples/IPv6/USAGE @@ -626,4 +626,38 @@ Configuration at Host-A: -E rc5-cbc "kamekame" -A hmac-md5 "this is the test" ; +<<<EDNS0>>> + +EDNS0 is defined in RFC2671. With EDNS0, the resolver library can tell DNS +server of its receiving buffer size, and permit DNS server to transmit large +reply packet. EDNS0 is necessary to take advantage of larger minimum MTU +in IPv6. KAME libinet6 includes resolver side support for EDNS0. +Server side support for EDNS0 is included in ISC BIND9. + + query packet with EDNS0 + tells receive buffer size +KAME box -----------------------------> BIND9 DNS server +KAME box <----------------------------- BIND9 DNS server + can transmit jumbo reply, since DNS server + knows receive buffer size of KAME box + +How to play with it: +- prepare KAME box and BIND9 DNS server (can be a same node) +- add the following into /etc/resolv.conf on KAME box: + options edns0 <--- enables EDNS0 + nameserver <IPv4 or v6 address of BIND9 box> +- run applications compiled with libinet6 (like /usr/local/v6/bin/telnet), + see EDNS0 packet fly on the wire by tcpdump or some other method. + +Caveats: +- BIND 4/8 DNS server will choke with EDNS0 packet, so you must not + turn the option on if you have BIND 4/8 DNS server. If you enable + "options edns0" against BIND 4/8 DNS server, you will never be able + to resolve names. +- If you use IPv6 UDP as DNS transport, path MTU discovery may + affect the traffic. KAME box tries to fragment packet to 1280 + bytes, however, BIND9 may not. +- Some of our platforms do not use our extended resolver code in libinet6. + See COVERAGE for detail. + <end of USAGE> |
