diff options
| -rw-r--r-- | Makefile | 2 | ||||
| -rw-r--r-- | README.dbk | 49 | ||||
| -rw-r--r-- | README.txt | 44 |
3 files changed, 82 insertions, 13 deletions
@@ -30,5 +30,5 @@ README.txt: README.dbk xmlto text README.dbk README.html: README.dbk - xmlto xhtml README.dbk + xmlto xhtml-nochunks README.dbk @@ -175,13 +175,52 @@ ip6tables -t mangle -A FORWARD -p tcp --tcp-flags SYN,RST SYN -j TCPMSS --clamp- </section> <section> - <title>Hints (Chapter is To-do)</title> + <title>IPv6/IPv4 Precedence</title> - <para>Note on ubuntu. One needs to enable prefer-family in /etc/wgetrc. after this e.g. "wget -O /dev/null - http://ftp.se.debian.org" should connect to the IPv6 addrs of that server. Alternative: change presedence of ULAs in - /etc/gai.conf</para> + <para>With (EKU)buntu and eventually with RedHat, you will notice that your browser does not show the IPv6 version of a web + site that is multi-homed when using ULA addresses for your IPv6 Internet connection. The reason for this is an add on to the + RFC 3484 rules that is compiled into the (EKU)buntu libc. The pre-installed <filename>/etc/gai.conf</filename> file will + give you a hint on this.</para> - <para>Idea to think about: --salt 3b5b91c5a2 XOR client addresses for some more privacy</para> + <para>In short: the getaddrinfo() library function rates a private IPv4 address higher than the ULA IPv6 address when + choosing the transport protocol for a new Internet connection if this add on to the RFC 3484 rules is compiled in. For this + reason, you may want to change the precedence rules within <filename>/etc/gai.conf</filename>.</para> + + <note> + <para>The getaddrinfo() library function manages lists of label, precedence, and scope4 type entries. If the + <filename>/etc/gai.conf</filename> file does not provide a single entry for a particular type, the compiled-in list is + used. For this reason, you cannot uncomment a single entry to overwrite the default. You need to uncomment all entries of + a particular type for this. The <quote>label</quote> lines compare source addresses, the precedence lines compare + <quote>destination</quote> addresses.</para> + </note> + + <procedure> + <title>Change IPv6 Precedence</title> + + <step> + <para>Open the <filename>/etc/gai.conf</filename> file as root user, e.g. by executing <userinput>sudo nano + /etc/gai.conf</userinput>.</para> + </step> + + <step> + <para>Remove the leading hash character from the 8 lines starting with <quote>#label</quote>.</para> + </step> + + <step> + <para>Re-add the hash character to the line stating <quote>#label fc00::/7 6</quote>.</para> + </step> + + <step> + <para>Save the file.</para> + </step> + + <step> + <para>Restart your browser and re-try to browse to a multi-homed web site.</para> + </step> + </procedure> + + <para>The above procedure removes the difference between standard IPv6 source addresses and ULA type private IPv6 source + addresses. Anything else is unchanged.</para> </section> <section id="motivation"> @@ -17,7 +17,7 @@ Configuration Brief Version Detailed Version -Hints (Chapter is To-do) +IPv6/IPv4 Precedence Motivation These files implement a Linux netfilter target that changes the IPv6 address of @@ -186,14 +186,44 @@ address, you will get the answer packet back via the 6-to-4 interface. If the above address mapping is configured, you ping one IPv6 address and get the answer from another IPv6 address... -Hints (Chapter is To-do) +IPv6/IPv4 Precedence -Note on ubuntu. One needs to enable prefer-family in /etc/wgetrc. after this -e.g. "wget -O /dev/null http://ftp.se.debian.org" should connect to the IPv6 -addrs of that server. Alternative: change presedence of ULAs in /etc/gai.conf +With (EKU)buntu and eventually with RedHat, you will notice that your browser +does not show the IPv6 version of a web site that is multi-homed when using ULA +addresses for your IPv6 Internet connection. The reason for this is an add on +to the RFC 3484 rules that is compiled into the (EKU)buntu libc. The +pre-installed /etc/gai.conf file will give you a hint on this. -Idea to think about: --salt 3b5b91c5a2 XOR client addresses for some more -privacy +In short: the getaddrinfo() library function rates a private IPv4 address +higher than the ULA IPv6 address when choosing the transport protocol for a new +Internet connection if this add on to the RFC 3484 rules is compiled in. For +this reason, you may want to change the precedence rules within /etc/gai.conf. + +Note + +The getaddrinfo() library function manages lists of label, precedence, and +scope4 type entries. If the /etc/gai.conf file does not provide a single entry +for a particular type, the compiled-in list is used. For this reason, you +cannot uncomment a single entry to overwrite the default. You need to uncomment +all entries of a particular type for this. The “label” lines compare source +addresses, the precedence lines compare “destination” addresses. + +Procedure 1. Change IPv6 Precedence + + 1. Open the /etc/gai.conf file as root user, e.g. by executing sudo nano /etc/ + gai.conf. + + 2. Remove the leading hash character from the 8 lines starting with “#label”. + + 3. Re-add the hash character to the line stating “#label fc00::/7 6”. + + 4. Save the file. + + 5. Restart your browser and re-try to browse to a multi-homed web site. + +The above procedure removes the difference between standard IPv6 source +addresses and ULA type private IPv6 source addresses. Anything else is +unchanged. Motivation |