joeforker's questions

On a Linux machine connected to the ipv6 internet via a router's radvd-advertised tunnel, ip -6 route accumulates recent addresses. Why does this happen? Is it expected behavior, or is the machine misconfigured? On a different machine that is connected to an ipv6 tunnel directly, ip -6 route keeps a shorter list.

On the client (which is accumulating recent addresses as routes):

ip -6 route # after pinging ipv6.google.com and www.kame.net

2001:200:dff:fff1:216:3eff:feb1:44d7 via fe80::216:1ff:fe14:444 dev eth0  proto static  metric 1024 
2001:470:8:e7c::/64 dev eth0  proto kernel  metric 256  expires 86407sec
2607:f8b0:4002:801::1011 via fe80::216:1ff:fe14:444 dev eth0  proto static  metric 1024 
fe80::/64 dev eth0  proto kernel  metric 256 
default via fe80::216:1ff:fe14:444 dev eth0  proto kernel  metric 1024 

On the router:

    ip -6 route
    ::/96 via :: dev tun6to4  metric 256  mtu 1280 advmss 1220
    2001:470:7:e7c::/64 via :: dev he-ipv6  metric 256  mtu 1480 advmss 1420
    2001:470:8:e7c::/64 dev br0  metric 256  mtu 1500 advmss 1440
    2002:62b4:2270:1::/64 dev br0  metric 256  mtu 1500 advmss 1440
    2002::/16 dev tun6to4  metric 256  mtu 1280 advmss 1220
    2000::/3 dev he-ipv6  metric 1024  mtu 1480 advmss 1420
    fe80::/64 dev eth0  metric 256  mtu 1500 advmss 1440
    fe80::/64 dev vlan0  metric 256  mtu 1500 advmss 1440
    fe80::/64 dev eth1  metric 256  mtu 1500 advmss 1440
    fe80::/64 dev br0  metric 256  mtu 1500 advmss 1440
    fe80::/64 dev vlan1  metric 256  mtu 1500 advmss 1440
    fe80::/64 via :: dev he-ipv6  metric 256  mtu 1480 advmss 1420
    fe80::/64 dev tun6to4  metric 256  mtu 1280 advmss 1220
    ff00::/8 dev eth0  metric 256  mtu 1500 advmss 1440
    ff00::/8 dev vlan0  metric 256  mtu 1500 advmss 1440
    ff00::/8 dev eth1  metric 256  mtu 1500 advmss 1440
    ff00::/8 dev br0  metric 256  mtu 1500 advmss 1440
    ff00::/8 dev vlan1  metric 256  mtu 1500 advmss 1440
    ff00::/8 dev he-ipv6  metric 256  mtu 1480 advmss 1420
    ff00::/8 dev tun6to4  metric 256  mtu 1280 advmss 1220
    default dev he-ipv6  metric 1024  mtu 1480 advmss 1420

ip -6 a
1: lo: <LOOPBACK,MULTICAST,UP>
    inet6 ::1/128 scope host
3: eth0: <BROADCAST,MULTICAST,PROMISC,UP>
    inet6 fe80::216:1ff:fe14:444/64 scope link
4: eth1: <BROADCAST,MULTICAST,PROMISC,UP>
    inet6 fe80::216:1ff:fe14:446/64 scope link
5: vlan0: <BROADCAST,MULTICAST,PROMISC,UP>
    inet6 fe80::216:1ff:fe14:444/64 scope link
6: vlan1: <BROADCAST,MULTICAST,UP>
    inet6 fe80::216:1ff:fe14:445/64 scope link
8: br0: <BROADCAST,MULTICAST,PROMISC,UP>
    inet6 fe80::216:1ff:fe14:444/64 scope link
    inet6 2002:62b4:2270:1::1/64 scope global
    inet6 2001:470:8:e7c::1/64 scope global
12: he-ipv6: <POINTOPOINT,NOARP,UP>
    inet6 2001:470:7:e7c::2/64 scope global
    inet6 fe80::62b4:2270/128 scope link
13: tun6to4: <NOARP,UP>
    inet6 2002:62b4:2270::1/16 scope global
    inet6 ::98.180.34.112/128 scope global

radvd.conf:

interface br0 {
AdvSendAdvert on;
prefix 2001:470:8:e7c::/64 {
AdvOnLink on;
AdvAutonomous on;
AdvRouterAddr off;
};
};

I would like the ATI graphics to default to a known working state when a user logs into Windows XP, regardless of whether that user has tried to change the settings. How do I make that happen?

Linux has a PAM module that manipulates cgroups. How is it configured (what options does it support?)

I am trying to compress certain content from a reverse proxy by using mod_filter. The only way to know the mime type of the content is by inspecting the Content-Type header from the back end. The request URI is not a useful selector here because the system (Plone) keeps track of mime types without regard to filename or location.

This configuration seems to do basically what I want, compressing everything and then decompressing it again if it is an application, but that seems like a waste.

I would rather be able to AND and OR multiple conditions to decide whether to apply compression, duplicating the SetOutputFilter DEFLATE setup from the docs that everyone uses in a way that works with ProxyPass.

Is it possible to AND multiple conditions for mod_filter's FilterProvider?

ProxyPass / http://localhost:8080/
<Location />
    FilterDeclare gzip CONTENT_SET
    FilterDeclare gzipinflate CONTENT_SET
    FilterDeclare gzipinflate2 CONTENT_SET
    FilterProvider gzip deflate req=Accept-Encoding $gzip
    FilterProvider gzipinflate inflate resp=Content-Type $application/
    FilterChain +gzip +gzipinflate
</Location>

How do I access an environment variable (from the puppet daemon's environment) in a puppet manifest?

Does puppet have a way to install a yum package group (e.g. 'Development Tools'), besides exec?

I'm using cfengine to start the foobar process. Apparently the LHS is discarded when I use process_select? Can I simply pass the LHS to a function, rather than having to put the command match pattern in a body argument?

I wanted to only match foobar processes belonging to a particular user, since another user could easily be running foobar for testing.

bundle agent foobar {
processes:
    "foobar" # documented way would be to use .* here
        process_select => command("foobar"),
        restart_class => start_foobar;

commands:
    start_foobar::
        "/usr/bin/foobar";
}

body process_select command(c) {
    command => "$(c)";
    process_result => "command";
}

How do I read a pid file in cfengine 3 and restart that process if it isn't running?

I would like to set a class in cfengine3 so I can perform an action if the disk is almost full.

Sometimes it is useful to have e-mail address like [email protected], where randomnumber identifies the conversation between a robot such as a mailing list server and a user. Is this possible with Microsoft Exchange?

I'm using 6to4. How do I configure reverse DNS for my site? It's a Linux server, I'm using freedns.afraid.org and am not running bind.

Our systems cannot send e-mail to a company that has no MX record. There is an SMTP server running on their IP address and they are able to get e-mail from gmail. Is it normal for mail systems to try to connect to a SMTP server at the A record when there is no MX?

Apache's default configuration includes something like this in ssl.conf:

SetEnvIf User-Agent ".*MSIE.*"
    nokeepalive ssl-unclean-shutdown
    downgrade-1.0 force-response-1.0

Do newer IE still require all of these workarounds?

I have a Linux router without an ipv6 stack and a Linux host inside the NAT. How do I use iptables to forward 6to4 traffic back and forth between the NAT router and the host and then configure the 6to4 tunnel on the host using the router's public IPv4 address?

This recipe (on the router) gets an ipv6 ping to the host's eth0 but they don't make it onto the tun6to4 interface. Wireshark says "ICMP Destination unreachable (Port unreachable)" as an ipv4 response to the 6to4 ping.

# inbound destination NAT for IPv6 tunnel. ppp0 is router's WAN interface.
iptables -t nat -A PREROUTING -i ppp0 -p 41 -j DNAT --to 192.168.1.100
# inbound forwarding for IPv6 tunnel
iptables -t filter -A FORWARD -i ppp0 -p 41 -d 192.168.1.100 -j ACCEPT

I am using this script on the Linux host, passing the router's public ip:

#!/bin/bash

### Get the global IPv4 address for your host from the command line:
GLOB_IP4=$1

### Compute the 6TO4 tunnel IPv6 address:
GLOB_IP6TO4=$(printf "2002:%02x%02x:%02x%02x::1" $(echo $GLOB_IP4 | tr . ' '))

### Setup the tunnel
ip tunnel add tun6to4 mode sit remote any local $GLOB_IP4 ttl 64
ip link set dev tun6to4 up
ip addr add $GLOB_IP6TO4/16 dev tun6to4
ip route add 2000::/3 via ::192.88.99.1 dev tun6to4 metric 1

On 64-bit RHEL5 running Java 1.6.0 update 16, root can successfully run a Java program but a user can't because libjli.so supposedly can't be found. SELinux is turned off and the environment is the same before the program is run. I've tried putting libjli.so in the LD_LIBRARY_PATH but it doesn't make a difference.

How do I fix this error?

Right now I'm using Mercurial to synchronize similar Apache configurations between the production and development servers. A patch queue on top of that adds in the changes and extra stuff required for the development server.

The scheme works but it could be better. I always get merge conflicts when I reapply the patch queue after pulling changes from the deployment configs. I feel like I am always making identical changes to the separate http:// and https:// config files.

How should I factor out the identical bits between my :80 and :443 Apache configs and more cleanly add in the "extra bits" to the development config?

How does pam decide which files in /etc/pam.d to use depending on whether a user logs in via ssh, locally, a serial console, etc?

I'm trying to back up 66 gigabytes to a NAS by making a tarball, but "tar -cSf ..." quits with a "memory exhausted" error after gigabyte 62. My Linux machine has a gigabyte of RAM and a gigabyte of swap space.

(edit) I tried it again about where tar gave up and tar quickly gave up again, so it looks like it may be having trouble dealing with a special file.

This data is surprisingly resistant to being backed up. rsync is 4 times slower than tar because the NAS isn't very fast and it quits in the middle with 'connection reset by peer'; 'cp' doesn't work well on the cifs share because it can't create the special files. Is there a better way?

It takes forever to back up. Before we can trust btrfs or ZFS to backup incremental snapshots, wouldn't it be nice if there was a daemon that used inotify to keep track of which files had actually changed so backups would run more quickly? Where is this program?

How do I backup my Linux box without having to crawl the whole filesystem every time? I would like a program that would detect the new or changed photos, source code, etc. and queue them to be copied over to my NAS.

Will I benefit from the 32-bit PAE-enabled Linux kernel over the 32-bit non-PAE kernel in a server that has exactly 4GB of ram (and 'pae' in the cpuid flags)? Will the system be able to use all 4GB of ram without a PAE kernel, or will some of the memory go idle?