If you run a mail server with sendmail, and a user wants to forward his mail to another server, one way is /etc/mail/virtusertable:

joe@example.com         joe@gmail.com

As you probably know, the sender address of most spam mails belongs to someone - not the spammer of course. If you refuse to accept a spam email, you must never send back an error email to the alleged sender address. Otherwise, you have become a source of unsolicited email yourself.

When in our example, gmail.com does not accept an email, your server will send an error mail to the alleged sender address.

If you watch your postmaster mailbox, you will notice this every time the alleged sender address is invalid. You might be tempted to suppress these postmaster notifications with

define(`confDOUBLE_BOUNCE_ADDRESS', `')dnl

But this only supresses the double bounces. If the sender address is valid, someone will get an error email about spam he didn't send.

The solution is to not use virtusertable for external forwarding, but instead do it in /home/joe/.procmailrc:

:0
* ^From: Mail Delivery Subsystem <MAILER-DAEMON@example.com>
* ^To: <joe@example.com>
bounced-mails

:0
! joe@gmail.com 

In this case, the sender address is set to joe@example.com before the mail is forwarded to gmail.com, and any error messages go back to joe.

Fedora 7 on a Dell D800 requires a little work to get suspend/resume working. The default configuration causes it to freeze during the resume, with the shift and scroll lock LEDs blinking.

The following has been tested with kernel-2.6.22.9-91.fc7 and NVIDIA-Linux-x86-100.14.19 on a Dell Latitude D800 with GeForce FX Go5200 graphics.

1. If you use the binary-only nvidia driver, append "agp=off" to the kernel line in /etc/grub.conf. This disables the built-in AGP driver and allows nvidia to load its own.

   kernel /vmlinuz-2.6.22.9-91.fc7 ro root=/dev/vg1/root quiet agp=off
   

2. Edit /etc/X11/xorg.conf and set the NvAGP option:

   Section "Device"
       ...
       Driver         "nvidia"
       Option         "NvAGP" "1"
   EndSection
   

3. Reboot, log in and check if the nvidia AGP driver is used:

   # cat /proc/driver/nvidia/agp/status
   Status:          Enabled
   Driver:          NVIDIA
   

4. Create /etc/pm/config.d/unload_modules with the following content:

   SUSPEND_MODULES="uhci_hcd"
   

   Create /etc/pm/config.d/nvidia with the following content:

   DISPLAY_QUIRK_VBE_POST=false
   

   Make the files executable with

   chmod +x /etc/pm/config.d/unload_modules /etc/pm/config.d/nvidia
   

Suspend and resume should work now.

After upgrading to Fedora 7, my Vodafone 3G Datacard (the old UMTS PCMCIA adapter) stopped working. Here's what I had to do to make it work again.

Create /etc/udev/rules.d/48-UMTS.rules with the following content:

BUS=="usb", KERNEL=="ttyUSB0", SYSFS{interface}=="Data Interface", SYMLINK+="umts", \
  RUN+="/usr/bin/wvdial --config /etc/wvdial-pin.conf"
BUS=="usb", KERNEL=="ttyUSB2", SYSFS{interface}=="Data Interface", SYMLINK+="gsm"

The wvdial configuration for setting the PIN is stored in /etc/wvdial-pin.conf. Replace "1234" with your own PIN.

Modem = /dev/umts
Baud = 460800
SetVolume = 0
Dial Command = ATDT
FlowControl = NOFLOW
Init1 = ATZ
Init2 = AT+CPIN="1234"

/etc/wvdial.conf contains the settings for establishing an UMTS connection:

[ModemUMTS]
Modem = /dev/umts
Baud = 460800
SetVolume = 0
Dial Command = ATDT
Init1 = ATZ
Init2 = ATM0
Init3 = ATM0
FlowControl = NOFLOW
[Dialer umts]
Username = VFD2
Password = WAP
Phone = *99***1#
Stupid Mode = 1
Init1 = ATZ
Init2 = ATQ0 V1 E1 S0=0 &C1 &D2 +FCLASS=0
Init3 = AT+CGDCONT=1,"IP","web.vodafone.de"
Inherits = ModemUMTS

Next, we need to configure a network interface. Put this into /etc/sysconfig/network-scripts/ifcfg-umts:

IPV6INIT=no
ONBOOT=no
USERCTL=yes
PEERDNS=yes
TYPE=Modem
DEVICE=ppp0
BOOTPROTO=dialup
LINESPEED=460800
MODEMPORT=/dev/umts
IDLETIMEOUT=300
PROVIDER=umts
DEFROUTE=yes
PERSIST=no
WVDIALSECT=umts
MODEMNAME=ModemUMTS
DEMAND=no
PAPNAME=VFD2
AC=off
BSDCOMP=off
VJCCOMP=off
CCP=off
PC=off
VJ=off

This configuration has to be made available at two other locations:

ln /etc/sysconfig/network-scripts/ifcfg-umts \
  /etc/sysconfig/networking/devices/ifcfg-umts
ln /etc/sysconfig/network-scripts/ifcfg-umts \
  /etc/sysconfig/networking/profiles/default/ifcfg-umts

Now, tell PPP about the connection in /etc/ppp/peers/umts:

connect "/usr/bin/wvdial --remotename umts --chat 'umts'"

In /etc/ppp/peers/chap-secrets and pap-secrets, append this line at the end:

"VFD2"  *       "WAP"

SELinux prevents udev from running wvdial, and initialization of the PIN fails. To get around this, create /tmp/udevwvdial.te:

module udevwvdial 1.0;

require {
        type var_lock_t;
        type udev_t;
        class dir { write remove_name add_name };
        class file { write read create unlink };
}

allow udev_t var_lock_t:dir { write remove_name add_name };
allow udev_t var_lock_t:file { write read create unlink };

Compile and load the SELinux module.

checkmodule -M -m -o udevwvdial.mod udevwvdial.te
semodule_package -o udevwvdial.pp -m udevwvdial.mod
semodule -i udevwvdial.pp

The semodule command stores the module in /etc/selinux, so it will stay active when you reboot.

You should now be able to establish a connection with ifup umts and terminate it with ifdown umts. When the card switches between UMTS and GPS, the connection attempt may time out, so retry before checking the configuration files.