Questions and Answers

Amy Rich

Q Our mail hub is a FreeBSD 4.5-STABLE box running Postfix. We were recently the target of a large-scale spam attack. There are still a lot of undeliverable bogus messages sitting in the queue (no valid user, and no valid bounce address). I want to remove all of these bogus files, but I'm not certain whether I can actually just rm the files while the mail server is running, or whether I must shut it down and remove the spooled messages with some other program. Any clues?

A Recent versions of Postfix include an option to the postsuper command to clean out queued messages by queue ID. To delete a message with a queue ID of ABCDEF, for example, you would do:

postsuper -d ABCDEF

postsuper -d - < file

http://www.postfix.org/faq.html#deleting)

• The Postfix queue manager deletes the file that postsuper was supposed to delete, because Postfix was finished with the message.
• New mail arrives, and the new message is given the same queue ID as the message that postsuper was supposed to delete. The probability for reusing a deleted queue ID is about 1 in 2^15 (the number of different microsecond values that the system clock can distinguish).
• postsuper deletes the new message file, instead of the old file that should have been deleted.

A It sounds as if you've corrupted your Jumpstart boot image. When you were redoing your packages, did you happen to export your Jumpstart boot image read write and then try to jump your machine? If so, you probably overwrote files in the boot image that used to be symbolic links to /tmp during the boot process. To be absolutely sure that you correct all of the corrupted parts of the image, you should recreate your boot image from an original ISO image with the setup_install_server script. If you want to just try to repair your image, the following files in $CDROM_DIR/Solaris_8/Tools/Boot/ should be symbolic links instead of real files:

etc/default/init -> ../../tmp/root/etc/default/init
etc/defaultdomain -> ../tmp/root/etc/defaultdomain
etc/defaultrouter -> ../tmp/root/etc/defaultrouter
etc/device.tab -> ../tmp/root/etc/device.tab
etc/dgroup.tab -> ../tmp/root/etc/dgroup.tab
etc/format.dat -> ../tmp/root/etc/format.dat
etc/inet/hosts -> ../../tmp/root/etc/inet/hosts
etc/inet/netmasks -> ../../tmp/root/etc/inet/netmasks
etc/instance -> ../tmp/root/etc/instance
etc/krb5/krb5.conf -> ../../tmp/root/etc/krb5/krb5.conf
etc/net/ticlts/hosts -> ../../../tmp/root/etc/net/ticlts/hosts
etc/net/ticots/hosts -> ../../../tmp/root/etc/net/ticots/hosts
etc/net/ticotsord/hosts -> ../../../tmp/root/etc/net/ticotsord/hosts
etc/nodename -> ../tmp/root/etc/nodename
etc/nsswitch.conf -> ../tmp/root/etc/nsswitch.conf
etc/ps_data -> ../tmp/root/etc/ps_data
etc/resolv.conf -> ../tmp/root/etc/resolv.conf
etc/sysidcfg -> ../tmp/root/etc/sysidcfg
etc/transfer_list -> ../tmp/root/etc/transfer_list
etc/vfstab -> ../tmp/root/etc/vfstab
etc/.mnt.lock -> ../tmp/root/etc/.mnt.lock
etc/.name_service_door -> ../tmp/root/etc/.name_service_door
etc/.sysIDtool.state -> ../tmp/root/etc/.sysIDtool.state
var -> ./tmp/root/var/
.tmp_proto/kernel -> ../tmp/root/kernel

#path_to_inst_bootstrap_1

Q I was trying to compile OpenSSH on my OpenBSD machine, but I keep getting the following error:

- -L. -Lopenbsd-compat/  -L/usr/local/lib -R/usr/local/lib -lssh -lopenbsd-compat -lz -lsocket -lnsl  -lcrypto
Undefined                       first referenced
 symbol                             in file
__inet_ntoa                         ./libssh.a(channels.o)
__inet_ntop                         sshconnect.o
ld: fatal: Symbol referencing errors. No output written to ssh
collect2: ld returned 1 exit status
*** Error code 1

gcc -o ssh ssh.o sshconnect.o sshconnect1.o sshconnect2.o sshtty.o 
  readconf.o clientloop.o -L. -Lopenbsd-compat/ -L/usr/local/lib \
  -R/usr/local/lib -lssh -l openbsd-compat -lz -lsocket -lnsl \
  -lcrypto  -lresolv
Undefined                       first referenced
 symbol                             in file
__inet_ntoa                         ./libssh.a(channels.o)
__inet_ntop                         sshconnect.o
ld: fatal: Symbol referencing errors. No output written to ssh
collect2: ld returned 1 exit status
*** Error code 1

A This looks like you have installed your own version of bind, and gcc is picking up the "new" include files first. Try compiling with -lbind, if you have a /usr/local/lib/libbind.a, or try fixing your bind installation so that gcc does not pick up the conflicting include files first.

Q We have a Graphite series Apple Airport that handles the 802.11b bridging at work. The clients are two FreeBSD 4.5-STABLE laptops with Lucent gold cards. The Airport was also upgraded to a gold card, so we could do 128-bit WEP, when it was purchased (before it was discovered that WEP was broken).

We recently moved offices and reinstalled the two laptops. Now, with no discernible pattern, we're seeing very odd behavior on our wireless LAN. Everything will be working just fine, and then the laptops will be unable to talk to anything, including each other and the Airport. The LEDs on the laptop Lucent cards look normal, though, and the lights on the Airport also look normal. The wired LAN can still talk to the Airport when this happens. If we put the laptops into ad hoc mode, they can talk just fine, but they obviously can't talk with the wired network at that point. This also breaks DHCP, which is used to feed the laptops much of their network configuration information, including the IP.

We aren't sure if we accidentally did something to the Airport, the laptop configuration, or what. Any insight you have would be appreciated.

your airport's ethernet address

LANNetworkName

plaintext WEP key

airport.host.name

A Since you made several changes at once, that's going to make it harder to track down the issue:

• Because the wired side can still talk to the airport, I would guess it's not a physical wiring issue in your new building. If you haven't already done so, you may want to test all of the wires, anyway, for future sanity.
• Since the laptops can talk to each other in ad hoc mode, it's probably not the gold card in either laptop. It's also unlikely that it's your laptop configuration, since it works some of the time. Just in case, however, I'll go over what should be in your config files.
• It's unlikely that it's the Airport configuration, since, again, you said it works some of the time. You can redo the Airport configuration to be sure, and you may also want to reset the Airport and upgrade the firmware while you're at it.
• The wireless card in your Airport could be failing. The best way to test this is to swap cards with a known working card, perhaps from one of the laptops.
• Your Airport could be failing. There are known hardware issues with certain serial number ranges of Graphite Airports.

Laptop configuration:

The laptop configuration is fairly simple. It can be completely done in /etc/pccard.conf, or you can split it into /etc/pccard.conf and /etc/dhclient-exit-hooks. I prefer the latter solution, because it allows you to move between multiple networks without having to manually reset your configuration. /etc/pccard.conf should have the following entry:

# Lucent WaveLAN/IEEE
card "Lucent Technologies" "WaveLAN/IEEE"
   config  0x1 "wi0" ?
   insert  logger -t pccard:$device -s WaveLAN/IEEE inserted
   insert  /etc/pccard_ether $device
   remove  logger -t pccard:$device -s WaveLAN/IEEE removed
   remove  /sbin/ifconfig $device delete

your airport's ethernet address

LANNetworkName

plaintext WEP key

airport.host.name

#!/bin/sh -x

# Read the BSS ID and network name
get_wireless_bss()
{
        bssid=cmd | awk '$1 == "Current" && $2 == "BSSID:" { print $4 }'
     bssnet=cmd | awk '$1 == "Current" && $2 == "netname" { print $5 }'}

# Try to identify and configure for the wireless net
find_wireless_net()
{
        if [ "$bssid" = "your airport's ethernet address" ]
        then
                # On the work LAN
                $cmd -e 1
                $cmd -n LANNetworkName
                $cmd -k 'plaintext WEP key'
        elif [ "$bssnet" = "LANNetworkName" ]
        then
                # On the work LAN
                $cmd -e 1
                $cmd -n LANNetworkName
                $cmd -k 'plaintext WEP key'

        else
                # unknown net, turn off encryption
                $cmd -e 0
                $cmd -n ''
        fi
}

# Initialize the WaveLAN card with the proper parameters
if [ "$interface" = "wi0" -a "$reason" = "PREINIT" ]
then
        cmd="/usr/sbin/wicontrol -i $interface"
        $cmd -P 0 # turn off powersave mode for better throughput
        $cmd -s airport.host.name

        get_wireless_bss
        if [ "$bssid" = "44:44:44:44:44:44" ]
        then
                # Unknown, try known networks
                $cmd -e 1
                for net in LANNetworkName
                do
                        $cmd -n $net
                        sleep 1
                        get_wireless_bss
                        if [ "$bssid" != "44:44:44:44:44:44" ]
                        then
                                break
                        fi
                done
        fi
        find_wireless_net
fi
exit 0

/usr/sbin/wicontrol -i wi0

Airport configuration:

You can configure the Airport from pretty much any kind of machine these days. If you're using a 128-bit WEP key, though, be sure that you find software that supports it. I know people who've had good luck with Windows clients using Freebase (http://freebase.sourceforge.net/) and some who have used the Java-based configurator v1.5 on UNIX hosts (http://edge.mcs.drexel.edu/GICL/people/sevy/airport/).

If you have a tool that will let you upload new firmware, you may also want to completely reset the Airport (hold in the reset switch within a few seconds of turning on the Airport. The right light should flash amber when the Airport has been reset). Prior to 1.3, Apple's Airport firmware was supplied as a standalone file as part of a software download bundled into a smi archive file. However, with the 1.3 release, the firmware is now embedded within the base station admin utility. It's possible to extract the firmware image using ResEdit, or you can grab a copy from firmware (http://www.icir.org/fenner/airport/).

Airport failure:

There is a recall on Apple Airport base stations with the serial number range PW940... to PW952... These Airports had a tendency to blow their capacitors, resulting in the constant reset of the station. I've also seen the stations fail slowly with the symptoms you describe. Perhaps your Airport received a power surge that damaged one or more of the capacitors. Take a look at http://www.vonwentzel.net/ABS/Repair.html for a list of symptoms, hardware fixes, and information on the recall from Apple.

Q I'm starting to enter the world of writing GUI Perl applications. Are there any good Perl/GUI application development tools out there, preferably something where I can do drag and drop programming?

A Most GUI applications that you're going to write in Perl will probably be integrated with Tk. Take a look at O'Reilly's Mastering Perl/Tk book:

http://www.oreilly.com/catalog/mastperltk/

http://www.perltk.org/

http://w4.lns.cornell.edu/~pvhp/ptk/ptkFAQ.html

http://www.perl.com/cs/user/query/q/6?id_topic=75

http://guido.sourceforge.net/

http://spectcl.sourceforge.net/