• Spamhaus
• Passive Spam Block List (PSBL
• Spam and Open Relay Blocking System (SORBS)
• Swiss Network Operators Group (SwiNOG)
• SpamCop Blocking List

I configured Sendmail to use those blacklists by putting the following lines in /etc/mail/sendmail.mc:

FEATURE(`blacklist_recipients')dnl
FEATURE(`dnsbl', `sbl.spamhaus.org', `550 Spam Block: mail from $&{client_addr} refused - See http://www.spamhaus.org/sbl/')dnl
FEATURE(`dnsbl', `psbl.surriel.com', `550 Spam Block: mail from $&{client_addr} refused - see http://psbl.surriel.com/')dnl
FEATURE(`dnsbl',`dnsbl.sorbs.net',`550 Spam Block: mail from $&{client_addr} refused - see http://dnsbl.sorbs.net/')dnl
FEATURE(`dnsbl',`dnsrbl.swinog.ch',`550 Spam Block: mail from $&{client_addr} refused - see http://antispam.imp.ch/spamikaze/remove.php')dnl
FEATURE(`enhdnsbl', `bl.spamcop.net', `"Spam blocked see: http://spamcop.net/bl.shtml?"$&{client_addr}', `t')dnl

If you add those lines to the Sendmail configuration file, you need to regenerate /etc/mail/sendmail.cf with the command m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf. Then restart sendmail with service sendmail restart.

Still, despite those multiple anti-spam blacklists, a lot of spam is getting through to accounts on the mail server. So I decided to install Free Antispam for Mail Servers (FRAMS) from Bitdefender, which describes the software thusly:

Bitdefender Free Antispam for Mail Servers provides essential features for increased productivity in any organization by blocking spam on Linux-based mail servers. Bitdefender's award winning antispam engines provide antiphishing, content and attachment filtering. It's extremely easy to install and administrators have an easy to use web-based interface and powerful command line management.

[ More Info ]

[/network/email/sendmail] permanent link

[/os/windows/win7] permanent link

# yum install rdesktop
Loaded plugins: fastestmirror, langpacks
Existing lock /var/run/yum.pid: another copy is running as pid 16020.
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: PackageKit
    Memory :  46 M RSS (1.4 GB VSZ)
    Started: Fri Jul 29 12:08:28 2016 - 01:14 ago
    State  : Running, pid: 16020
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: PackageKit
    Memory :  46 M RSS (1.4 GB VSZ)
    Started: Fri Jul 29 12:08:28 2016 - 01:16 ago
    State  : Sleeping, pid: 16020
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: PackageKit
    Memory :  46 M RSS (1.4 GB VSZ)
    Started: Fri Jul 29 12:08:28 2016 - 01:18 ago
    State  : Sleeping, pid: 16020
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: PackageKit
    Memory :  46 M RSS (1.4 GB VSZ)
    Started: Fri Jul 29 12:08:28 2016 - 01:20 ago
    State  : Sleeping, pid: 16020
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: PackageKit
    Memory :  46 M RSS (1.4 GB VSZ)
    Started: Fri Jul 29 12:08:28 2016 - 01:22 ago
    State  : Sleeping, pid: 16020
Another app is currently holding the yum lock; waiting for it to exit...
  The other application is: PackageKit
    Memory :  46 M RSS (1.4 GB VSZ)
    Started: Fri Jul 29 12:08:28 2016 - 01:24 ago
    State  : Sleeping, pid: 16020
^C

Exiting on user cancel.
#

I checked the process and saw the following information:

# ps aux | grep yum
root     16020 28.4  2.3 1455028 79512 ?       SN   12:08   1:16 /usr/bin/python /usr/share/PackageKit/helpers/yum/yumBackend.py refresh-cache yes
root     16354  0.0  0.0 112652   952 pts/0    S+   12:12   0:00 grep --color=auto yum
#

[ More Info ]

[/os/unix/linux/utilities/package] permanent link

You can determine if the application is already installed using the which command.

$ which gimp
/bin/gimp
$

If it isn't installed, on systems that use the yum package management tool, such as CentOS, you can use the command yum install gimp from the root account to install it. On Linux distributions that use the Advanced Packaging Tool (APT) for package management, e.g., Ubuntu, you can use sudo apt-get install gimp.

To take a snapshot of a window or an area of the screen, take the following steps:

1. Click on File.
2. Click on Create.
3. Select Screenshot.
4. You can then select from the following:
   • Take a screenshot of a single window
   • Take a screenshot of the entire screen
   • Select a region to grab

[ More Info ]

[/software/graphics/gimp] permanent link

# mailq
/var/spool/mqueue is empty
		Total requests: 0
#

I tried sending a test message from the mail sever to an external email account with the mailx command. For the body of the message, I put some text into a file named test.txt and used the < character to provide the contents of the file as input to mailx for the body of the message. I didn't receive any error message and I didn't see any messages stuck in the mail queue when I checked it after I sent the message. But the message was not received at the destination email account.

# mailx -s "Testing" moonpoint@example.com <test.txt
# mailq
/var/spool/mqueue is empty
		Total requests: 0
#

So I then used the sendmail command, instead, to send a test message to see if it would provide me with any information that I could use for troubleshooting the problem. I created a file with the following contents to send as a test message.

# cat temp.txt
Subject: Sendmail test

This is a test.
This is only a test.

You can send a test message whose contents are contained in a text file from a command line interface using a sendmail command in the form sendmail recipient_email_address < input_file. But when I did that, I saw a "Connection refused by [127.0.0.1]" message.

[ More Info ]

[/network/email/sendmail] permanent link

1. cellpadding attribute
2. frameborder attribute on the iframe element
3. scrolling attribute on the iframe element
4. name attribute
5. valign attribute
6. tt element

[/network/web/html/css] permanent link

[/network/web/browser/firefox] permanent link

I verified that I could connect to the email server on the SMTP port, port 25, and the POP3 port, port 110, from external systems and she told me that her husband's system was able to check his email successfully. Since I knew his system was establishing a POP3 connection to the mail server to check email, but her system was establishing an encrypted POP3S connection on port 995, I checked the Linux email server to verify that it was listening for connections on port 995, since there had been a power outage at its location recently that I thought might have caused it to reboot. It was listening on that port.

$ netstat -a | grep -i pop3s
tcp        0      0 0.0.0.0:pop3s           0.0.0.0:*               LISTEN     
tcp6       0      0 [::]:pop3s              [::]:*                  LISTEN

So I thought the problem was likely at a NetScreen firewall between the user and the server. I logged into the firewall via Secure Shell (SSH). I verified that there were no filters currently set for the firewall and then set a filter for destination port 995 with the command set ffilter dst-port 995. I then cleared the debug buffer with clear db and started debugging on the router/firewall with debug flow basic - see NetScreen Debugging Commands for an explanation of the debugging commands. I could see that TCP packets were reaching the firewall, but the firewall was reporting "packet dropped: for self but not interested".

[ More Info ]

[/security/firewalls/netscreen] permanent link

$ diskutil list
/dev/disk0
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.3 GB   disk0
   1:                        EFI EFI                     209.7 MB   disk0s1
   2:                  Apple_HFS Macintosh HD            499.4 GB   disk0s2
   3:                 Apple_Boot Recovery HD             650.0 MB   disk0s3
/dev/disk2
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *13.8 MB    disk2
   1:                  Apple_HFS C_PGP2FV_B_A0           13.8 MB    disk2s1
/dev/disk3
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:      GUID_partition_scheme                        *500.1 GB   disk3
   1:                        EFI EFI                     209.7 MB   disk3s1
   2:                  Apple_HFS TOSHIBA EXT             499.8 GB   disk3s2
   3:                 Apple_Boot Boot OS X               134.2 MB   disk3s3
$

[ More Info ]

[/os/os-x] permanent link

$ ncal
    July 2016
Mo     4 11 18 25
Tu     5 12 19 26
We     6 13 20 27
Th     7 14 21 28
Fr  1  8 15 22 29
Sa  2  9 16 23 30
Su  3 10 17 24 31

If you wish to display the calendar for another month, you can specify the month on the command line by putting the month and year after the command. E.g., to display a calendar for February of 20216, the command below could be used. The command ncal february 2016 would also work.

$ ncal 2 2016
    February 2016
Mo  1  8 15 22 29
Tu  2  9 16 23
We  3 10 17 24
Th  4 11 18 25
Fr  5 12 19 26
Sa  6 13 20 27
Su  7 14 21 28

[ More Info ]

[/os/os-x] permanent link

$ pgrep Safari
51313
78209
95848
95874

If you wish to see the newest, i.e., the most recently started one, of those processes, you can use the -n option.

$ pgrep -n Safari
95874

You can use the -l option to viewer longer information on the processes, i.e, process names as well as PIDs.

$ pgrep -l Safari
51313 Safari
78209 SafariNotificat
95848 com.apple.Safar
95874 com.apple.Safar

If you combine the -l option with the -f option, you will see even more information for the process that may be helpful when the process name is truncated.

$ pgrep -lfn Safari
95874 /System/Library/PrivateFrameworks/SafariServices.framework/Versions/A/XPCS
ervices/com.apple.SafariServices.xpc/Contents/MacOS/com.apple.SafariServices

[/os/os-x] permanent link

• Open Disk Utility, from the Applications/Utilities directory.
• Click on the external disk drive in the left pane of the utility to select it.
• Click on File, then select New and Disk Image from, e.g. Disk Image from "TOSHIBA EXT" for an external Toshiba USB drive.
• You will then be prompted to give the image a name and can select the directory where you wish it to be stored. You can also select whether the image will be compressed and whether it will be encrypted.
• Click on Save to initiate the creation of the disk image. When prompted that "diskimages-helper wants to make changes. Type your password to allow this.", provide a password for an account with administrator privileges on the system. When the image has been created, you will see it listed in the left pane of the Disk Utility window.

You can then use the OS X Finder program to view the files stored in the Apple Disk Image DMG file that was created by double-clicking on the .dmg file that was created.

[ More Info ]

[/os/os-x] permanent link

When I then searched online for that number, I found others reporting receiving similar scam calls from that number, e.g., at the 800Notes page at 315-825-8947 I found reports such as "They called me 4 times. I finally picked up on the last time and it was a woman with an Indian accent claiming to be from Windows Tech Support and I immediately hung up. This is a scam."

Fifty minutes later, my wife received a similar call again at 1:52 PM from someone with an Indian accent. She informed the caller that she knew it was a scam and asked to be removed from the calling list. I used *69 again and this time I was informed that the caling number was 315-639-8222. I found that number also listed at the 800Notes site at 315-639-8222. When I tried calling that number I heard a message that "The number you have reached has been disconnected or is no longer in service."

We received two more "Windows Technical Departement" calls within a couple of hours. We were watching a series on Netflix during that period and I didn't try to check those two calling numbers with *69.

I think it was the second call where I again picked up the phone and talked to the caller who again had an Indian accent - my wife told me all four seemed to have an Indian accent. I asked where he was calling from and he told me New York. I asked him what company he worked for; he said "Windows Technical Department". I asked him if he knew what company produces Windows. He didn't answer, but attempted to continue with his spiel telling me where to click with the mouse. I tried to see if he knew anything except the spiel he had been given, but this caller wanted to stick with the spiel telling me where to click, though he eventually hung up when I told him to hold on for a minute while I went to another phone, where I was going to record our conversation.

My wife gets very annoyed by such calls; she's usually the one picking up the phone for our home phone number, which is a VoIP service from our cable provider. I haven't received such scam calls on my cell phone number, though I do get a fair number of unwanted telemarketing calls on that number, often from spoofed numbers. My wife said she frequently gets the Windows scam calls when I'm not home. A few months ago, I received a call on our home number from another scammer pretending to be from the IRS.

Our phone numbers are on the U.S. Federal Trade Commission (FTC) Do Not Call list, but, of course, scammers, and many telemarketers as well, don't bother checking that list.

Coincidentally, today I read an article on the Ars Technica site titled Mobile carriers aren’t doing enough to fight robocalls, senators say. I wasn't pleased by the following paragraph in that article:

AT&T CEO Randall Stephenson recently claimed that AT&T doesn't have the "authority" to implement new robocall blocking technology in its mobile network, even though the Federal Communications Commission clearly stated last year that carriers have the "green light" to offer robocall-blocking services to consumers.

[/security/scams] permanent link

If you specify the -n or --noop option, information on the device will be shown, but no action is taken.

$ eject -n
eject: device is `/dev/sr0'

You can use eject --default to see the default name for the device.

$ eject --default
eject: default device: `/dev/cdrom'

[ More Info ]

[/os/unix/linux/centos] permanent link

$ uptime
22:17  up 20 days, 12:24, 18 users, load averages: 2.95 2.93 2.46
$

The output above shows that the time is 10:17 PM (the time is in 24-hour clock format, often referred to as military time) and that it has been 20 days, 12 hours, and 24 minutes since the system was last rebooted. The three numbers at the end of the output, 2.95, 2.93, and 2.46, are the load average of the system over the last 1, 5, and 15 minutes.

The output above shows 18 users on the system when the uptime command was run. If you want to see a list of those users, use the w command. If you are the only user of the system, don't worry that you may see a number greater than 1 listed; it's likely they are all logins for your account as they were when I checked for the above instance where "18 users" was listed. The output is showing every logged in session and in this case I had multiple shell prompts through open tabs in the Terminal application.

[/os/os-x] permanent link

[ More Info ]

[/languages/python] permanent link

When I used the airport utility from a Terminal windowto check the noise level and signal strength for the WiFi connection, I saw the following:

$ /System/Library/PrivateFrameworks/Apple80211.framework/Versions/Current/Resources/airport -I
     agrCtlRSSI: -56
     agrExtRSSI: 0
    agrCtlNoise: -87
    agrExtNoise: 0
          state: running
        op mode: station 
     lastTxRate: 73
        maxRate: 72
lastAssocStatus: 0
    802.11 auth: open
      link auth: wpa2-psk
          BSSID: 94:44:52:4a:43:40
           SSID: Rain
            MCS: 7
        channel: 11

[ More Info ]

[/os/os-x/wireless] permanent link

I had closed and reopened Safari after it stopped responding to any keyboard entries or mouse movement.

When I clicked on Safari from Safari's menu bar and chose Preferences and then clicked on Extensions, no extensions were shown. I noticed that the Develop option was not appearing in the Safari menu bar, though I had enabled the Develop menu. So I re-enabled the Develop menu by clicking on Safari from the Safari menu bar, selecting Preferences, then clicking on Advanced and then checking the check box next to "Show Develop menu in menu bar". I then clicked on Develop from the menu bar when that option reappeared. I then selected Disable Extensions. I then clicked on Develop again and again selected Disable Extensions, which this time removed the check mark next to that option.

[ More Info ]

[/network/web/browser/safari] permanent link

Batch File

@echo off
echo Set oWMP = CreateObject("WMPlayer.OCX.7")  >> %temp%\temp.vbs
echo Set colCDROMs = oWMP.cdromCollection       >> %temp%\temp.vbs
echo For i = 0 to colCDROMs.Count-1             >> %temp%\temp.vbs
echo colCDROMs.Item(i).Eject                    >> %temp%\temp.vbs
echo next                                       >> %temp%\temp.vbs
echo oWMP.close                                 >> %temp%\temp.vbs
%temp%\temp.vbs
timeout /t 1
del %temp%\temp.vbs

[ More Info ]

[/os/windows/utilities] permanent link

ns5gt-> get clock
Date 06/24/1997 07:43:02, Daylight Saving Time enabled
The Network Time Protocol is Disabled
Up 917 hours 27 minutes 27 seconds Since 17 May 1997 02:15:35
867138182.710668 seconds since 1/1/1970 0:0:0 GMT
GMT time zone area -5:00
GMT time zone offset 4:00
ns5gt->

In the above output, I can see that the date and time are not set correctly. I can see that the time offset from Greenwich Mean Time (GMT) is four hours, which is currently correct for this device, though. You can see the current GMT time as well as the times for many major cities throughout the world at The World Clock - Worldwide.

The set clock command can be used to set the date.

ns5gt-> set clock ?
mm/dd/yyyy           month/day/year
dst-off              disable daylight saving time
ntp                  enable network time protocol
timezone             GMT Time zone area
ns5gt->

You can specify the month, date, and year in the form mm/dd/yyyy . The time should be specified after the date in the form hh:mm or hh:mm:ss.

[ More Info ]

[/security/firewalls/netscreen] permanent link

$ ls ~/Library/Application\ Support/Firefox/Profiles
bgq13udo.default
$

Within that directory is a places.sqlite SQLite database. OS X comes with the sqlite3 program for creating, viewing, and editing SQLite databases - see Using SQLite for information on how to use the program.

[ More Info ]

[/network/web/browser/firefox] permanent link

However, you can configure Safari to show details on cookies that are placed on the system when you visit a webpage by taking the following steps within the Safari browser.

[ More Info ]

[/network/web/browser/safari] permanent link

# telnet 127.0.0.1 110
Trying 127.0.0.1...
Connected to 127.0.0.1.
Escape character is '^]'.
user nell
Connection closed by foreign host.
#

So I then checked Dovecot's log file. I saw many entries similar to the following ones in that file:

# grep dovecot /var/log/maillog | tail -5
Jul  4 09:15:44 moonpoint dovecot: master: Warning: service(pop3-login): process
_limit (100) reached, client connections are being dropped
Jul  4 09:18:55 moonpoint dovecot: master: Warning: service(pop3-login): process
_limit (100) reached, client connections are being dropped
Jul  4 09:19:57 moonpoint dovecot: master: Warning: service(pop3-login): process
_limit (100) reached, client connections are being dropped
Jul  4 09:21:01 moonpoint dovecot: master: Warning: service(pop3-login): process
_limit (100) reached, client connections are being dropped
Jul  4 09:26:13 moonpoint dovecot: master: Warning: service(pop3-login): process
_limit (100) reached, client connections are being dropped
#

[ More Info ]

[/network/email/dovecot] permanent link

To generate random numbers at the command line, you can open a command prompt window and type echo %random%.

c:\Users\Public\Documents>echo %random%
31090

c:\Users\Public\Documents>echo %random%
16802

c:\Users\Public\Documents>echo %random%
20253

c:\Users\Public\Documents>

When you use %random%, you will get numbers between 0 and 32,767, which is 2 to the 15^th power. But you can make the range of numbers smaller by using a command like the following where 0 is the lower bound for the numbers and n-1 is the upper bound of the range.

SET /a _rand=(%RANDOM%*n/32768)

[ More Info ]

[/os/windows] permanent link

[ More Info ]

[/network/ssh] permanent link

C:\>nslookup
Default Server:
Address:  192.168.0.1

> 66.235.139.18
Server:
Address:  192.168.0.1

Name:    *.112.2o7.net
Address:  66.235.139.18

>

When I put http://2o7.net in the address bar of a browser, I was taken to a Adobe Marketing Cloud privacy web page, which states:

The Adobe Marketing Cloud solutions enable our business customers to personalize and improve the performance of their websites, apps, and social networking pages. These companies use Adobe Marketing Cloud solutions to collect and analyze information, such as clicks made by visitors on their websites, apps, and social networking pages. The solutions also allow the companies to provide you with more relevant messages within their emails, text messages, and other online and offline marketing campaigns. In general, companies use Adobe Marketing Cloud solutions when they want to better understand and improve their online resources and marketing.

[ More Info ]

[/network/Internet/domains] permanent link