Unable to update rkhunter

Today when I ran the command (which I run every day and all is well):

sudo rkhunter --update

In order to check for updates to database files I got this error every time:

[ Rootkit Hunter version 1.4.2 ]

Checking rkhunter data files...
  Checking file mirrors.dat                                  [ Update failed ]
  Checking file programs_bad.dat                             [ Update failed ]

  Checking file backdoorports.dat                            [ Update failed ]
  Checking file suspscan.dat                                 [ Update failed ]
  Checking file i18n versions                                [ Update failed ]

Please check the log file (/var/log/rkhunter.log)

So I checked the log file and this was its contents:

[11:52:57] Checking rkhunter data files...

[11:52:57] Info: Created temporary file '/var/lib/rkhunter/tmp/rkhunter.upd.5ztlaw3od5'
[11:52:57] Info: Created temporary file '/var/lib/rkhunter/tmp/mirrors.dat.9HiKnqrCFB'
[11:52:57] Info: The mirrors file has been rotated: /var/lib/rkhunter/db/mirrors.dat
[11:52:57] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.5ztlaw3od5" http://rkhunter.sourceforge.net/1.3/mirrors.dat 2>/dev/null'
[11:52:57] Warning: Download of 'mirrors.dat' failed: Unable to determine the latest version number.
[11:52:57] Checking file mirrors.dat                         [ Update failed ]
[11:52:57] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.5ztlaw3od5" http://rkhunter.sourceforge.net/1.3/programs_bad.dat 2>/dev/null'
[11:52:58] Warning: Download of 'programs_bad.dat' failed: Unable to determine the latest version number.
[11:52:58] Checking file programs_bad.dat                    [ Update failed ]
[11:52:58] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.5ztlaw3od5" http://rkhunter.sourceforge.net/1.3/backdoorports.dat 2>/dev/null'

[11:52:58] Warning: Download of 'backdoorports.dat' failed: Unable to determine the latest version number.
[11:52:58] Checking file backdoorports.dat                   [ Update failed ]
[11:52:58] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.5ztlaw3od5" http://rkhunter.sourceforge.net/1.3/suspscan.dat 2>/dev/null'
[11:52:58] Warning: Download of 'suspscan.dat' failed: Unable to determine the latest version number.
[11:52:58] Checking file suspscan.dat                        [ Update failed ]
[11:52:58] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.5ztlaw3od5" http://rkhunter.sourceforge.net/1.3/i18n/1.4.2/i18n.ver 2>/dev/null'
[11:52:59] Checking file i18n versions                       [ Update failed ]
[11:52:59] Warning: Download of 'i18n.ver' failed: Unable to determine the latest version number.
[11:52:59]
[11:52:59] Info: End date is Fri Jul 17 11:52:59 BST 2015

When running this command:

sudo rkhunter --versioncheck

I also get a similar error:

[ Rootkit Hunter version 1.4.2 ]


Checking rkhunter version...
  This version  : 1.4.2
  Latest version: Download failed

Why is this? And how can I fix it? Or is it not something my end? In which case, what should I do?

---

OS Information:

Description:    Ubuntu 15.04
Release:    15.04

Package Information:

rkhunter:
  Installed: 1.4.2-0.4

  Candidate: 1.4.2-0.4
  Version table:
 *** 1.4.2-0.4 0
        500 http://gb.archive.ubuntu.com/ubuntu/ vivid/universe amd64 Packages
        100 /var/lib/dpkg/status

TL;DR The sourceforge.net website is temporarily in static offline mode for some projects.

Therefore, do nothing and try it again later ;)

---

After checking my logfile

[13:12:22] Checking rkhunter data files...
[13:12:22] Info: Created temporary file '/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6'
[13:12:22] Info: Created temporary file '/var/lib/rkhunter/tmp/mirrors.dat.SZ4xQZhnLE'
[13:12:22] Info: The mirrors file has been rotated: /var/lib/rkhunter/db/mirrors.dat
[13:12:22] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/mirrors.dat 2>/dev/null'

[13:12:22] Info: Download failed - 1 mirror(s) left.
[13:12:23] Info: Created temporary file '/var/lib/rkhunter/tmp/mirrors.dat.XOvMxBABzh'
[13:12:23] Info: The mirrors file has been rotated: /var/lib/rkhunter/db/mirrors.dat
[13:12:23] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/mirrors.dat 2>/dev/null'
[13:12:23] Warning: Download of 'mirrors.dat' failed: Unable to determine the latest version number.
[13:12:23] Checking file mirrors.dat                         [ Update failed ]
[13:12:23] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/programs_bad.dat 2>/dev/null'
[13:12:23] Warning: Download of 'programs_bad.dat' failed: Unable to determine the latest version number.
[13:12:23] Checking file programs_bad.dat                    [ Update failed ]
[13:12:23] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/backdoorports.dat 2>/dev/null'

[13:12:24] Warning: Download of 'backdoorports.dat' failed: Unable to determine the latest version number.
[13:12:24] Checking file backdoorports.dat                   [ Update failed ]
[13:12:24] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/suspscan.dat 2>/dev/null'
[13:12:24] Warning: Download of 'suspscan.dat' failed: Unable to determine the latest version number.
[13:12:24] Checking file suspscan.dat                        [ Update failed ]
[13:12:24] Info: Executing download command '/usr/bin/wget  -q -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/i18n/1.4.2/i18n.ver 2>/dev/null'
[13:12:24] Checking file i18n versions                       [ Update failed ]
[13:12:24] Warning: Download of 'i18n.ver' failed: Unable to determine the latest version number.

I tried:

sudo /usr/bin/wget  -O "/var/lib/rkhunter/tmp/rkhunter.upd.UndVYmZ4q6" http://rkhunter.sourceforge.net/1.3/mirrors.dat

with the result

--2015-07-17 13:13:34--  http://rkhunter.sourceforge.net/1.3/mirrors.dat
Resolving rkhunter.sourceforge.net (rkhunter.sourceforge.net)... 216.34.181.96
Connecting to rkhunter.sourceforge.net (rkhunter.sourceforge.net)|216.34.181.96|:80... connected.

HTTP request sent, awaiting response... 503 Service Unavailable
2015-07-17 13:13:34 ERROR 503: Service Unavailable.

Now let's check http://rkhunter.sourceforge.net/1.3/mirrors.dat

The sourceforge.net website is temporarily in static offline mode.
Only a very limited set of project pages are available until the main website returns to service.