I try to install the flash plugin behind a firewall but there is a serious regression
with flashplugin-installer=11.2.202.235ubuntu0.12.04.1 (11.2.202.235ubuntu0.11.10.1 works fine, see below)

Logs:

# apt-get install flashplugin-installer=11.2.202.235ubuntu0.11.10.1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Suggested packages:
  ttf-xfree86-nonfree xfs
The following packages will be DOWNGRADED:
  flashplugin-installer
0 upgraded, 0 newly installed, 1 downgraded, 0 to remove and 0 not upgraded.
Need to get 0 B/8740 B of archives.
After this operation, 32.8 kB disk space will be freed.
Do you want to continue [Y/n]?
Preconfiguring packages ...
dpkg: warning: downgrading flashplugin-installer from 11.2.202.235ubuntu0.12.04.1 to 11.2.202.235ubuntu0.11.10.1.
(Reading database ... 683933 files and directories currently installed.)
Preparing to replace flashplugin-installer 11.2.202.235ubuntu0.12.04.1 (using .../flashplugin-installer_11.2.202.235ubuntu0.11.10.1_i386.deb) ...
Unpacking replacement flashplugin-installer ...
Processing triggers for update-notifier-common ...
Setting up flashplugin-installer (11.2.202.235ubuntu0.11.10.1) ...
Downloading...
--2012-05-15 12:35:38--  http://archive.canonical.com/pool/partner/a/adobe-flashplugin/adobe-flashplugin_11.2.202.235.orig.tar.gz
Connecting to 10.195.111.98:80... connected.
Proxy request sent, awaiting response... 200 OK
Length: 14131146 (13M) [application/x-gzip]
Saving to: `./adobe-flashplugin_11.2.202.235.orig.tar.gz'

     0K ........ ........ ........ ........ ........ ........ 22% 1.68M 6s
  3072K ........ ........ ........ ........ ........ ........ 44% 1.34M 5s
  6144K ........ ........ ........ ........ ........ ........ 66% 1.42M 3s
  9216K ........ ........ ........ ........ ........ ........ 89% 1.56M 1s
 12288K ........ ........ .......                            100% 1.59M=9.0s

2012-05-15 12:35:47 (1.50 MB/s) - `./adobe-flashplugin_11.2.202.235.orig.tar.gz' saved [14131146/14131146]

Download done.
Flash Plugin installed.



# apt-get install flashplugin-installer=11.2.202.235ubuntu0.12.04.1
Reading package lists... Done
Building dependency tree
Reading state information... Done
Suggested packages:
  ttf-xfree86-nonfree xfs
The following packages will be upgraded:
  flashplugin-installer
1 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
Need to get 0 B/8346 B of archives.
After this operation, 32.8 kB of additional disk space will be used.
Preconfiguring packages ...
(Reading database ... 683919 files and directories currently installed.)
Preparing to replace flashplugin-installer 11.2.202.235ubuntu0.11.10.1 (using .../flashplugin-installer_11.2.202.235ubuntu0.12.04.1_i386.deb) ...
Unpacking replacement flashplugin-installer ...
Processing triggers for update-notifier-common ...
flashplugin-installer: downloading http://archive.canonical.com/pool/partner/a/adobe-flashplugin/adobe-flashplugin_11.2.202.235.orig.tar.gz
Traceback (most recent call last):
  File "/usr/lib/update-notifier/package-data-downloader", line 234, in process_download_requests
    dest_file = urllib.urlretrieve(files[i])[0]
  File "/usr/lib/python2.7/urllib.py", line 93, in urlretrieve
    return _urlopener.retrieve(url, filename, reporthook, data)
  File "/usr/lib/python2.7/urllib.py", line 239, in retrieve
    fp = self.open(url, data)
  File "/usr/lib/python2.7/urllib.py", line 207, in open
    return getattr(self, name)(url)
  File "/usr/lib/python2.7/urllib.py", line 344, in open_http
    h.endheaders(data)
  File "/usr/lib/python2.7/httplib.py", line 954, in endheaders
    self._send_output(message_body)
  File "/usr/lib/python2.7/httplib.py", line 814, in _send_output
    self.send(msg)
  File "/usr/lib/python2.7/httplib.py", line 776, in send
    self.connect()
  File "/usr/lib/python2.7/httplib.py", line 757, in connect
    self.timeout, self.source_address)
  File "/usr/lib/python2.7/socket.py", line 553, in create_connection
    for res in getaddrinfo(host, port, 0, SOCK_STREAM):
IOError: [Errno socket error] [Errno -2] Name or service not known
Setting up flashplugin-installer (11.2.202.235ubuntu0.12.04.1) ...