According to at least one report, there are some slightly insane servers out
there that have /dev/null set to non-user-writable. This is totally broken,
but we want sshuttle to work with as many servers as possible, so let's fake
it up a bit instead.
We don't try to avoid /dev/null on the client; sshuttle needs root access
anyway, and if you're root, you can just fix your stupid /dev/null
permissions.
If the ~/.sshuttle.hosts file does not exist, it triggers the following
error:
Traceback (most recent call last):
File "./sshuttle", line 80, in <module>
sys.exit(hostwatch.hw_main(extra))
File "/home/def/p/sshuttle/hostwatch.py", line 246, in hw_main
read_host_cache()
File "/home/def/p/sshuttle/hostwatch.py", line 41, in read_host_cache
if e.errno == errno.ENOENT:
NameError: global name 'errno' is not defined
(This only happened if you run 'sshuttle --hostwatch' from the command line
directly, without passing it through assembler.py.)
Now if you use --auto-hosts (-H), the client will ask the server to spawn a
hostwatcher to add names. That, in turn, will send names back to the
server, which sends them back to the client, which sends them to the
firewall subprocess, which will write them to /etc/hosts. Whew!
Only the firewall process can write to /etc/hosts, of course, because only
he's running as root.
Since the name discovery process is kind of slow, we cache the names in
~/.sshuttle.hosts on the remote server.
Right now, most of the names are discovered using nmblookup and smbclient,
as well as by reading the existing entries in /etc/hosts. What would really
be nice would be to query active directory or mdns somehow... but I don't
really know how those work, so this is what you get for now :) It's pretty
neat, at least.
