Re: [SSHGuard-users] Call for testing: SSHGuard 1.7.0

[Georg L. <jor...@ma...>]

On 28/07/16 19:08, Kevin Zheng wrote:
> On 07/28/2016 10:27, Georg Lehner wrote:
>> - The sshg-fw script stops with syntax error, a patch with some
>>   improvements (hopefully) is attached.
>
> Thanks for the patch. Just to make sure, what does 'iptables -w -v' do?
> I can't seem to tell from the man page [1] what the default action is.
>
> [1] http://linuxmanpages.net/manpages/fedora21/man8/iptables.8.html
>
Hello Kevin,

It should be `-V` (--version), instead of `-v`.

I'm sure you remember, that I have a system with an old `iptables` which 
does not understand the `-w` switch.

Since I have a system with a new `iptables`too, I was able to find a 
way, to detect non-intrusively if `-w` is supported.

`iptables -w -V` will exit with an error and a message on stderr if it 
is an old `iptables`.  If it is a new `iptables` it will show its 
version on stdout and exit with success.

I proposed: `if $cmd -w -v 2>/dev/null; then ...` in my patch, however 
it better be:

`if $cmd -w -V 2>&1 >/dev/null; then ...`

to suppress the version string too.

Best Regards,

   Georg Lehner