or when you have no root access...
On Tue, May 25, 2021 at 11:14 AM Walter Harms wrote:
>
> yes, under normal circumstances you would use iptables to block the port. But
> when you are forced to byte-counting and you do not want to install other
> programms (and maintains them) on your embedded system, this is clearly an
> option.
>
> re,
> wh
>
> Von: Steffen Nurpmeso
> Gesendet: Dienstag, 25. Mai 2021 02:40:50
> An: Walter Harms
> Cc: dropbear@ucc.asn.au
> Betreff: Re: restrict access
>
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>
> Walter Harms wrote in
> :
> |I did a little experiment and it worked.
> |
> | if (fnmatch("192.168.1.*",remote_host,FNM_PATHNAME) != 0)
> | goto out;
> |
> |this will allow only connections from 192.168.1.* to the server
> |that shows the change can be very simple. I did not try with more compli\
> |cated situations. The limits of this approach needs to be evaluated.
>
> Since the begin of this thread this sounds like a 100% firewall
> thing to me. Why would you like to compile this in?
>
> I mean, i can imagine the NetBSD/FreeBSD black(now block)list
> approach in which a server software who "knows" what has happened
> acts via a hook instead of let some expensive log parser
> reevaluate state which is known in the moment the log happens.
>
> But this? I am not an administrator and thus firewall guru, but
> i for example have in my net-qos.sh:fwcore_start() (heavily
> vaporised this is)
>
>change_chain INPUT
>new_chain i_good i_alien i_sshorvpn i_tcp_new
>
>add_rule -m conntrack --ctstate RELATED,ESTABLISHED -j ACCEPT
>
>add_rule -j i_good
>add_rule -j i_alien
>
>add_rule -p tcp --syn -m conntrack --ctstate NEW -j i_tcp_new
>
>change_chain i_tcp_new
>
>fwcore_has_i ssh && add_rule -p tcp --dport ${p_ssh} -j i_sshorvpn
>
>change_chain i_sshorvpn
>
> So and in here you can allow or deny ssh-specific anyway you want
> to, add, remove and change, use "-m recent" and hitcounts etc.,
> and all without recompilation. (Having real address and/or CIDR
> tables which could be managed separately would be cool though.)
>
> --steffen
> |
> |Der Kragenbaer,The moon bear,
> |der holt sich munter he cheerfully and one by one
> |einen nach dem anderen runter wa.ks himself off
> |(By Robert Gernhardt)
