Category: linux

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Bash random number generation

Historically I’ve used $RANDOM as a random number source in bash — a bit like :

RAND=$(( $RANDOM % 10 ))

when I’ve needed a random number out of 0,1,2,3,4,5,6,7,8 and 9

one problem with this is that $RANDOM itself is populated between 0 and 32767 by the shell – so it’s not going to give totally even distribution.

Finally, I discovered ‘shuf’ — usage like :

shuf -i 1-100 -n 1

-i RangeFrom-RangeTo
-n how many

So –

RAND=$(( shuf -i 1-10 -n 1))
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Squid 3.4.x for with transparent ssl proxying/support for Debian Wheezy.

I needed  a variant of Squid which supported transparent SSL interception (i.e via iptables redirection) so I could log outgoing HTTPS requests without the client being aware.

The stock wheezy variant doesn’t support SSL (see : Debian Bug Report).

Even after recompiling Wheezy’s squid3 it didn’t seem to work (perhaps my stupidity) so I ended up moving to the latest-and-greatest squid (3.4.9 at the time of writing) and getting that to work. Brief notes follow.

Continue reading “Squid 3.4.x for with transparent ssl proxying/support for Debian Wheezy.”

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Debian http_proxy setting

Need to set a HTTP proxy within a Debian system ?

Assuming your proxy server is on 192.168.0.1 and listening on port 3128, then the below may help …

( If you need authentication you can use username:password@ like you would in an old style web browser – e.g. http://username:password@192.168.0.1:3128. )

/etc/profile.d/proxy.sh

Add /etc/profile.d/proxy.sh containing

export http_proxy=http://192.168.0.1:3128

/etc/apt/apt.conf.d/99HttpProxy

Add /etc/apt/apt.conf.d/99HttpProxy containing

Acquire::http::Proxy "http://192.168.0.1:3128";

/etc/wgetrc

Edit /etc/wgetrc and add

http_proxy = http://192.168.0.1:3128

(some system commands rely on wget, and may not otherwise use an environment variable, e.g. debootstrap; the http_proxy setting should be present by default but commented out).

(This is all, in a round about way, relayed to the http proxy security vulnerability announced in July 2016 – see httpoxy.org for more info)