pnc

Using OTP's observer (appmon replacement) remotely

$ ssh remote-host "epmd -names"
epmd: up and running on port 4369 with data:
name some_node at port 58769

Note the running on port for epmd itself and the port of the node you're interested in debugging. Reconnect to the remote host with these ports forwarded:

$ ssh -L 4369:localhost:4369 -L 58769:localhost:58769 remote-host

scy

My OS X “VPN only” Setup For #30C3

You should never let passwords or private data be transmitted over an untrusted network (your neighbor’s, the one at Starbucks or the company) anyway, but on a hacker congress like the #30C3, this rule is almost vital.

Hackers get bored easily, and when they’re bored, they’re starting to look for things to play with. And a network with several thousand connected users is certainly an interesting thing to play with. Some of them might start intercepting the data on the network or do other nasty things with the packets that they can get.

If these packets are encrypted, messing with them is much harder (but not impossible! – see the end of this article). So you want your packets to be always encrypted. And the best way to do that is by using a VPN.

Target audience

angrycub

##Using Force Replace to Change a nodes IP address. ###Objective Previous to Riak 1.2, a cluster node's IP address could be changed by running riak-admin reip on each cluster node. As of Riak 1.2, this method has been replaced with riak-admin cluster force-replace which is safer and does not require any downtime.

###Scenario

Riak is running in a cluster of five nodes.

• riak@64.214.83.25 on node1.localdomain (192.168.17.11)(64.214.83.25)
• riak@64.214.83.26 on node2.localdomain (192.168.17.12)(64.214.83.26)

w495

%%
%% @file    test_concat.erl тестирование скорости конкатенации
%%          Тестирование проводилось на списках и binary.
%%          Тестировалось наивная конкатенация через:
%%              * ++, для списков;
%%              * <<X/binary,Y/binary>>>, для binary;
%%              * вложенные списки (правильные и неправильные), cм ниже;
%%              * конкатенация через lists:append, для списков;
%%              * конкатенация через string:join, для списков;
%%

gdamjan

%%% This macro will create a function that converts a record to
%%% a {key, value} list (a proplist)

-define(record_to_list(Record),
    fun(Val) ->
        Fields = record_info(fields, Record),
        [_Tag| Values] = tuple_to_list(Val),
        lists:zip(Fields, Values)
    end
).

gdamjan

%%%   This is a clever Erlang macro that given a record name will create a new function
%%%   that converts from a property list to the record (which really is a taged tuple).

-define(proplist_to_record(Record),
   fun(Proplist) ->
       Fields = record_info(fields, Record),
       [Tag| Values] = tuple_to_list(#Record{}),
       Defaults = lists:zip(Fields, Values),
       L = lists:map(fun ({K,V}) -> proplists:get_value(K, Proplist, V) end, Defaults),
       list_to_tuple([Tag|L])