Archive for Ulisses Féres

ATA linksys, cisco e sipura perdem registro sip (asterisk) quando atrás de nat masquerad MIKROTIK

Esse problema é muito comum e muitas das vezes pode ser observado quando o ATA perde o registro sip ao asterisk e, retorna momentaneamente e instantaneamente somente se:

1 – Trocar a porta UDP de X para outra Y. (Exemplo: de 5061 para 5064)
2 – Limpar os registros sip do Mikrotik com script:


     /ip firewall connection remove [/ip firewall connection find where connection-type=sip and assured=no]
     /ip firewall connection remove [find where dst-address~"IP DO DESTINO, ASTERISK"]
     /ip firewall connection remove [find where connection-type=sip or connection-type=sip-2 or connection-type=sip-1]

Porem se o script 2 for executado as chamadas correntes são derrubadas.

Uma solução que encontrei é trocar o NAT Masquerad por NAT src-nat, onde eu pego o IP Real fixo ou mesmo o IP da VPN sainte e coloco no TO ADDRESS (item irá aparecer quando trocar o MASQUERADE por SRC-NAT)

Se seu ip na WAN for dinâmico (eu possuo pppoe dinamico) pode-se criar um script de exemplo:

:global newIP [/ip address get [find interface="fibra-pppoe"] address] 
/ip firewall nat set [find where comment="PPPoE NAT"] to-address=$newIP

Onde o fibra-pppoe é o nome da interface pppoe, e o PPPoE NAT é um comentário que tenho obrigatoriamente deixar na regra de SRC-NAT do firewall

E lembre-se de criar um agendamento para rodar esse script de 5 em 5 minutos.

Tabela no mysql crashed “is marked as crashed and last (automatic?) repair failed”


#144 - Table './mya2billing/cc_call' is marked as crashed and last (automatic?) repair failed
ERROR 144 - Table 'BLABLABLABLABL' is marked as crashed and last (automatic?) repair failed

If your MySQL process is running, stop it. On Debian/Red Hat/Centos:

sudo service mysql stop
/etc/init.d/mysql stop

Go to your data folder. On Debian:

cd /var/lib/mysql/$DATABASE_NAME

Try running:

myisamchk -r $TABLE_NAME

If that doesn’t work, you can try:

myisamchk -r -v -f $TABLE_NAME

You can start your MySQL server again. On Debian:

sudo service mysql start
or /etc/init.d/mysql start

Brother printers: how to install them in Linux Mint


A Brother printer is nowadays easily installable in Linux Mint. You can apply this how-to:

1. Connect your printer to your computer by means of a USB cable (even when you intend to use it as a network printer later on: for initial installation a USB cable is often needed). Then turn on your printer.

2. Sometimes it’s necessary to add a printer or scanner to the system yourself, by means of the application Printers. In that case the application Printers already contains the driver for your printer, but you have to “indicate” the printer first.

So launch the application Printers. You can use the search box in your menu to find it; it’s present by default in all editions of Linux Mint.

In Printers, click the button Add (with the + sign) and follow the steps it offers you.

But in some cases this driver doesn’t work well: the printed characters are deformed. Or if you have a multifunctional printer, this doesn’t get the scanner part operational: you can only print. Or your printer might simply be too new for the database in your version of Linux Mint. In either of those cases, proceed with step 3:

3. Installing the driver manually isn’t very difficult either, because Brother has issued a generic install script for that: the Driver Install Tool.

With that, you can install not only the printer driver, but also (for a multifunctional printer) the scanner driver.

You can use it as follows:

4. First remove any existing instance of the Brother printer in the application Printers.

5. Go to the download section of the Brother website and look up your printer model.

For “OS Family” you choose Linux.
For “OS Version” you select Linux (deb).
Click the Search button.

Then click the Driver Install Tool and download linux-brprinter-installer.

Save the downloaded file in the folder Downloads. Don’t extract the zipped file, but leave it there just as it is. Note: don’t use the installation how-to on the Brother website, but use the installation how-to on my website instead (see below)!

6. Launch a terminal linux.

d. Now copy/paste the following command into the terminal, in order to unzip the downloaded file (it’s one line):

cd ~/Downloads && gunzip -v ~/Downloads/linux-brprinter*

Press Enter.

7. Use copy/paste to transfer the following line to the terminal:

sudo bash ~/Downloads/linux-brprinter*

Press Enter. Type your password when prompted; this will remain entirely invisible, not even asterisks will show, which is normal.

8. Follow the steps that the installer script presents you. When asked for the printer model name, type it and press Enter.

An example is best: for a Brother DCP-1610W you type:


Note: is there at the end of the model name a letter between brackets? Then you probably have to omit that last letter (including the brackets).

Example: for the Brother MFC-L9550CDW(T) it becomes:


At the question about the Device URI, you answer N for a USB printer and Y for a network printer.

For a network printer, you select in the next question the last option:
(A): Auto. For that, you type the number of that option and you press Enter.

9. Reboot your computer.

10. Now you may have to solve a problem with the scanner. In 64-bit Linux Mint 19 the location for the supporting library files has changed, and the driver for the scanner feature doesn’t always take that into account. The Brother driver then puts them in /usr/lib64, whereas your operating system expects them in /usr/lib.

So for a 64-bit system, you now need to execute the following three commands in order to make your scanner work well (use copy/paste to transfer them one by one to the terminal, and press Enter after each command):

sudo ln -sf /usr/lib64/libbrscandec*.so* /usr/lib

sudo mkdir -p /usr/lib/sane

sudo ln -sf /usr/lib64/sane/libsane-brother*.so* /usr/lib/sane

11. Then add yourself to the scanner user group. You can use a click-click-click graphical system tool for that, but this varies amongst editions. The terminal works in all editions….

An example is easiest. If your name is Johnny, your username is johnny (no caps), so the terminal command would be:

sudo usermod -a -G scanner johnny

Press Enter.

12.Now open a settings file with Xed, using the following command (use copy/paste to transfer it to the terminal):

xed admin:///lib/udev/rules.d/60-libsane1.rules

(The three consecutive dashes are intentional)

Press Enter.

13. At the very end of the text in that long text file, you see this line:

# LABEL="libsane_rules_end".

Now add the following two lines right above that line: (use copy/paste to transfer them):

# Brother scanners

ATTRS{idVendor}=="04f9", ENV{libsane_matched}="yes"

14. Reboot your computer.

15. Printers with wifi: for wireless setup, it’s necessary to configure your printer to connect to your wireless network automatically. If your printer has a small display of its own, you should be able to set this up by means of that little display (see your manual).

If your printer doesn’t have a display of its own, you might need to boot Windows for this. One time only, because you only need to configure the printer to connect to your wireless network automatically when you turn it on. Reboot into Linux, launch the application Printers, and you should be able to select your network printer wirelessly.

16. You’re done! Your printer should work fine now, including the scanner part (when present).

Regras firewall para openvpn

Regras para passar trafego pelo iptables:


tun0 – interface openvpn
eth0 – lan

# vpn
iptables -A INPUT -i tun0 -j ACCEPT

# openvpn
iptables -t nat -A POSTROUTING -s -o eth0 -j MASQUERADE

iptables -A FORWARD -i tun0 -j ACCEPT
iptables -A FORWARD -i tun0 -o eth0 -m state –state RELATED,ESTABLISHED -j ACCEPT
iptables -A FORWARD -i eth0 -o tun0 -m state –state RELATED,ESTABLISHED -j ACCEPT

# aceitar a openvpn
iptables -A INPUT -p udp –dport 1195 -j ACCEPT

RSSI para dBm


A maioria dos fabricantes de radios usa dBm – potencia em decibéis – (abbreviation for the power ratio in decibels (dB)) como medida de potencia de sinal.

Alguns poucos usam RSSI -potencia em porcentagem (received signal strength indication (RSSI)) como forma de medir a potencia do sinal.

Neste site você encontra a forma de calcular e comparar as duas formas de medir a potencia dos rádios

Veja a tabela comparativa RSSI x dBm

Conversion for Cisco

Cisco has the most granular dBm lookup table.

RSSI_Max = 100

Convert % to RSSI and lookup the result in the following table. The RSSI is on the left,

and the corresponding dBm value (a negative number) is on the right.

0 = -113

1 = -112

2 = -111

3 = -110

4 = -109

5 = -108

6 = -107

7 = -106

8 = -105

9 = -104

10 = -103

11 = -102

12 = -101

13 = -99

14 = -98

15 = -97

16 = -96

17 = -95

18 = -94

19 = -93

20 = -92

21 = -91

22 = -90

23 = -89

24 = -88

25 = -87

26 = -86

27 = -85

28 = -84

29 = -83

30 = -82

31 = -81

32 = -80

33 = -79

34 = -78

35 = -77

36 = -75

37 = -74

38 = -73

39 = -72

40 = -70

41 = -69

42 = -68

43 = -67

44 = -65

45 = -64

46 = -63

47 = -62

48 = -60

49 = -59

50 = -58

51 = -56

52 = -55

53 = -53

54 = -52

55 = -50

56 = -50

57 = -49

58 = -48

59 = -48

60 = -47

61 = -46

62 = -45

63 = -44

64 = -44

65 = -43

66 = -42

67 = -42

68 = -41

69 = -40

70 = -39

71 = -38

72 = -37

73 = -35

74 = -34

75 = -33

76 = -32

77 = -30

78 = -29

79 = -28

80 = -27

81 = -25

82 = -24

83 = -23

84 = -22

85 = -20

86 = -19

87 = -18

88 = -17

89 = -16

90 = -15

91 = -14

92 = -13

93 = -12

94 = -10

95 = -10

96 = -10

97 = -10

98 = -10

99 = -10

100 = -10

Notice that this gives a range of –10dBm to –113dBm. Bearing in mind that a Cisco card

will have a Receive Sensitivity of –96dBm at its lowest, it is impossible to obtain an RSSI

value of less than 16. Note, also, that all RSSI values greater than 93 are assigned

–10dBm, and that there are multiple places in the table where two adjacent RSSI values

are assigned the same dBm value.