Repairing a dead slow laptop

This is how I dealt with “repairing a dead slow laptop” according to the customer/owner.

Some details about the laptop:

Processor: Intel i5
RAM: 8 GB
Operating System: Windows 10 Home

Overall, a gorgeous laptop but running dead slow!

The reason for a dead slow laptop, in this case, was an erratic hard disk (C drive): Errors in the main hard drive, probably due to fall!

My initial “logging in” into the computer took a whole night (as Administrator) because, you guessed it, the laptop was running very slow!

So, I entered user name and password with administrative privileges before going to sleep and i was logged at least after four hours!

So, after fixing the hard disk errors by running chkdsk \f (with Administrator privileges), the dead slow laptop resumed its normal speed which was pretty good.

Customer happy; I am happy!

CentOS 7 docker container with Perl/Mojolicious

Requirements:

  1.  A running/live docker installation
  2. An open/available port on the host to access the newly installed container (4003 in this example)
  3. A basic understanding of docker containerization technology.

I ran into a network problem. A simple restart of docker service fixed it.

[root@ns24 ~]#docker run -d –publish 4003:80 a2zdotblue/c7-systemd-perl-mojo-02

Digest: sha256:a6a808fd286b1af1aa5ee46d5fa2eac2b61b02ecff234101bd098596a3b2a1f4
Status: Downloaded newer image for docker.io/a2zdotblue/c7-systemd-perl-mojo-02:latest
f07bfaab03efc10ceed140c04238746a4ba5edb54c01bb22b7af95648a38260c
/usr/bin/docker-current: Error response from daemon: driver failed programming external connectivity on endpoint lucid_swirles (d240ed06c8cb4f3a366e53acf1554ec6b437e296659f53646e8ad08f1e0c7129): (iptables failed: iptables –wait -t nat -A DOCKER -p tcp -d 0/0 –dport 4003 -j DNAT –to-destination 172.17.0.2:80 ! -i docker0: iptables: No chain/target/match by that name.
(exit status 1)).

[root@ns24 ~]# service docker restart


Redirecting to /bin/systemctl restart docker.service

Rerun code after docker restart

[root@ns24 ~] # docker run -d –publish 4003:80 a2zdotblue/c7-systemd-perl-mojo-02


cc422a9d647e71478ace6bb9a7e48b5034f66cc2142c830ebc0381469a92a34f

Log into the Container:

[root@ns24 ~]# docker exec -it cc422a9d647e /bin/bash

[root@cc422a9d647e app]

The Mojolicious sample app uses port 80 inside the container. Run hypnotoad (yes, already installed inside the container along with Mojoloicious Web Framework)

In docker terminology, port 80 is exposed for this app.

[root@cc422a9d647e app]# hypnotoad perlmojo/script/perlmojo


[Thu Aug 16 15:01:46 2018] [info] Listening at “http://*:80”
Server available at http://127.0.0.1:80

The above output confirms that the app is working and you can always update the app by logging into the live container!

Actually this example is live at ns24.a1z.us. It is accessible as long as my ISP provides/maintains good connection or until I decide to take it down!

Firefox and Chrome – blocked/unsafe ports

I used a port, 6666, which happened to be blocked by both Firefox and Chrome browsers. So after a little research, I understood that some ports are blocked by default including the one I used by both browsers. Hence this post on all blocked ports by them.

Mozilla Firefox

https://www-archive.mozilla.org/projects/netlib/PortBanning.html#portlist
Mozilla Firefox blocked/unsafe ports
1tcpmux
7echo
9discard
11systat
13daytime
15netstat
17qotd
19chargen
20ftp data
21ftp control
22ssh
23telnet
25smtp
37time
42name
43nicname
53domain
77priv-rjs
79finger
87ttylink
95supdup
101hostriame
102iso-tsap
103gppitnp
104acr-nema
109POP2
110POP3
111sunrpc
113auth
115sftp
117uucp-path
119NNTP
123NTP
135loc-srv / epmap
139netbios
143IMAP2
179BGP
389LDAP
465SMTP+SSL
512print / exec
513login
514shell
515printer
526tempo
530courier
531chat
532netnews
540uucp
556remotefs
563NNTP+SSL
587submission
601syslog
636LDAP+SSL
993IMAP+SSL
995POP3+SSL
2049nfs
4045lockd
6000X11

Google Chrome

https://src.chromium.org/viewvc/chrome/trunk/src/net/base/net_util.cc?view=markup
Google Chrome blocked/unsafe ports
  1,    // tcpmux
  7,    // echo
  9,    // discard
  11,   // systat
  13,   // daytime
  15,   // netstat
  17,   // qotd
  19,   // chargen
  20,   // ftp data
  21,   // ftp access
  22,   // ssh
  23,   // telnet
  25,   // smtp
  37,   // time
  42,   // name
  43,   // nicname
  53,   // domain
  77,   // priv-rjs
  79,   // finger
  87,   // ttylink
  95,   // supdup
  101,  // hostriame
  102,  // iso-tsap
  103,  // gppitnp
  104,  // acr-nema
  109,  // pop2
  110,  // pop3
  111,  // sunrpc
  113,  // auth
  115,  // sftp
  117,  // uucp-path
  119,  // nntp
  123,  // NTP
  135,  // loc-srv /epmap
  139,  // netbios
  143,  // imap2
  179,  // BGP
  389,  // ldap
  465,  // smtp+ssl
  512,  // print / exec
  513,  // login
  514,  // shell
  515,  // printer
  526,  // tempo
  530,  // courier
  531,  // chat
  532,  // netnews
  540,  // uucp
  556,  // remotefs
  563,  // nntp+ssl
  587,  // stmp?
  601,  // ??
  636,  // ldap+ssl
  993,  // ldap+ssl
  995,  // pop3+ssl
  2049, // nfs
  3659, // apple-sasl / PasswordServer
  4045, // lockd
  6000, // X11
  6665, // Alternate IRC [Apple addition]
  6666, // Alternate IRC [Apple addition]
  6667, // Standard IRC [Apple addition]
  6668, // Alternate IRC [Apple addition]
  6669, // Alternate IRC [Apple addition]