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]

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