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Some ports generate an error (ERR_UNSAFE_PORT) when browsing to them via Chrome (see this related question). Which ports are considered safe, and which are unsafe by default?

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  • 3
    Note: Google have recently added port 10080 to this list.
    – mwfearnley
    Jun 11, 2021 at 10:00

3 Answers 3

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The following is a list of all of the restricted ports on Chrome:

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
69,     // tftp
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
137,    // netbios
139,    // netbios
143,    // imap2
161,    // snmp
179,    // BGP
389,    // ldap
427,    // SLP (Also used by Apple Filing Protocol)
465,    // smtp+ssl
512,    // print / exec
513,    // login
514,    // shell
515,    // printer
526,    // tempo
530,    // courier
531,    // chat
532,    // netnews
540,    // uucp
548,    // AFP (Apple Filing Protocol)
554,    // rtsp
556,    // remotefs
563,    // nntp+ssl
587,    // smtp (rfc6409)
601,    // syslog-conn (rfc3195)
636,    // ldap+ssl
993,    // ldap+ssl
995,    // pop3+ssl
1719,   // h323gatestat
1720,   // h323hostcall
1723,   // pptp
2049,   // nfs
3659,   // apple-sasl / PasswordServer
4045,   // lockd
5060,   // sip
5061,   // sips
6000,   // X11
6566,   // sane-port
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]
6697,   // IRC + TLS
10080,  // Amanda

Source: Chrome source.

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    And the Mozilla Firefox Unsafe Portslist for good measure: www-archive.mozilla.org/projects/netlib/…
    – coolaj86
    Jun 28, 2012 at 21:37
  • Thanks, this was very helpful in figuring out why my ZNC server didn't appear to be working properly
    – Hamy
    Jun 29, 2014 at 5:23
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    as of 2017, 65535 is also considered "unsafe". I have no idea why err_unsafe_ports applies to requests to localhost (clearly requests to localhost should mean I am a developer or I am otherwise purposefully proxying requests via localhost).
    – cowbert
    Feb 13, 2018 at 0:00
  • @cowbert your assumption is invalid. It could be an XSS or malicious website making requests to localhost.
    – cytinus
    Jan 30, 2019 at 17:36
  • 6697 is also a restricted port. There are definitely additional ones not listed in this segment of the source code. Someone who knows more about this should add to this answer.
    – AndrewF
    Mar 18, 2019 at 23:49
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The reason it's called unsafe is not because it's unsafe to Chrome, it's because it's unsafe to those services, where an attacker may try to use Chrome as a proxy to attacking services on those ports. More explanation here:

http://jazzy.id.au/default/2012/08/23/why_does_chrome_consider_some_ports_unsafe.html

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by default web services normally run on port 80 and SSL encrypted traffic runs on port 443 so these should be "safe" ports. This is typically known as "default ports" or "well known ports". "safe" seems to be a chrome-ism :)

"safe" is a bit meaningless though. If it runs on anouther port its more likely to be dodgy traffic, but just because its on port 80 dosent mean it wont install malware and etc on your pc.

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    There's no reason why traffic on non-default ports would be dodgy. For example non-default ports are used on unix machines where the web server is administered completely independently from the local administrator (unix restricts servers on ports <1024 to the system administrator). Such setups are very rare nowadays because the economic conditions of web hosting have changed, but there's nothing illegitimate about them.
    – Gilles 'SO- stop being evil'
    Sep 13, 2010 at 18:16
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    the above is true, but im not going to be clicking any urls that specify a port number.
    – Sirex
    Sep 13, 2010 at 22:06
  • @Sirex By the way, is it about the port number or the connection scheme being used? For example if a URL is like: https://<domain_name>:20/<path_name> there is no reason to worry right? Because it specifies a secure connection scheme. Although it is on the FTP port (an unsafe considered port), if the port doesn't run https, then there won't be any connection after all right? So is it about the port number or the connection scheme? (By the way, I am not trying to be a smart-ass. I am trying to understand what is safe and what is not and why)
    – Utku
    Nov 5, 2015 at 14:39
  • Usually, though its possible for a ssl encrypted site to install malware on your pc, the https just means it'll do so securely. It's not a designation of the traffic being safe. It's a designation of the traffic being secure. It could also be an invalid ssl certificate, but that'll give warnings in your browser. The short answer is nothing is truly safe, unless you know the sender of the information, and know the channel is private.
    – Sirex
    Nov 5, 2015 at 19:05
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    In the age of webservices this is absolutely false. Even in 2010, the default ports for web application servers like Tomcat or Unicorn was 8080 or 8443. Unix restricts ports < 1024 to running as root and nobody in 2010 would be running web application servers (apache http is special since it knows how to su to a non-privileged user after starting master process as root) on port 80 or 443.
    – cowbert
    Feb 13, 2018 at 0:05

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