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Posted to users@tomcat.apache.org by Amit Pande <Am...@veritas.com.INVALID> on 2023/08/06 17:25:34 UTC
RE: [External] Re: listening all local addresses by default is not security best practice
My apologies if I missed any conclusion here.
From the description of address attribute on HTTP connector:
"For servers with more than one IP address, this attribute specifies which address will be used for listening on the specified port. By default, the connector will listen all local addresses. Unless the JVM is configured otherwise using system properties, the Java based connectors (NIO, NIO2) will listen on both IPv4 and IPv6 addresses when configured with either 0.0.0.0 or ::. The APR/native connector will only listen on IPv4 addresses if configured with 0.0.0.0 and will listen on IPv6 addresses (and optionally IPv4 addresses depending on the setting of ipv6v6only) if configured with ::."
Is it possible to update the behavior to listen to loopback address only like was done for AJP connectors.
On my Tomcat 9.0.78 netstat output - I see Tomcat using 0.0.0.0 by default unless we define address as "127.0.0.1" :
tcp 0 0 0.0.0.0:39054 0.0.0.0:* LISTEN 28539/java
Also, is it right that we will need to have two connectors for IPv4 and IPv6 with address "127.0.0.1" and "::1" respectively to enable binding only on loopback addresses?
If we configure two connectors (IPv4 and IPv6 loopback), if one isn't available, we see:
org.apache.catalina.LifecycleException: Protocol handler initialization failed
at org.apache.catalina.connector.Connector.initInternal(Connector.java:1011)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
at org.apache.catalina.core.StandardService.initInternal(StandardService.java:549)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
at org.apache.catalina.core.StandardServer.initInternal(StandardServer.java:1040)
at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
at org.apache.catalina.startup.Catalina.load(Catalina.java:724)
at org.apache.catalina.startup.Catalina.load(Catalina.java:746)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:307)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:477)
Caused by: java.net.SocketException: Protocol family unavailable
at sun.nio.ch.Net.bind0(Native Method)
which has caused confusion/concerns.
What would be a better way to bind on "all available loopback addresses?
Thanks,
Amit
-----Original Message-----
From: Christopher Schultz <ch...@christopherschultz.net>
Sent: Monday, November 28, 2022 5:21 PM
To: users@tomcat.apache.org
Subject: [External] Re: listening all local addresses by default is not security best practice
To whom it may concern,
On 11/23/22 14:31, tommydu1123@outlook.com wrote:
> Hi there,
>
> Product:<https://nam12.safelinks.protection.outlook.com/?url=https%3A%
> 2F%2Fbz.apache.org%2Fbugzilla%2Fdescribecomponents.cgi&data=05%7C0
> 1%7CAmit.Pande%40veritas.com%7C13ea9fddeb604e4b7dca08dad1978243%7Cfc8e
> 13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638052745907718347%7CUnknown%7C
> TWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVC
> I6Mn0%3D%7C3000%7C%7C%7C&sdata=o%2FwWU7LgTdFLS3L5njjEruLLho9JnSw2O
> LV0%2BO%2BnR5c%3D&reserved=0>
>
> [snip]
> The default behaviour of http connector is listenning all interfaces.
False.
> It is found in the description of "address" in attributes section.
> (https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftom
> cat.apache.org%2Ftomcat-9.0-doc%2Fconfig%2Fhttp.html%23SSL_Support&
> ;data=05%7C01%7CAmit.Pande%40veritas.com%7C13ea9fddeb604e4b7dca08dad19
> 78243%7Cfc8e13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638052745907718347%
> 7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik
> 1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=p3R8MryiKpauAppYJLbrGLP
> FzIUJpONDxvQj%2BlYepnI%3D&reserved=0)
It's listed in another section, and does not say all interfaces.
> In terms of security default, it could be not best practice. In case of unexpected mistakes made by people, default behaviour of exposing the server to every possible network may pose a potential threat on security.
Good thing Tomcat does not default to that configuration.
> CWE-1327: Binding to an Unrestricted IP Address:
> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcwe.
> mitre.org%2Fdata%2Fdefinitions%2F1327.html&data=05%7C01%7CAmit.Pan
> de%40veritas.com%7C13ea9fddeb604e4b7dca08dad1978243%7Cfc8e13c0422c4c55
> b3eaca318e6cac32%7C0%7C0%7C638052745907718347%7CUnknown%7CTWFpbGZsb3d8
> eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3
> 000%7C%7C%7C&sdata=pZzdfOpc0Cw5kVThNxWZLBZIoW4xXQSoSldTtMn6OEM%3D&
> amp;reserved=0
>
> The issue should be a security enhancement. I recommend changing default behaviour to a single interface/network, e.g loopback interface 127.0.0.1 and adding configuration option with default value OFF for 0.0.0.0 or : :.
Sounds great. So what exactly needs to be changed? You want us to pick only IPv4 or IPv6?
If not, what you describe is exactly the default configuration that you will get.
-chris
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RE: [External] Re: listening all local addresses by default is not security best practice
Posted by Amit Pande <Am...@veritas.com.INVALID>.
Thank you, Chris, for inputs.
I have created a BZ ticket: https://bz.apache.org/bugzilla/show_bug.cgi?id=67065
Thanks,
Amit
-----Original Message-----
From: Christopher Schultz <ch...@christopherschultz.net>
Sent: Monday, August 14, 2023 10:47 AM
To: Tomcat Users List <us...@tomcat.apache.org>
Subject: Re: [External] Re: listening all local addresses by default is not security best practice
CAUTION: This email originated from outside the organization. Do not click links or open attachments unless you recognize the sender and know the content is safe. If you believe this is a phishing email, use the Report to Cybersecurity icon in Outlook.
On 8/6/23 13:25, Amit Pande wrote:
> My apologies if I missed any conclusion here.
>
> From the description of address attribute on HTTP connector:
>
> "For servers with more than one IP address, this attribute specifies which address will be used for listening on the specified port. By default, the connector will listen all local addresses. Unless the JVM is configured otherwise using system properties, the Java based connectors (NIO, NIO2) will listen on both IPv4 and IPv6 addresses when configured with either 0.0.0.0 or ::. The APR/native connector will only listen on IPv4 addresses if configured with 0.0.0.0 and will listen on IPv6 addresses (and optionally IPv4 addresses depending on the setting of ipv6v6only) if configured with ::."
>
>
> Is it possible to update the behavior to listen to loopback address only like was done for AJP connectors.
>
> On my Tomcat 9.0.78 netstat output - I see Tomcat using 0.0.0.0 by default unless we define address as "127.0.0.1" :
>
> tcp 0 0 0.0.0.0:39054 0.0.0.0:* LISTEN 28539/java
Given the documentation quoted above, I would expect that Tomcat would bind to ::1 unless otherwise specified ("all LOCAL addresses", emphasis mine). The behavior you demonstrate above, and the code agree that Tomcat will listen on all PUBLIC interfaces, not local ones, by default.
I believe the documentation should be changed to reflect reality, because changing this default could break a lot of installations.
Changing the default AJP binding to localhost made sense because a publicly-exposed AJP connector is very insecure, while having HTTP(S) exposed publicly should not present much risk at all.
> Also, is it right that we will need to have two connectors for IPv4 and IPv6 with address "127.0.0.1" and "::1" respectively to enable binding only on loopback addresses?
>
> If we configure two connectors (IPv4 and IPv6 loopback), if one isn't available, we see:
>
>
> org.apache.catalina.LifecycleException: Protocol handler initialization failed
> at org.apache.catalina.connector.Connector.initInternal(Connector.java:1011)
> at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
> at org.apache.catalina.core.StandardService.initInternal(StandardService.java:549)
> at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
> at org.apache.catalina.core.StandardServer.initInternal(StandardServer.java:1040)
> at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
> at org.apache.catalina.startup.Catalina.load(Catalina.java:724)
> at org.apache.catalina.startup.Catalina.load(Catalina.java:746)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:498)
> at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:307)
> at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:477)
> Caused by: java.net.SocketException: Protocol family unavailable
> at sun.nio.ch.Net.bind0(Native Method)
>
> which has caused confusion/concerns.
>
> What would be a better way to bind on "all available loopback addresses?
That *would* be handy if ::1 would bind to "all local [IPv4 and IPv6, as appropriate] addresses" just like APR does. Can you please file a BZ ticket for that? I'm surprised it doesn't already work like that, honestly, because it seems completely obvious to me that's how it /should/ work.
-chris
> -----Original Message-----
> From: Christopher Schultz <ch...@christopherschultz.net>
> Sent: Monday, November 28, 2022 5:21 PM
> To: users@tomcat.apache.org
> Subject: [External] Re: listening all local addresses by default is
> not security best practice
>
> To whom it may concern,
>
> On 11/23/22 14:31, tommydu1123@outlook.com wrote:
>> Hi there,
>>
>> Product:<https://nam12.safelinks.protection.outlook.com/?url=https%3A
>> %
>> 2F%2Fbz.apache.org%2Fbugzilla%2Fdescribecomponents.cgi&data=05%7C
>> 0
>> 1%7CAmit.Pande%40veritas.com%7C13ea9fddeb604e4b7dca08dad1978243%7Cfc8
>> e
>> 13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638052745907718347%7CUnknown%7
>> C
>> TWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXV
>> C
>> I6Mn0%3D%7C3000%7C%7C%7C&sdata=o%2FwWU7LgTdFLS3L5njjEruLLho9JnSw2
>> O
>> LV0%2BO%2BnR5c%3D&reserved=0>
> >
> > [snip]
>> The default behaviour of http connector is listenning all interfaces.
>
> False.
>
>> It is found in the description of "address" in attributes section.
>> (https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fto
>> m%2F&data=05%7C01%7CAmit.Pande%40veritas.com%7C4e4302280bff44b9675908
>> db9cddbbbc%7Cfc8e13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C6382762483791
>> 42648%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJ
>> BTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=YG8QbOpd118rS4Nso7r
>> 1m%2BXiA2wa8ZqjfkrZIXD9x88%3D&reserved=0
>> cat.apache.org%2Ftomcat-9.0-doc%2Fconfig%2Fhttp.html%23SSL_Support&am
>> p
>> ;data=05%7C01%7CAmit.Pande%40veritas.com%7C13ea9fddeb604e4b7dca08dad1
>> 9
>> 78243%7Cfc8e13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638052745907718347
>> %
>> 7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6I
>> k
>> 1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=p3R8MryiKpauAppYJLbrGL
>> P
>> FzIUJpONDxvQj%2BlYepnI%3D&reserved=0)
> It's listed in another section, and does not say all interfaces.
>
>> In terms of security default, it could be not best practice. In case of unexpected mistakes made by people, default behaviour of exposing the server to every possible network may pose a potential threat on security.
>
> Good thing Tomcat does not default to that configuration.
>
>> CWE-1327: Binding to an Unrestricted IP Address:
>> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcwe%2F&data=05%7C01%7CAmit.Pande%40veritas.com%7C4e4302280bff44b9675908db9cddbbbc%7Cfc8e13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638276248379142648%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=7FogbHCUCEKXP5KXfM2y29IBS7rGtCUmSpgFbAqR5xY%3D&reserved=0.
>> mitre.org%2Fdata%2Fdefinitions%2F1327.html&data=05%7C01%7CAmit.Pa
>> n
>> de%40veritas.com%7C13ea9fddeb604e4b7dca08dad1978243%7Cfc8e13c0422c4c5
>> 5
>> b3eaca318e6cac32%7C0%7C0%7C638052745907718347%7CUnknown%7CTWFpbGZsb3d
>> 8
>> eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C
>> 3
>> 000%7C%7C%7C&sdata=pZzdfOpc0Cw5kVThNxWZLBZIoW4xXQSoSldTtMn6OEM%3D
>> &
>> amp;reserved=0
>>
>> The issue should be a security enhancement. I recommend changing default behaviour to a single interface/network, e.g loopback interface 127.0.0.1 and adding configuration option with default value OFF for 0.0.0.0 or : :.
>
> Sounds great. So what exactly needs to be changed? You want us to pick only IPv4 or IPv6?
>
> If not, what you describe is exactly the default configuration that you will get.
>
> -chris
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org
Re: [External] Re: listening all local addresses by default is not security best practice
Posted by Christopher Schultz <ch...@christopherschultz.net>.
On 8/6/23 13:25, Amit Pande wrote:
> My apologies if I missed any conclusion here.
>
> From the description of address attribute on HTTP connector:
>
> "For servers with more than one IP address, this attribute specifies which address will be used for listening on the specified port. By default, the connector will listen all local addresses. Unless the JVM is configured otherwise using system properties, the Java based connectors (NIO, NIO2) will listen on both IPv4 and IPv6 addresses when configured with either 0.0.0.0 or ::. The APR/native connector will only listen on IPv4 addresses if configured with 0.0.0.0 and will listen on IPv6 addresses (and optionally IPv4 addresses depending on the setting of ipv6v6only) if configured with ::."
>
>
> Is it possible to update the behavior to listen to loopback address only like was done for AJP connectors.
>
> On my Tomcat 9.0.78 netstat output - I see Tomcat using 0.0.0.0 by default unless we define address as "127.0.0.1" :
>
> tcp 0 0 0.0.0.0:39054 0.0.0.0:* LISTEN 28539/java
Given the documentation quoted above, I would expect that Tomcat would
bind to ::1 unless otherwise specified ("all LOCAL addresses", emphasis
mine). The behavior you demonstrate above, and the code agree that
Tomcat will listen on all PUBLIC interfaces, not local ones, by default.
I believe the documentation should be changed to reflect reality,
because changing this default could break a lot of installations.
Changing the default AJP binding to localhost made sense because a
publicly-exposed AJP connector is very insecure, while having HTTP(S)
exposed publicly should not present much risk at all.
> Also, is it right that we will need to have two connectors for IPv4 and IPv6 with address "127.0.0.1" and "::1" respectively to enable binding only on loopback addresses?
>
> If we configure two connectors (IPv4 and IPv6 loopback), if one isn't available, we see:
>
>
> org.apache.catalina.LifecycleException: Protocol handler initialization failed
> at org.apache.catalina.connector.Connector.initInternal(Connector.java:1011)
> at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
> at org.apache.catalina.core.StandardService.initInternal(StandardService.java:549)
> at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
> at org.apache.catalina.core.StandardServer.initInternal(StandardServer.java:1040)
> at org.apache.catalina.util.LifecycleBase.init(LifecycleBase.java:136)
> at org.apache.catalina.startup.Catalina.load(Catalina.java:724)
> at org.apache.catalina.startup.Catalina.load(Catalina.java:746)
> at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
> at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
> at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
> at java.lang.reflect.Method.invoke(Method.java:498)
> at org.apache.catalina.startup.Bootstrap.load(Bootstrap.java:307)
> at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:477)
> Caused by: java.net.SocketException: Protocol family unavailable
> at sun.nio.ch.Net.bind0(Native Method)
>
> which has caused confusion/concerns.
>
> What would be a better way to bind on "all available loopback addresses?
That *would* be handy if ::1 would bind to "all local [IPv4 and IPv6, as
appropriate] addresses" just like APR does. Can you please file a BZ
ticket for that? I'm surprised it doesn't already work like that,
honestly, because it seems completely obvious to me that's how it
/should/ work.
-chris
> -----Original Message-----
> From: Christopher Schultz <ch...@christopherschultz.net>
> Sent: Monday, November 28, 2022 5:21 PM
> To: users@tomcat.apache.org
> Subject: [External] Re: listening all local addresses by default is not security best practice
>
> To whom it may concern,
>
> On 11/23/22 14:31, tommydu1123@outlook.com wrote:
>> Hi there,
>>
>> Product:<https://nam12.safelinks.protection.outlook.com/?url=https%3A%
>> 2F%2Fbz.apache.org%2Fbugzilla%2Fdescribecomponents.cgi&data=05%7C0
>> 1%7CAmit.Pande%40veritas.com%7C13ea9fddeb604e4b7dca08dad1978243%7Cfc8e
>> 13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638052745907718347%7CUnknown%7C
>> TWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVC
>> I6Mn0%3D%7C3000%7C%7C%7C&sdata=o%2FwWU7LgTdFLS3L5njjEruLLho9JnSw2O
>> LV0%2BO%2BnR5c%3D&reserved=0>
> >
> > [snip]
>> The default behaviour of http connector is listenning all interfaces.
>
> False.
>
>> It is found in the description of "address" in attributes section.
>> (https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Ftom
>> cat.apache.org%2Ftomcat-9.0-doc%2Fconfig%2Fhttp.html%23SSL_Support&
>> ;data=05%7C01%7CAmit.Pande%40veritas.com%7C13ea9fddeb604e4b7dca08dad19
>> 78243%7Cfc8e13c0422c4c55b3eaca318e6cac32%7C0%7C0%7C638052745907718347%
>> 7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik
>> 1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&sdata=p3R8MryiKpauAppYJLbrGLP
>> FzIUJpONDxvQj%2BlYepnI%3D&reserved=0)
> It's listed in another section, and does not say all interfaces.
>
>> In terms of security default, it could be not best practice. In case of unexpected mistakes made by people, default behaviour of exposing the server to every possible network may pose a potential threat on security.
>
> Good thing Tomcat does not default to that configuration.
>
>> CWE-1327: Binding to an Unrestricted IP Address:
>> https://nam12.safelinks.protection.outlook.com/?url=https%3A%2F%2Fcwe.
>> mitre.org%2Fdata%2Fdefinitions%2F1327.html&data=05%7C01%7CAmit.Pan
>> de%40veritas.com%7C13ea9fddeb604e4b7dca08dad1978243%7Cfc8e13c0422c4c55
>> b3eaca318e6cac32%7C0%7C0%7C638052745907718347%7CUnknown%7CTWFpbGZsb3d8
>> eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3
>> 000%7C%7C%7C&sdata=pZzdfOpc0Cw5kVThNxWZLBZIoW4xXQSoSldTtMn6OEM%3D&
>> amp;reserved=0
>>
>> The issue should be a security enhancement. I recommend changing default behaviour to a single interface/network, e.g loopback interface 127.0.0.1 and adding configuration option with default value OFF for 0.0.0.0 or : :.
>
> Sounds great. So what exactly needs to be changed? You want us to pick only IPv4 or IPv6?
>
> If not, what you describe is exactly the default configuration that you will get.
>
> -chris
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
>
> ---------------------------------------------------------------------
> To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
> For additional commands, e-mail: users-help@tomcat.apache.org
>
---------------------------------------------------------------------
To unsubscribe, e-mail: users-unsubscribe@tomcat.apache.org
For additional commands, e-mail: users-help@tomcat.apache.org