Using modern Protocols like HTTP/2 and QUIC

First there was HTTP, then HTTP/2 and now HTTP/2 over the QUIC protocol. Lets have a look at the available HTTP Clients and Servers that support HTTP/2 and the experimental QUIC protocol.

Introduction

The Hypertext Transfer Protocol (HTTP) was invented in 1991. Up to 2015 then there was only little to no evolution. In 2015 the HTTP/2 protocol was defined as a standard. HTTP/2 is much more efficient that its ancestors.

It features multiplexing, stream prioritization, binary transmission and much more. Its a huge step forward.

Nevertheless, there is a need for something more efficient. HTTP/2 is using TCP (Transmission Control Protocol) which was created in the early days of the Internet to have a reliable connection over unreliable networks. Today’s networks are much more reliable which allows the usage of the unreliable but very efficient UDP (User Datagram Protocol) to transmit data. As a consequence, QUIC was born. It is using UDP instead of TCP.

QUIC includes the crypto layer, so there is no need of a separate TLS layer. The goal is to use TLS 1.3 which is not ready as of writing this post.

Both, QUIC and TLS 1.3 are currently being defined as standards, the current state of the TLS Working group is publish here, the work of the QUIC working group is vailable here.

A good overview about QUIC can be found here.

Client Software

As of writing this post, all major Browsers are supporting HTTP/2 over TCP. When it comes to QUIC, there is little left. At the moment only Chrome and Opera are capable to access web sites with QUIC.

It is expected that this will change as soon as the standard is finalized.

Web sites

I’m not aware of any prominent Website using QUIC beside of google. HTTP/2 is used by a lot of prominent sites such as facebook, google and many others.

Server Software

The situation for HTTP/2 looks good, most webservers such as Apache HTTPD, NGINX etc. come with support for HTTP/2. Well, Apache does not work with the prefork MPM, that means you can not use mod_php with HTTP/2. You can make use of FastCGI but this means that Apache will be the slowest webserver available on the market. Better use NGINX.

If it comes to QUIC support, there is an experimental NGINX module available. Unfortunately it seems to be abandoned.

An option could be the commercial LiteSpeed Server.

From my point of view, the only usable Webserver for both, HTTP/2 and QUIC is Caddy. Its a relatively new open source project implementing a lot of new and experimental technologies. A nice feature is automatic HTTPS with Letsencrypt.

Caddy Webserver

Lets have a closer look to Caddy on Fedora 27. Its quite straight forward to install and configure.

Installation

[root@f27 ~]# dnf install caddy certbot

Configuration

cat > /etc/caddy/caddy.conf << EOF
:80 {
    gzip
    root /usr/share/caddy
}
EOF

Get a Letsencrypt Certficate

[root@f27 ~]# certbot certonly
Saving debug log to /var/log/letsencrypt/letsencrypt.log

How would you like to authenticate with the ACME CA?
-------------------------------------------------------------------------------
1: Spin up a temporary webserver (standalone)
2: Place files in webroot directory (webroot)
-------------------------------------------------------------------------------
Select the appropriate number [1-2] then [enter] (press 'c' to cancel): 2
Plugins selected: Authenticator webroot, Installer None
Please enter in your domain name(s) (comma and/or space separated)  (Enter 'c'
to cancel): f27.ldelouw.ch
Obtaining a new certificate
Performing the following challenges:
http-01 challenge for f27.ldelouw.ch
Input the webroot for f27.ldelouw.ch: (Enter 'c' to cancel): /usr/share/caddy/
Waiting for verification...
Cleaning up challenges

IMPORTANT NOTES:
 - Congratulations! Your certificate and chain have been saved at:
   /etc/letsencrypt/live/f27.ldelouw.ch/fullchain.pem
   Your key file has been saved at:
   /etc/letsencrypt/live/f27.ldelouw.ch/privkey.pem
   Your cert will expire on 2018-05-31. To obtain a new or tweaked
   version of this certificate in the future, simply run certbot
   again. To non-interactively renew *all* of your certificates, run
   "certbot renew"

Configure TLS

cat >> /etc/caddy/caddy.conf << EOF
:443 {
    gzip
    root /usr/share/caddy
    tls /etc/letsencrypt/live/f27.ldelouw.ch/fullchain.pem /etc/letsencrypt/live/f27.ldelouw.ch/privkey.pem
}

EOF

Give the caddy user access to the cert and key

[root@f27 ~]# setfacl -m u:caddy:r-X /etc/letsencrypt/live

Enable QUIC

[root@f27 ~]# cp /usr/lib/systemd/system/caddy.service /etc/systemd/system/
[root@f27 ~]# sed -i 's#ExecStart=/usr/bin/caddy -conf /etc/caddy/caddy.conf -log stdout -root /tmp -agree#ExecStart=/usr/bin/caddy -conf /etc/caddy/caddy.conf -log stdout -root /tmp -agree -quic#g' /etc/systemd/system/caddy.service
[root@f27 ~]# systemctl daemon-reload
[root@f27 ~]# systemctl restart caddy

Checking the Result

Enabling QUIC in your brower

Point Chrome to chrome://flags/ and search for QUIC. Enable it and relaunch the browser.

Open Chrome and a second tab with chrome://net-internals/#quicType the URL, i.e. https://f27.ldelouw.ch. Switch the to chrome tab and see the Result.

QUIC Screenhot

QUIC Screenhot

Blueborne – How to disable Bluetooth in Fedora

Yesterday 2017-09-13 Redhat released infomation about the mitigation of the Blueborne vulnerability in RHEL: https://access.redhat.com/security/vulnerabilities/blueborne.

For Fedora the new updates are probably still in the build queue and/or being QAed by the community. For a quick fix, you can disable Bluetooth similar than in RHEL:

Stopping Bluetooth related service

systemctl stop bluetooth.service
systemctl disable bluetooth.service
systemctl mask bluetooth.service

Disable the Kernel modules

echo "install bnep /bin/true" >> /etc/modprobe.d/disable-bluetooth.conf
echo "install bluetooth /bin/true" >> /etc/modprobe.d/disable-bluetooth.conf
echo "install btusb /bin/true" >> /etc/modprobe.d/disable-bluetooth.conf
echo "install btintel /bin/true" >> /etc/modprobe.d/disable-bluetooth.conf
echo "install btrtl /bin/true" >> /etc/modprobe.d/disable-bluetooth.conf
echo "install btbcm /bin/true" >> /etc/modprobe.d/disable-bluetooth.conf

Removing the Kernel Modules from a running System

  rmmod bnep
  rmmod btusb
  rmmod btintel
  rmmod btrtl
  rmmod btbcm
  rmmod bluetooth

Configure SSSD to work on IPv6-only Hosts

SSSD is used for the client side of IPA and other centralized Identity Management Services. Unfortunately it does not behave as it should. The default is to look up first IPv4 addresses and if that fails IPv6 should be used. Well, if IPv4 fails, the whole request fails and you got weird error messages when joining an IPA domain.

As the pool for IPv4 addresses is depleted, IPv6 is getting more and more important. Thus, IPv6-only hosts are on the rise.

Here is an example error message from the IPA client.

[root@ipv6host ~]# ipa-client-install
[output ommited] 
SSSD enabled
Configured /etc/openldap/ldap.conf
Unable to find 'admin' user with 'getent passwd admin@example.com'!
Unable to reliably detect configuration. Check NSS setup manually.
[output ommited]

The host itself gets properly joined to the IPA domain and authentication works with Kerberos but you can not log in because SSSD fails.

Workaround

Configure SSSD to only use IPv6. This is done in /etc/sssd/sssd.conf

[domain/example.com]
lookup_family_order = ipv6_only
cache_credentials = True
krb5_store_password_if_offline = True
ipa_domain = example.com
id_provider = ipa
auth_provider = ipa
access_provider = ipa
ipa_hostname = ipv6host.example.com
chpass_provider = ipa
ipa_server = _srv_, ipa1.example.com
ldap_tls_cacert = /etc/ipa/ca.crt
[sssd]
services = nss, sudo, pam, ssh

domains = example.com
[nss]
homedir_substring = /home

[pam]

[sudo]

[autofs]

[ssh]

[pac]

[ifp]

Solution

At the moment there is no solution yet (just the workaround described), but its addressed at the SSSD project team, as you can see in https://pagure.io/SSSD/sssd/issue/2128 and https://bugzilla.redhat.com/show_bug.cgi?id=1021435

Happy IPv6-ing 🙂