Hello all,
I have a strange problem where some TLS connections are delayed by 30
seconds when going through my transparent proxy with WCCP. This occurs
typically with sites behind Cloudflare (for example,
https://www.wireshark.org). No problem for Google websites for example.
I only want to log the SNI hostname, I do *not* want to
intercept/decrypt/re-encrypt connections with fake certificates.
Here is the setup:
- Linux Debian 7
- OpenSSL 1.0.1t
- Squid 3.5.23 (also tested Squid 4.0.17).
The Squid configure options are:
./configure --enable-delay-pools --with-large-files --enable-async-io
--enable-icmp --enable-kill-parent-hack
--enable-htpc --enable-forw-via-db --enable-cache-digests
--enable-dl-malloc --with-large-files
--enable-linux-netfilter --enable-ssl --enable-ssl-crtd --with-openssl
IPTables configuration (the routing device sending WCCP frames is a
Cisco ASA):
iptables -t nat -A PREROUTING -i wccp0 -p tcp -m tcp --dport 443 -j DNAT
--to-destination 195.83.155.53:3130
The output/public interface is eth0, the traffic returns to clients
through eth1 with the following:
iptables -t mangle -A OUTPUT -p tcp --sport 3130 -j MARK --set-mark 900
ip rule add fwmark 900 table 1
(The table 1 allows direct access to client networks with the
appropriate routes, this is needed because the return traffic must not
go through the ASA).
The SQUID configuration:
https_port 3130 intercept ssl-bump cert=/usr/local/squid/etc/proxyCA.pem
acl step1 at_step SslBump1
acl step2 at_step SslBump2
ssl_bump peek step1 all
ssl_bump splice step2 all
sslcrtd_program /usr/local/squid/libexec/ssl_crtd -s
/usr/local/squid/var/ssl_db -M 40MB
sslcrtd_children 5
wccp2_service dynamic 70 password=XXXXXXXXX
wccp2_service_info 70 protocol=tcp flags=src_ip_hash,dst_ip_hash
priority=240 ports=443
Even if I use only "ssl_bump splice all" the 30-second delay happens.
I have an example of captured traffic here, on the client and the
various network interfaces on the proxy server:
http://www.utc.fr/filex/get?k=6Dt169xGsHMswCKEF5L
As you can see in the captures, Squid returns the "Server Hello" 30
seconds (in cap_eth1.cap) after it has received it from the server (in
cap_eth0.cap).
This behavior is not systematic, sometimes the data is returned
immediately. What could cause this delay ? This looks like some timeout,
but for what reason ?
Thanks in advance for any suggestion !
Christophe
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