On 04/01/18 14:09, John Ratliff wrote:
On 1/3/2018 3:26 PM, Antony Stone wrote:
On Wednesday 03 January 2018 at 21:06:42, John Ratliff wrote:
When I try to setup squid as a transparent proxy, I never get any
response from Squid.
When I try a wget request from a server that is being redirected
How (and more importantly, where) are you doing the redirect?
Both machines are behind the same firewall. I used
iptables -t nat -A PREROUTING -p tcp --dport 80 -j DNAT --to
10.77.9.120:3128
If that firewall is not on the machine running Squid, then that's your
problem.
Traffic flows to the server running squid. I can verify this with
tcpdump. The packets are making it from wget to the server. I just don't
know what happens after that.
https://wiki.squid-cache.org/ConfigExamples/Intercept/LinuxRedirect
"NOTE: This configuration is given for use *on the squid box*. This is
required
to perform intercept accurately and securely. To intercept from a gateway
machine and direct traffic at a *separate squid box* use policy routing."
https://wiki.squid-cache.org/ConfigExamples/Intercept/IptablesPolicyRoute
Antony.
Thanks. I put squid on the firewall itself. It works for http, but not
for https. I get errors with curl and wget.
$ curl https://debian.org
curl: (35) error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown
protocol
$ wget https://debian.org
--2018-01-03 20:02:45-- https://debian.org/
Resolving debian.org (debian.org)... 5.153.231.4, 128.31.0.62,
130.89.148.14, ...
Connecting to debian.org (debian.org)|5.153.231.4|:443... connected.
GnuTLS: An unexpected TLS packet was received.
Unable to establish SSL connection.
I made some config changes:
http_port 3128 intercept
http_port 3129 intercept ssl-bump generate-host-certificates=on
cert=/etc/squid/squid.pem
That should be:
https_port 3129 intercept ssl-bump generate-host-certificates=on \
cert=/etc/squid/squid.pem
Note the 's' in https_port.
sslcrtd_program /usr/lib/squid/ssl_crtd -s /var/lib/ssl_db -M 4MB
ssl_bump bump all
This instructs Squid to bump before even receiving the client TLS
handshake - ie. generate a server certificate with zero details to work
with about what the client wants.
That leads to a LOT of problems and security issues. Please do not do that.
See <https://wiki.squid-cache.org/Features/SslPeekAndSplice> for better
config examples.
Here are my PREROUTING nat table rules.
REDIRECT tcp -- 10.77.9.0/24 anywhere tcp dpt:http redir ports 3128
REDIRECT tcp -- 10.77.9.0/24 anywhere tcp dpt:https redir ports 3129
And in the INPUT chain of the filter table:
ACCEPT tcp -- 10.77.9.0/24 anywhere tcp dpt:3128
ACCEPT tcp -- 10.77.9.0/24 anywhere tcp dpt:3129
The server I am on has IP 10.77.9.102.
You appear to be missing the MASQUERADE rule to send packets back to the
client.
Also the mangle table (*not* filter) rules are important to block
external traffic directly to those Squid ports without interfering with
the NAT operations.
<https://wiki.squid-cache.org/ConfigExamples/Intercept/LinuxRedirect>
Amos
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