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Chapter 4
Transparent Proxy Caching
Static bypass rules
In addition to adaptively learning what to bypass, Traffic Server allows you to manually configure bypass rules
to direct requests from certain clients or to particular origin servers around Traffic Server.
For example, you might want client IP addresses that did not pay for a caching service to be steered around
the cache, while paying clients can obtain the benefits of caching. Or you might wish to remove some servers
from caching lists because they do not want to have their pages cached.
You can configure three types of static bypass rules:
•
Source bypass, where Traffic Server bypasses a particular source IP address or range of IP addresses. For
example, you can use this solution to bypass clients who want to opt out of a caching solution.
•
Destination bypass, where Traffic Server bypasses a particular destination IP address or range of IP
addresses. For example, these could be origin servers who use IP authentication based on the client’s real
IP address. Destination bypass rules prevent Traffic Server from caching an entire site. You will
experience hit rate impacts if the site you bypass is popular.
•
Source/destination pair bypass, where Traffic Server bypasses requests that originate from the specified
source to the specified destination. For example, you could route around specific client-server pairs that
experience broken IP authentication or out of band HTTP traffic problems when cached.
Source/destination bypass rules might be preferable to destination rules because they block a destination
server only for those particular users that experience problems.
To configure static bypass rules, edit the
bypass.config
file (refer to
bypass.config‚ on page 161
).
Viewing the current set of bypass rules
The ARM has a supporting utility called
print_bypass
that allows you to view the current dynamic and
static bypass rules.
To view all current dynamic and static bypass rules:
1. Telnet into the HP web cache appliance and select Shell Access as described in
Overview of Access
Methods‚ on page 7
.
2. Enter the following command at the prompt and press Return:
print_bypass
All current static and dynamic bypass rules display on screen. The rules are sorted by IP address. You can
direct the output of
print_bypass
to a file and save it.
Configuring ARM security
To prevent unauthorized access to machines running Traffic Server, you can configure the ARM to utilize an
access control list employing administrator-specified rules to either allow or deny other computers from
communicating with the machine. This enables you to effectively create a firewall in front of Traffic Server,
thereby denying potentially malicious packets from even reaching the TCP/IP stack on the machine. Refer to
Controlling host access to the Traffic Server machine (ARM security)‚ on page 81
.
