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IBM Tivoli Access Manager for e-business: WebSEAL Administration ...

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Suppressing<br />

server<br />

identity<br />

HTTP<br />

server<br />

responses<br />

normally<br />

contain<br />

the<br />

identity<br />

and<br />

version<br />

of<br />

the<br />

server:<br />

content-type:<br />

text/html<br />

date:<br />

Tue,<br />

05<br />

Mar<br />

2002<br />

02:34:18<br />

GMT<br />

content-length:<br />

515<br />

server:<br />

<strong>WebSEAL</strong>/3.9.0<br />

last-modified:<br />

Thu,<br />

21<br />

Feb<br />

2002<br />

08:03:46<br />

GMT<br />

connection:<br />

close<br />

For<br />

security<br />

reasons,<br />

you<br />

might<br />

want<br />

<strong>WebSEAL</strong><br />

to<br />

suppress<br />

this<br />

in<strong>for</strong>mation<br />

in<br />

its<br />

responses<br />

to<br />

clients.<br />

To<br />

suppress<br />

server<br />

identity<br />

in<br />

HTTP<br />

server<br />

responses,<br />

set<br />

the<br />

suppress-server-identity<br />

parameter<br />

in<br />

the<br />

[server]<br />

stanza<br />

of<br />

the<br />

<strong>WebSEAL</strong><br />

configuration<br />

file<br />

to<br />

″yes″:<br />

[server]<br />

suppress-server-identity<br />

=<br />

yes<br />

The<br />

default<br />

setting<br />

is<br />

″no″.<br />

Handling<br />

BASE<br />

HREF<br />

tags<br />

You<br />

can<br />

configure<br />

how<br />

<strong>WebSEAL</strong><br />

handles<br />

BASE<br />

HREF<br />

tags<br />

from<br />

filtered<br />

HTML<br />

documents.<br />

In<br />

the<br />

<strong>WebSEAL</strong><br />

configuration<br />

file,<br />

use<br />

the<br />

preserve-base-href<br />

setting<br />

to<br />

specify<br />

the<br />

behavior:<br />

[server]<br />

preserve-base-href<br />

=<br />

no<br />

When<br />

preserve-base-href<br />

is<br />

set<br />

to<br />

no,<br />

<strong>WebSEAL</strong><br />

removes<br />

all<br />

BASE<br />

HREF<br />

tags<br />

from<br />

filtered<br />

HTML<br />

documents<br />

and<br />

prepends<br />

the<br />

base<br />

tag<br />

to<br />

filtered<br />

links.<br />

When<br />

preserve-base-href<br />

is<br />

set<br />

to<br />

yes,<br />

the<br />

BASE<br />

HREF<br />

tag<br />

is<br />

filtered.<br />

Enabling<br />

HTTP<br />

TRACE<br />

method<br />

RFC<br />

2616<br />

<strong>for</strong><br />

HTTP<br />

defines<br />

a<br />

TRACE<br />

method<br />

as<br />

follows<br />

″This<br />

method<br />

is<br />

used<br />

to<br />

invoke<br />

a<br />

remote,<br />

application-layer<br />

loopback<br />

of<br />

the<br />

requested<br />

message.<br />

The<br />

recipient<br />

of<br />

the<br />

request<br />

is<br />

either<br />

the<br />

origin<br />

server<br />

or<br />

the<br />

first<br />

proxy<br />

or<br />

gateway<br />

to<br />

receive<br />

a<br />

Max-Forwards<br />

value<br />

of<br />

zero<br />

(0)<br />

in<br />

the<br />

request.″<br />

The<br />

TRACE<br />

method<br />

has<br />

been<br />

used<br />

by<br />

hackers<br />

to<br />

implement<br />

a<br />

security<br />

attack<br />

on<br />

Web<br />

servers.<br />

To<br />

provide<br />

optimal<br />

security,<br />

<strong>WebSEAL</strong><br />

by<br />

default<br />

blocks<br />

the<br />

TRACE<br />

method<br />

<strong>for</strong><br />

all<br />

requests<br />

to<br />

the<br />

<strong>WebSEAL</strong><br />

server.<br />

You<br />

can<br />

enable<br />

the<br />

TRACE<br />

method<br />

(disable<br />

blocking)<br />

by<br />

setting<br />

two<br />

entries<br />

in<br />

the<br />

<strong>WebSEAL</strong><br />

configuration<br />

file.<br />

To<br />

enable<br />

TRACE<br />

methods<br />

<strong>for</strong><br />

local<br />

responses,<br />

set<br />

the<br />

following<br />

entry:<br />

[server]<br />

http-method-trace-enabled<br />

=<br />

yes<br />

To<br />

enable<br />

TRACE<br />

methods<br />

<strong>for</strong><br />

junctioned<br />

responses,<br />

set<br />

the<br />

following<br />

entry:<br />

[server]<br />

http-method-trace-enabled-remote<br />

=<br />

yes<br />

The<br />

default<br />

<strong>WebSEAL</strong><br />

configuration<br />

file<br />

does<br />

not<br />

set<br />

any<br />

value<br />

<strong>for</strong><br />

these<br />

configuration<br />

file<br />

entries.<br />

The<br />

default<br />

behavior<br />

<strong>for</strong><br />

<strong>WebSEAL</strong>,<br />

even<br />

when<br />

the<br />

configuration<br />

file<br />

entries<br />

are<br />

not<br />

specified,<br />

is<br />

to<br />

block<br />

all<br />

TRACE<br />

methods.<br />

Chapter<br />

2.<br />

<strong>WebSEAL</strong><br />

server<br />

configuration<br />

69

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