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Linux Security Cookbook
book

Linux Security Cookbook

by Daniel J. Barrett, Richard E. Silverman, Robert G. Byrnes
June 2003
Intermediate to advanced content levelIntermediate to advanced
336 pages
8h 54m
English
O'Reilly Media, Inc.
Content preview from Linux Security Cookbook

2.8. Blocking Access to a Remote Host

Problem

You want to block outgoing traffic to a particular host.

Solution

To block all access:

For iptables :

# iptables -A OUTPUT -d remote_IP_address -j REJECT

For ipchains :

# ipchains -A output -d remote_IP_address -j REJECT

To block a particular service, such as a remote web site:

For iptables:

# iptables -A OUTPUT -p tcp -d remote_IP_address --dport www -j REJECT

For ipchains:

# ipchains -A output -p tcp -d remote_IP_address --dport www -j REJECT

Discussion

Perhaps you’ve discovered that a particular web site has malicious content on it, such as a trojan horse. This recipe will prevent all of your users from accessing that site. (We don’t consider “redirector” web sites, such as http://www.anonymizer.com, which would get around this restriction.)

See Also

iptables(8), ipchains(8).

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Publisher Resources

ISBN: 0596003919Errata Page