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| ubuntu1604:3:2:1 [2017/05/02 12:49] – utworzono Piotr Kłoczewski | ubuntu1604:3:2:1 [2017/05/03 16:01] (current) – [Remediation] Piotr Kłoczewski |
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| =====Rationale===== | =====Rationale===== |
| Setting ""net.ipv4.conf.all.accept_source_route" and "net.ipv4.conf.default.accept_source_route" to 0 disables the system from accepting source routed packets. Assume this system was capable of routing packets to Internet routable addresses on one interface and private addresses on another interface. Assume that the private addresses were not routable to the Internet routable addresses and vice versa. Under normal routing circumstances, an attacker from the Internet routable addresses could not use the system as a way to reach the private address systems. If, however, source routed packets were allowed, they could be used to gain access to the private address systems as the route could be specified, rather than rely on routing protocols that did not allow this routing. | Setting ''net.ipv4.conf.all.accept_source_route'' and ''net.ipv4.conf.default.accept_source_route'' to 0 disables the system from accepting source routed packets. Assume this system was capable of routing packets to Internet routable addresses on one interface and private addresses on another interface. Assume that the private addresses were not routable to the Internet routable addresses and vice versa. Under normal routing circumstances, an attacker from the Internet routable addresses could not use the system as a way to reach the private address systems. If, however, source routed packets were allowed, they could be used to gain access to the private address systems as the route could be specified, rather than rely on routing protocols that did not allow this routing. |
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| =====Audit===== | =====Audit===== |
| Run the following command and verify output matches: | Run the following command and verify output matches: |
| <Code:bash> | <Code:bash> |
| # sysctl net.ipv4.conf.all.accept_source_route net.ipv4.conf.all.accept_source_route = 0 | # sysctl net.ipv4.conf.all.accept_source_route |
| # sysctl net.ipv4.conf.default.accept_source_route net.ipv4.conf.default.accept_source_route = 0 | net.ipv4.conf.all.accept_source_route = 0 |
| | # sysctl net.ipv4.conf.default.accept_source_route |
| | net.ipv4.conf.default.accept_source_route = 0 |
| </Code> | </Code> |
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| =====Remediation===== | =====Remediation===== |
| Set the following parameter in the "/etc/sysctl.conf" file: | Set the following parameter in the ''/etc/sysctl.conf'' file: |
| <Code:bash> | <Code:bash> |
| net.ipv4.conf.all.accept_source_route = 0 | net.ipv4.conf.all.accept_source_route = 0 |