The Juniper PE router must be configured to ignore or block all packets with any IP options.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-254024	JUEX-RT-000520	SV-254024r997532_rule		Medium

Description
Packets with IP options are not fast switched and, therefore, must be punted to the route engine (RE). Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers.

Description

Packets with IP options are not fast switched and, therefore, must be punted to the route engine (RE). Hackers who initiate denial-of-service (DoS) attacks on routers commonly send large streams of packets with IP options. Dropping the packets with IP options reduces the load of IP options packets on the router. The end result is a reduction in the effects of the DoS attack on the router and on downstream routers.

STIG	Date
Juniper EX Series Switches Router Security Technical Implementation Guide	2024-06-10

Details

Check Text ( C-57476r844103_chk )
Review the router configuration to determine if it will block all packets with IP options. [edit firewall family inet] filter { term 1 { from { ip-options any; } then { log; syslog; discard; } } term default { then { log; syslog; discard; } } } [edit interfaces] { unit { family inet { filter input ; address /; } } } Note: Some Juniper devices support both monolithic filters and filter lists. Filter lists separate each term, or set of terms, into a separate filter that is applied sequentially to an interface. If using filter lists, the keywords "input" or "output" change to "input-list" or "output-list". Verify the final list item is a deny-all filter. The deny-all filter is created once per family and can be reused across multiple lists. For example: input-list [ permit_mgt permit_routing_protocols default-deny ]; If the router is not configured to drop all packets with IP options, this is a finding.

Check Text ( C-57476r844103_chk )

Review the router configuration to determine if it will block all packets with IP options.

[edit firewall family inet]
filter {
term 1 {
from {
ip-options any;
}
then {
log;
syslog;
discard;
}
}

term default {
then {
log;
syslog;
discard;
}
}
}
[edit interfaces]
{
unit {
family inet {
filter input ;
address /;
}
}
}

Note: Some Juniper devices support both monolithic filters and filter lists. Filter lists separate each term, or set of terms, into a separate filter that is applied sequentially to an interface. If using filter lists, the keywords "input" or "output" change to "input-list" or "output-list". Verify the final list item is a deny-all filter. The deny-all filter is created once per family and can be reused across multiple lists. For example:

input-list [ permit_mgt permit_routing_protocols default-deny ];

If the router is not configured to drop all packets with IP options, this is a finding.

Fix Text (F-57427r844104_fix)
Configure the router to drop all packets with IP options. set firewall family inet filter term 1 from ip-options any set firewall family inet filter term 1 then log set firewall family inet filter term 1 then syslog set firewall family inet filter term 1 then discard set firewall family inet filter default term 1 then log set firewall family inet filter default term 1 then syslog set firewall family inet filter default term 1 then discard set interfaces unit family inet filter input set interfaces unit family inet address /

Fix Text (F-57427r844104_fix)

Configure the router to drop all packets with IP options.

set firewall family inet filter term 1 from ip-options any
set firewall family inet filter term 1 then log
set firewall family inet filter term 1 then syslog
set firewall family inet filter term 1 then discard

set firewall family inet filter default term 1 then log
set firewall family inet filter default term 1 then syslog
set firewall family inet filter default term 1 then discard

set interfaces unit family inet filter input
set interfaces unit family inet address /