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11 Cards in this Set
- Front
- Back
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What's the generic structure of the IP Tables command line?
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iptables -t tabletype <action direction> <packet pattern> -j
<what to do> |
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iptables -t <tabletype>
What are the three options for <tabletype>? |
filter - drop the packet
nat - change the IP information mangle - change the IP header |
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what is the default table type for the iptables command?
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filter
iptables -t filter |
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iptables -t tabletype <action direction> <packet pattern> -j
<what to do> What is the <action direction> field, and what options are availabe? |
Tells the kernel what type of manipulation you're going to perform on the chain of firewall rules in the kernel.
■ -D (--delete) Deletes a rule from a chain. Specify the rule by the number or the packet pattern. ■ -L (--list) Lists the currently configured rules in the chain. ■ -F (--flush) Flushes all of the rules in the current iptables chain. ■ -A (--append) Appends a rule to the end of a chain. |
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What are the default chains/buckets that iptables places firewall rules into?
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1) INPUT - All incoming packets are checked against the rules in this chain.
2) OUTPUT - All outgoing packets are checked against the rules in this chain. 3) FORWARD - All packets being sent to another computer are checked against the rules in this chain |
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iptables -t tabletype <action direction> <packet pattern> -j <what to do>
What does <packet pattern> match, and what it's purpose? |
■ -s ip_address All packets are checked for a specific source IP address.
■ -d ip_address All packets are checked for a specific destination IP address. |
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Where do you document iptables rules you want inserted at startup on a RHEL 6 system?
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/etc/sysconfig/iptables file
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What is the /etc/sysconfig/iptables-config file used for, and when would you edit it?
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Contains configuration switches that alter the IP Tables kernel module on start-up.
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What are the default rules installed on a RHEL 6 system? and where are these rules kept?
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find these rules in the /etc/sysconfig/iptables files
:INPUT ACCEPT [0:0] :FORWARD ACCEPT [0:0] :OUTPUT ACCEPT [0:0] -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT -A INPUT -p icmp -j ACCEPT -A INPUT -i lo -j ACCEPT -A INPUT -m state --state NEW -m tcp -p tcp --dport 22 -j ACCEPT -A INPUT -j REJECT --reject-with icmp-host-prohibited -A FORWARD -j REJECT --reject-with icmp-host-prohibited |
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What's the best way to roll-out a deployment of iptables rules, and why?
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rpm that modifies the /etc/sysconfig/iptables file. Don't use the custom-rule capability in GUI - it erases and wipes out everything.
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What is the xinetd service?
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The xinetd (also known as the Extended Internet Services Daemon) service can
start a number of server daemons simultaneously. The xinetd service listens for connection requests for all active servers with scripts in the /etc/xinetd.d directory. There’s a generic configuration file for xinetd services, /etc/xinetd.conf. The scripts in the /etc/xinetd.d directory function as service-specific configuration files. |
