Commands tagged iptables (24)
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Stuck behind a restrictive firewall at work, but really jonesing to putty home to your linux box for some colossal cave? Goodness knows I was...but the firewall at work blocked all outbound connections except for ports 80 and 443. (Those were wide open for outbound connections.) So now I putty over port 443 and have my linux box redirect it to port 22 (the SSH port) before it routes it internally. So, my specific command would be:
iptables -t nat -A PREROUTING -p tcp --dport 443 -j REDIRECT --to-ports 22Note that I use -A to append this command to the end of the chain. You could replace that with -I to insert it at the beginning (or at a specific rulenum). My linux box is running slackware, with a kernel from circa 2001. Hopefully the mechanics of iptables haven't changed since then. The command is untested under any other distros or less outdated kernels. Of course, the command should be easy enough to adapt to whatever service on your linux box you're trying to reach by changing the numbers (and possibly changing tcp to udp, or whatever). Between putty and psftp, however, I'm good to go for hours of time-killing.10iptables -t nat -A PREROUTING -p tcp --dport [port of your choosing] -j REDIRECT --to-ports 22 -
This will allow you to watch as matches occur in real-time. To filter out only ACCEPT, DROP, LOG..etc, then run the following command: watch 'iptables -nvL | grep -v "0 0" && grep "ACCEPT"' The -v is used to do an inverted filter. ie. NOT "0 0"
7watch --interval 0 'iptables -nvL | grep -v "0 0"' -
Removes an iptables rule created by fail2ban. This example shows how to remove a rule for an IP from the fail2ban-SSH chain. Can be used for any service monitored by fail2ban. For more on fail2ban, see http://www.fail2ban.org/wiki/index.php/Main_Page
4iptables -D fail2ban-SSH -s <ip_address_to_be_set_free> -j DROP -
google has added 2 more netblocks... Show Sample Output
4for NETBLOCK in $(echo _netblocks.google.com _netblocks2.google.com _netblocks3.google.com); do nslookup -q=TXT $NETBLOCK ; done | tr " " "\n" | grep ^ip[46]: | cut -d: -f2- | sort -
edit the /etc/sysconfig/iptables file and try to work whit this: -A INPUT -i (interface) -m mac (mac address) -j ACCEPT/DROP
2-A INPUT -i eth1 -m mac ?mac 00:BB:77:22:33:AA -j ACCEPT -
Rather then editing the /etc/sysconfig/iptables file, or during a kickstart doing some awk/sed magic, easily add a rule in the correct place within iptables
1REJECT_RULE_NO=$(iptables -L RH-Firewall-1-INPUT --line-numbers | grep 'REJECT' | awk '{print $1}');/sbin/iptables -I RH-Firewall-1-INPUT $REJECT_RULE_NO -m state --state NEW -m tcp -p tcp --dport 80 -j ACCEPT -m comment --comment "Permit HTTP Service" -
1watch -n1 iptables -vnL
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VPS server hosts suspect DOS attack if PPS is too high. This limits packets at the interface level. Do "sudo apt-get install iptables-persistent" to make persistent, or, if you already have, reconfigure with "sudo dpkg-reconfigure iptables-persistent" Show Sample Output
1sudo iptables -A INPUT -m limit --limit 2000/sec -j ACCEPT && sudo iptables -A INPUT -j DROP -
This turns your iptables packet filter to a "Allow any from any to any" filter, so you can rule out any filtering issues when you have a problem to enable a connection from or to your host. To re-enable it, run /etc/init.d/iptables restart
0iptables -F && iptables -X && iptables -P INPUT ACCEPT && iptables -OUTPUT ACCEPT -
Destination IPs will become invisible to source IPs!
0iptables -A FORWARD -i br0 -m iprange --src-range 192.168.0.x-192.168.0.y -m iprange --dst-range 192.168.0.w-192.168.0.z -j DROP -
a simple command in order to make iptables rules permanent, run @ sudo!
0iptables-save > firewall.conf; rm -f /etc/network/if-up.d/iptables; echo '#!/bin/sh' > /etc/network/if-up.d/iptables; echo "iptables-restore < firewall.conf" >> /etc/network/if-up.d/iptables; chmod +x /etc/network/if-up.d/iptables -
Should run with sudo
0cd /etc/network/if-up.d && iptables-save > firewall.conf && echo -e '#!/bin/sh -e\niptables-restore < $(dirname $0)/firewall.conf' > iptables && chmod a+x iptables -
If you changed the default policy on any chain other than filter table chain's, this won't be enough.
0iptables -P INPUT ACCEPT; iptables -P FORWARD ACCEPT; iptables -P OUTPUT ACCEPT; for table in `cat /proc/net/ip_tables_names`; do iptables -t $table -F; iptables -t $table -Z; iptables -t $table -X; done -
this alternative shows the differences as they occur so that they are made plain Show Sample Output
0while true; do iptables -nvL > /tmp/now; diff -U0 /tmp/prev /tmp/now > /tmp/diff; clear; cat /tmp/diff; mv /tmp/now /tmp/prev; slee p 1; done -
This will highlight (with a box over it) any changes since the last refresh.
0watch -d -n 2 iptables -nvL -
0watch -n1 iptables -vnL
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-A INPUT -p udp -m udp --dport 10000:66000 -m mac --mac-source 3E:D7:88:A6:66:8E -j ACCEPT -A INPUT -p udp -m udp --dport 5060 -m mac --mac-source 3E:D7:88:A6:66:8E -j ACCEPT -A INPUT -p tcp --dport 22 -m mac --mac-source 3E:D7:88:A6:66:8E -j ACCEPT Show Sample Output
0-A INPUT -p tcp --dport 22 -m mac --mac-source 3E:D7:88:A6:66:8E -j ACCEPT -
Block given ip for X seconds and then automatically unban.
0IP=192.168.0.12 DELAY=15 bash -c 'sudo iptables -A INPUT -s ${IP:-badguy.localdomain} -j DROP && echo blocked "$IP" && sudo bash -c "sleep ${DELAY:-600}; iptables -D INPUT -s ${IP:-badguy.localdomain} -j DROP && echo unblocked $IP" 1>&1 & disown %1' -
If you don't save the rule set it won't be applied during a reboot
-1sudo iptables-restore < /etc/iptables.test.rules -
-1iptables -A INPUT -s 65.55.44.100 -j DROP
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display IP's that unsuccessfully attempted to login 5 or more times today may want to filter any trusted IP's and the localhost useful for obtaining a list IP addresses to block on the firewall Show Sample Output
-1lastb -i | grep "$(date '+%a %b %d')" | awk '{ print $3 }' | sort | uniq -c | awk '{ if ($1 >= 5) print $2; }' -
This command will open tcp port 3000 in your machine
-2sudo iptables -I INPUT -p tcp --dport 3000 -j ACCEPT -
Stores the currently active iptables rules to a file that will be applied upon reboot
-3sudo iptables-save > /etc/iptables.up.rules -
To save all rules so that they are not lost in case of a server reboot: /etc/init.d/iptables save
-10iptables -A OUTPUT www.baidu.com -p tcp -j REJECT --reject-with tcp-reset
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