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Full disclosure |
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IT Security and Insecurity Portal |
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Apache |
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 Posted: Thu May 20, 2004 10:33 pm |
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| Stonecold |
| Regular user |
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| Joined: May 20, 2004 |
| Posts: 10 |
| Location: Virginia |
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http://moorer-software.com/apache.htm
Link above has more information. I have tried many things on my server to prevent this particular attack, but the only thing that seems to work is to be in SSH at the time of the attack to ban the IP. Any ideas on a solution to prevent this? All of the solutions in that article were used beforehand. I have a copy program if anyone is interested in testing it out. |
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| Posted: Fri May 21, 2004 10:42 am |
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| waraxe |
| Site admin |
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| Joined: May 11, 2004 |
| Posts: 2407 |
| Location: Estonia, Tartu |
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There is one more issue - if you use a firewall and/or IDS to detect DoS flood packets and have them automatically banning source ip addresses, think about what happens when attackers spoof millions of ip addresses and after that nobody can connect to your server.
This scenario is discussed on various firewall manuals and there is no simple solution... |
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| Posted: Fri May 21, 2004 11:00 am |
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| icenix |
| Advanced user |
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| Joined: May 13, 2004 |
| Posts: 106 |
| Location: Australia |
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What type of attack?
if its SYN Flooding, with a bit of luck he will get tired of it...
if not there are some firewall rules that can just stop it all together...but ill have to ask my linux mate.. ill get back to you on it.
SYN flooding is a bitch but also effective  |
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| Posted: Fri May 21, 2004 11:09 am |
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| waraxe |
| Site admin |
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| Joined: May 11, 2004 |
| Posts: 2407 |
| Location: Estonia, Tartu |
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| In general, I am against any DoS attack and think that it is lame to use them. Only normal reason to use DoS is, if you are trying some clever hack attack and you need to knock out one or more of the machines for some time. |
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hrmm |
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| Posted: Fri May 21, 2004 11:12 am |
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| icenix |
| Advanced user |
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| Joined: May 13, 2004 |
| Posts: 106 |
| Location: Australia |
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DoS in itself is just a spastic hack.
anyone could do it and thats just what pisses me off..
if i could change 1 thing about the way DoS or anything else works it would be:
A: for all source codes (.c and .perl) BREAK UP the script so people cant use it
B: NEVER get anyone to compile a DoS tool into an .exe so some loser can use it.
im sure that would greatly reduce the ammount of people who do these things |
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| Posted: Fri May 21, 2004 9:14 pm |
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| Stonecold |
| Regular user |
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| Joined: May 20, 2004 |
| Posts: 10 |
| Location: Virginia |
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Yeah I have done lots of things to prevent syn flooding on my server. The only real fix is going to have to come from Apache it seems like.
echo 1 > /proc/sys/net/ipv4/tcp_syncookies shifts the load more towards the kernel and less towards apache. This helps out some.
Below is part of a bash script I also use:
| Code: | #Reduce DoS'ing ability by reducing timeouts
echo 30 > /proc/sys/net/ipv4/tcp_fin_timeout
echo 1800 > /proc/sys/net/ipv4/tcp_keepalive_time
echo 1 > /proc/sys/net/ipv4/tcp_window_scaling
echo 0 > /proc/sys/net/ipv4/tcp_sack
echo 1280 > /proc/sys/net/ipv4/tcp_max_syn_backlog
#ANTISPOOFING
for a in /proc/sys/net/ipv4/conf/*/rp_filter;
do
echo 1 > $a
done
### chains to DROP too many SYN-s ######
/sbin/iptables -N syn-flood
/sbin/iptables -A syn-flood -m limit --limit 100/second --limit-burst 150 -j RETURN
/sbin/iptables -A syn-flood -j LOG --log-prefix "SYN flood: "
/sbin/iptables -A syn-flood -j DROP |
| Quote: | | if its SYN Flooding, with a bit of luck he will get tired of it... |
The server I use for hosting sites has not been a target luckily. Only servers that seem to get hit are ones that host "Yahoo Booter" sites, as this apache program has been passed around the Yahoo Messenger community. |
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