Kernel: ip_conntrack: Table full, dropping packet.

There is a problem with a download server today, and packet loss is very serious. After restarting, check the system logs. Many "kernel: ip_conntrack: Table full, dropping packet ."

Search online and solve it with hping

Download hping:
Http://www.hping.org/download.html

./Configure
Make
Make install

After installation, write a script:

Code:

#! /Bin/bash

Echo
Echo "############################"
Echo "# edit by youngh 2003.06.24 V1.1"
Echo "# usage: clr_conns IPaddress"
Echo "# This will clear all connections from this ip_address"
Echo "# example:/root/clr_conns 10.0.3.3"
Echo "############################"
Echo

If [-Z $1]; then
Exit
Fi

Grep-e "^ TCP. {10, 25} established src = $1"/proc/NET/ip_conntrack | while read line; do
S_ip = 'echo $ Line | awk' {print substr ($5, 5 )}''
S_sock = 'echo $ Line | awk '{print substr ($7, 7 )}''
D_ip = 'echo $ Line | awk' {print substr ($6, 5 )}''
D_sock = 'echo $ Line | awk '{print substr ($8, 7 )}''
Echo "$ s_ip: $ s_sock $ d_ip: $ d_sock"

Hping2 $ d_ip-r-s $ s_sock-p $ d_sock-A $ s_ip-K-C 1>/dev/null 2>/dev/null &

Done

Save as clr_conns.sh

Usage:

Sh clr_conns.sh x. x

The displayed connection can be cleared.

From: China Linux Forum

 

View the first IP addresses of ip_conntrack

CAT/proc/NET/ip_conntrack | cut-D ''-f 10 | cut-d' = '-F 2 | sort | uniq-c | sort-Nr | head-n 5