Linux Ask! is a Q & A web site specific for Linux related questions. Questions are collected, answered and audited by experienced Linux users.
Check the number of active Apache connection
Answer:
When your Apache server is overloaded, you might want to check how many active connections are there.
# netstat -anpt|grep apache2 |grep ESTABLISHED
Replace apache2 with httpd if you are using CentOS/Fedora/RHEL.
Check for the number of connection from a particular IP address
Answer:
You can check the total number of connections from a particular IP address:
# netstat -ntu | awk '{print $5}'| cut -d: -f1 | sort | uniq -c | sort -nr | more
It will give something like:
25 192.168.1.2
13 192.168.1.3
..
mount: unknown filesystem type 'nfs'
Answer:
If you attempt to mount a NFS share, using the mount command, e.g.
# sudo mount -t nfs 192.168.1.2:/data/share /mnt/share
And it gives:
mount: unknown filesystem type 'nfs'
You would need to install the nfs clients to solve it:
# sudo apt-get install nfs-common
How to kill a TCP connection using tcpkill?
Answer:
You can use the tcpkill program.
tcpkill came with the dsniff in Debian/Ubuntu, you need to install it manually.
# sudo apt-get install dsniff
Usages:
1. Kill all outgoing web (port 80) connection:
# tcpkill -i eth0 port 80
2. Kill all connection by IP
# tcpkill -i eth0 host www.google.com
Downgrade the format of a Subversion working copy
Answer:
Sometimes, when you upgraded the local subversion working copy, but others use an older client to access it, error likes "This client is too old to work with working copy..." will appear.
To fix this, you can consider downgrade the format of the subversion working copy.
E.g. Downgrade to 1.4
# change-svn-wc-format.py /path/to/working/copy 1.4
The useful python script can be downloaded here: http://svn.apache.org/repos/asf/subversion/trunk/tools/client-side/change-svn-wc-format.py
