Classic Network Problems in linux

For more information about classic network problems in linux, see Linux Enterprise applications-Linux server applications. 0001

Change apache's default character set to Chinese

If it is 1. *, vi httpd. conf

Find adddefadefacharset ISO8859-1 line, change to adddefacharcharset GB2312

If it is 2. *, you need to change the location, vi httpd. conf

Adddefadefacharset ISO-8859-1 changed to adddefadefacharset off

0002

Change ip address permanently

Ifconfig eth0 new ip

Then edit/etc/sysconfig/network-scripts/ifcfg-eth0 and modify the ip

0003

Remote display of Windows desktop (lnx3000) from Linux)

Install rdesktop package

0004

Manually add Default Gateway

Run the following command as the root user: route add default gw gateway IP Address:

Want to change gateway

1. vi/etc/sysconfig/network-scripts/ifcfg-eth0

Change GATEWAY

2./etc/init. d/network restart

0005

Redhat 8.0 on msn and qq

Put the downloaded plug-in file into the/temp directory, and then delete the existing Gaim in the system. That is, in the terminal simulator, type the command: rpm-e gaim.

Start Installation

Open the terminal simulator and run the following command to install Gaim 0.58:

Cd/temp (go to the temp directory)

Rpm-ivh gaim-0.58-2.i386.rpm (software installation)

After the installation is successful, you can create a Gaim icon on the GNOME or KDE Desktop.

To continue to install the QQ plug-in, enter the following command:

Gunzip libqq-0.0.3-ft-0.58-gcc296.so.gz (Extract files)

Cp libqq-0.0.3-ft-0.58-gcc296.so/usr/lib/gaim (copy the plug-in to the gaim library directory)

Software settings

The logon interface that appears when Gaim 0.85 is started for the first time. Select plug-in first, click load in the plug-in dialog box, load libmsn. so and libqq-0.0.3-ft-0.58-gcc296.so files respectively, confirm and close. Then select "all accounts" and click "add" in the account editor that appears. When the Account Modification page appears, we can enter our QQ or MSN number, enter the QQ number or MSN mailbox for the login name, enter the corresponding QQ or MSN password for the password, enter your nickname for Alias, select the corresponding QQ or MSN protocol, and set other settings to the default one. After all the settings are complete, you can log on and use them.

0006

Find out what program is running on port 22

Lsof-I: 22

0007

View the local IP address, gateway, and dns

IP:

Log on as the root user and execute ifconfig. Eth0 is the first Nic, and lo is the default device.

Gateway:

Log on as a root user and run netstat-rn. the Gateway of a row starting with 0.0.0.0 is the default Gateway. You can also view the/etc/sysconfig/network file, which contains the specified address!

DNS:

More/etc/reslov. conf:

Nameserver 202.96.69.38

Nameserver 202.96.64.38

0008

RH8.0 command line to easily change the ping TTL value (cgweb)

# Sysctl-w net. ipv4.ip _ default_ttl = N

(N = 0 ~ 255). If N> 255, ttl = 0

0009

Easily change the default system configuration value (houaq) in the RH8.0 command line)

Edit/etc/sysctl. conf. For example, Set

Net. ipv4.ip _ forward = 0

Change

Net. ipv4.ip _ forward = 1

It takes effect after restart. Use sysctl-a to view details.

0010

Mount directories shared by other windows machines on the LAN

Mount-t smbfs-o username = guest, password = guest // machine/path/mnt/cdrom

0011

Allowed | Prohibit root login via SSH (Fun-FreeBSD)

Modify sshd_config: PermitRootLogin no | yes

0012

Allow the root user to directly log on via telnet

Edit/etc/pam. d/login and remove

Auth required/lib/security/pam_securetty.so

0013

Connect to the adsl device in linux

The application for a Linux + at least one network card + broadband device that is running normally has been completed, and there are probably several ADSL devices on the market before it is activated. There are some slight differences in the way they work. The process of using virtual dialing to access the Internet, that is, using pppoe devices to perform virtual dialing is called an omnidirectional cat, which is a kind of automatic dialing after power-on, then we leave our interface RJ45,

Generally, the gateways left for us in Dalian are 10.0.0.2. This kind of device is the easiest to deal with. In the end, a fixed IP address is directly allocated to the user, which is easier to deal with than everyone else.

1. The first type requires Dialing:

These devices communicate with the computer through the eth interface. Therefore, connect the hardware device first, especially the broadband cat, be sure to make sure it is correct (otherwise it will not be my business if you want to do it later ). Then start the system and check whether the rp-pppoe software is installed on the system (search by rpm-qa | grep pppoe). If no user is installed, go down one on the CD or on the Internet. After installation, run the adsl-setup command as the root user to enter the configuration status of the adsl data, you need to enter the user name and other information for applying for broadband, confirm that there is no problem, accept until the end (which is all E-text, but can understand at first glance, relatively simple, related to a firewall settings, I generally don't need to use it. Select 0. You can take it into consideration ).

After the configuration is complete, run the adsl-start command as the root user. The adsl dial-up will be launched normally. If you have any specific problems, let's take a look at what the log (/var/log/messages) tells you. Stop adsl and execute adsl-stop (very simple)

2. The other two methods are easier to deal:

Omnidirectional Cat: as long as you set the IP address of your network card to a 10-segment IP address, and then the gateway points to the IP address of the omnidirectional CAT (10.0.0.2), there is basically no big problem.

Fixed IP Address: Just like configuring a local Nic, you can fill in the IP address, gateway, and DNS according to the application.

0014

Automatic linux synchronization time (shunz)

Vi/etc/crontab

Add the following sentence:

00 0 1 ** root rdate-s time.nist.gov

0015

Change telnet port

In the/etc/services file, you can modify the desired port number and restart the daemon.

0016

Terminal Mode problems (sakulagi)

Export TERM = vt100

0017

Imitating a Super Terminal, what programs in LINUX are connected to routers and switches (alstone)

Minicom

0018

Automatically disconnected over ssh (wind521)

That is the timetou setting. Modify the TMOUT variable value.

0019

What tools are used for intrusion detection?

Snort

0020

Tool for detecting program memory leakage in Linux

Both cchecker and efence databases are supported.

0021

How to monitor all data through the local Nic in linux

Tcpdump iptraf

0022

Why does the root user say "command not found" when executing many commands?

You must telnet d TO su root. Change the su command format to su root.

0023

Disable the POP3 permission of a user (tiansgx)

You can turn off the POP3 port. Find the pop-3 110/tcp line in the file/etc/services and add a # line before it. Just comment it out.

0024

Playing flash Animation (myxfc) in linux)

Playing flash Animation in linux will not close the browser (Other plug-ins are not easy to use)

First download the flash Player Plug-in linux

Tar zxvf flash_linux.tar.gz

After opening the package, you will see the Linux folder

In the linux File cheek, there are two files libflashplayer. so and shockwaveflash. class. Copy these two files to the plug-ins in your browser (different browsers may have different plug-ins in different locations)

/Usr/lib/mozilla-1.0.1/plugins, you can

0025

Lock the wu-ftp user directory (wangla)

Edit the ftpaccess File

Restricted-uid *

This sentence is very important, which limits ftp users to be in their own directories.

0026

How can I prevent telnet from the server (Zhiqiu yiye)

The telnet Service and the firewall priority of the server must be set to low.

0027

Prevent anyone from using the su command as root (xiaohu0)

1. vi/etc/pam. d/su

Auth sufficient/lib/security/pam_rootok.so debug

Auth required/lib/security/pam_wheel.so group = wheel

2. Define the wheel group in the/etc/pam. d/su configuration file.

0028

How to enable the lynx browser to browse Chinese web pages (Ghost_Vale)

Modify the following settings when you browse the Simplified Chinese web page:

Save options to disk: [X]

Display and Character Set

Display character set: [Chinese ________________________]

Assumed document character set (!) : [Iso-8859-1 ______]

CJK mode (!) : [ON _]

Move to the bottom Accept Changes and press Enter to save it.

Of course, your system must support simplified Chinese.

0029

What should I do if the NIC is activated but cannot be connected to the network? (Slock)

Trace to see if the block is blocked.

1. Ping yourself

2. Ping the Gateway

3. Ping DNS

4. trace DNS

If All = OK

Then nslookup www.csai.cn

Ping csais address

Tra csai address

Basically, you can know the result.

0030

If samba is configured in redhat9, can win2000 access and win98 access? (Squall2003)

If it is wind98, you must modify the Registry: HKEY_LOCAL_MACHINE/system/ententcontrolset/services/Vxd/VNETSUP to create a D value: EnablePlainTextpasswd, key value 1

0031

How to obtain the MAC address of the NIC

Arp-a | awk {print $4}

0032

How to obtain the IP address of the NIC (mb)

Ifconfig eth0 | awk/inet addr/{split ($2, x, ":"); print x [2]}