Showing posts with label Unix. Show all posts
Showing posts with label Unix. Show all posts
Download Ubuntu Theme for Windows Xp
Ubuntu is one of the popular operating systems while Windows is the largest used OS worldwide. If you are habituated with Ubuntu and recently started working on XP, you can do yourself a favor – install Ubuntu theme for XP so that you can get Ubuntu look and feel on Windows XP. This theme is designed by FioreSSJ at DeviantArt.
But before you read ahead, you need to patch uxtheme.dll file on your system so that non-Microsoft release visual style can be installed on Windows XP. If you have not applied this patch, download the patch from Softpedia and follow the instructions to install it on your system.
Now download Ubuntu theme for XP from here. This theme contains 5 different color schemes such as orange, blue, green, graphite and purple. Additionally it changes the Windows XP cursor and makes it look like xFree cursor. Once you have downloaded thetheme pack, extract the folder and follow the below steps :
- Copy files from Wallpaper folder to C:\Windows\Web\Wallpaper
- Copy files from Cursor folder to C:\Windows\Cursors
- Copy files from Fonts folder to C:\Windows\Fonts
- Copy other files to C:\Windows\Resources\Themes\Ubuntu (Make a new folder & rename it to Ubuntu yourself)
- Click Human to load the visual style
- Click Apply in display properties to save the changes
- You are done.
Ubuntu XP Theme
XP to Ubuntu transformation pack changes the visual style, desktop wallpaper, cursor, and fonts to give you Ubuntu feel and look on your Windows XP system. Now you can proceed to change system icons.
Download Tango Shell Patcher to make Windows XP icons look like Ubuntu 6.10 icons. Download the patch, read the instructions, install on your system and enjoy.
8:30 AM 0
List Of All Unix Commands For VPN (Virtual Private Network)
After posting a list of all unix comands for networking,this is ma second post related to unix..n its dealing with commnds for VPN(Virtual Private Networking)
As of version 4.3, OpenSSH can use the tun/tap device to encrypt a tunnel. This is very similar to other TLS based VPN solutions like OpenVPN. One advantage with SSH is that there is no need to install and configure additional software. Additionally the tunnel uses the SSH authentication like pre shared keys. The drawback is that the encapsulation is done over TCP which might result in poor performance on a slow link. Also the tunnel is relying on a single (fragile) TCP connection. This technique is very useful for a quick IP based VPN setup. There is no limitation as with the single TCP port forward, all layer 3/4 protocols like ICMP, TCP/UDP, etc. are forwarded over the VPN. In any case, the following options are needed in the sshd_conf file:
PermitRootLogin yes
PermitTunnel yes
Single P2P connection
Here we are connecting two hosts, hclient and hserver with a peer to peer tunnel. The connection is started from hclient to hserver and is done as root. The tunnel end points are 10.0.1.1 (server) and 10.0.1.2 (client) and we create a device tun5 (this could also be an other number). The procedure is very simple:
* Connect with SSH using the tunnel option -w
* Configure the IP addresses of the tunnel. Once on the server and once on the client.
Connect to the server
Connection started on the client and commands are executed on the server.
Server is on Linux
cli># ssh -w5:5 root@hserver
srv># ifconfig tun5 10.0.1.1 netmask 255.255.255.252 # Executed on the server shell
Server is on FreeBSD
cli># ssh -w5:5 root@hserver
srv># ifconfig tun5 10.0.1.1 10.0.1.2 # Executed on the server shell
Configure the client
Commands executed on the client:
cli># ifconfig tun5 10.0.1.2 netmask 255.255.255.252 # Client is on Linux
cli># ifconfig tun5 10.0.1.2 10.0.1.1 # Client is on FreeBSD
The two hosts are now connected and can transparently communicate with any layer 3/4 protocol using the tunnel IP addresses.
Connect two networks
In addition to the p2p setup above, it is more useful to connect two private networks with an SSH VPN using two gates. Suppose for the example, netA is 192.168.51.0/24 and netB 192.168.16.0/24. The procedure is similar as above, we only need to add the routing. NAT must be activated on the private interface only if the gates are not the same as the default gateway of their network.
192.168.51.0/24 (netA)|gateA <-> gateB|192.168.16.0/24 (netB)
* Connect with SSH using the tunnel option -w.
* Configure the IP addresses of the tunnel. Once on the server and once on the client.
* Add the routing for the two networks.
* If necessary, activate NAT on the private interface of the gate.
The setup is started from gateA in netA.
Connect from gateA to gateB
Connection is started from gateA and commands are executed on gateB.
gateB is on Linux
gateA># ssh -w5:5 root@gateB
gateB># ifconfig tun5 10.0.1.1 netmask 255.255.255.252 # Executed on the gateB shell
gateB># route add -net 192.168.51.0 netmask 255.255.255.0 dev tun5
gateB># echo 1 > /proc/sys/net/ipv4/ip_forward # Only needed if not default gw
gateB># iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
gateB is on FreeBSD
gateA># ssh -w5:5 root@gateB # Creates the tun5 devices
gateB># ifconfig tun5 10.0.1.1 10.0.1.2 # Executed on the gateB shell
gateB># route add 192.168.51.0/24 10.0.1.2
gateB># sysctl net.inet.ip.forwarding=1 # Only needed if not default gw
gateB># natd -s -m -u -dynamic -n fxp0 # see NAT
gateA># sysctl net.inet.ip.fw.enable=1
Configure gateA
Commands executed on gateA:
gateA is on Linux
gateA># ifconfig tun5 10.0.1.2 netmask 255.255.255.252
gateA># route add -net 192.168.16.0 netmask 255.255.255.0 dev tun5
gateA># echo 1 > /proc/sys/net/ipv4/ip_forward
gateA># iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
gateA is on FreeBSD
gateA># ifconfig tun5 10.0.1.2 10.0.1.1
gateA># route add 192.168.16.0/24 10.0.1.2
gateA># sysctl net.inet.ip.forwarding=1
gateA># natd -s -m -u -dynamic -n fxp0 # see NAT
gateA># sysctl net.inet.ip.fw.enable=1
The two private networks are now transparently connected via the SSH VPN. The IP forward and NAT settings are only necessary if the gates are not the default gateways. In this case the clients would not know where to forward the response, and nat must be activated.
As of version 4.3, OpenSSH can use the tun/tap device to encrypt a tunnel. This is very similar to other TLS based VPN solutions like OpenVPN. One advantage with SSH is that there is no need to install and configure additional software. Additionally the tunnel uses the SSH authentication like pre shared keys. The drawback is that the encapsulation is done over TCP which might result in poor performance on a slow link. Also the tunnel is relying on a single (fragile) TCP connection. This technique is very useful for a quick IP based VPN setup. There is no limitation as with the single TCP port forward, all layer 3/4 protocols like ICMP, TCP/UDP, etc. are forwarded over the VPN. In any case, the following options are needed in the sshd_conf file:
PermitRootLogin yes
PermitTunnel yes
Single P2P connection
Here we are connecting two hosts, hclient and hserver with a peer to peer tunnel. The connection is started from hclient to hserver and is done as root. The tunnel end points are 10.0.1.1 (server) and 10.0.1.2 (client) and we create a device tun5 (this could also be an other number). The procedure is very simple:
* Connect with SSH using the tunnel option -w
* Configure the IP addresses of the tunnel. Once on the server and once on the client.
Connect to the server
Connection started on the client and commands are executed on the server.
Server is on Linux
cli># ssh -w5:5 root@hserver
srv># ifconfig tun5 10.0.1.1 netmask 255.255.255.252 # Executed on the server shell
Server is on FreeBSD
cli># ssh -w5:5 root@hserver
srv># ifconfig tun5 10.0.1.1 10.0.1.2 # Executed on the server shell
Configure the client
Commands executed on the client:
cli># ifconfig tun5 10.0.1.2 netmask 255.255.255.252 # Client is on Linux
cli># ifconfig tun5 10.0.1.2 10.0.1.1 # Client is on FreeBSD
The two hosts are now connected and can transparently communicate with any layer 3/4 protocol using the tunnel IP addresses.
Connect two networks
In addition to the p2p setup above, it is more useful to connect two private networks with an SSH VPN using two gates. Suppose for the example, netA is 192.168.51.0/24 and netB 192.168.16.0/24. The procedure is similar as above, we only need to add the routing. NAT must be activated on the private interface only if the gates are not the same as the default gateway of their network.
192.168.51.0/24 (netA)|gateA <-> gateB|192.168.16.0/24 (netB)
* Connect with SSH using the tunnel option -w.
* Configure the IP addresses of the tunnel. Once on the server and once on the client.
* Add the routing for the two networks.
* If necessary, activate NAT on the private interface of the gate.
The setup is started from gateA in netA.
Connect from gateA to gateB
Connection is started from gateA and commands are executed on gateB.
gateB is on Linux
gateA># ssh -w5:5 root@gateB
gateB># ifconfig tun5 10.0.1.1 netmask 255.255.255.252 # Executed on the gateB shell
gateB># route add -net 192.168.51.0 netmask 255.255.255.0 dev tun5
gateB># echo 1 > /proc/sys/net/ipv4/ip_forward # Only needed if not default gw
gateB># iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
gateB is on FreeBSD
gateA># ssh -w5:5 root@gateB # Creates the tun5 devices
gateB># ifconfig tun5 10.0.1.1 10.0.1.2 # Executed on the gateB shell
gateB># route add 192.168.51.0/24 10.0.1.2
gateB># sysctl net.inet.ip.forwarding=1 # Only needed if not default gw
gateB># natd -s -m -u -dynamic -n fxp0 # see NAT
gateA># sysctl net.inet.ip.fw.enable=1
Configure gateA
Commands executed on gateA:
gateA is on Linux
gateA># ifconfig tun5 10.0.1.2 netmask 255.255.255.252
gateA># route add -net 192.168.16.0 netmask 255.255.255.0 dev tun5
gateA># echo 1 > /proc/sys/net/ipv4/ip_forward
gateA># iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
gateA is on FreeBSD
gateA># ifconfig tun5 10.0.1.2 10.0.1.1
gateA># route add 192.168.16.0/24 10.0.1.2
gateA># sysctl net.inet.ip.forwarding=1
gateA># natd -s -m -u -dynamic -n fxp0 # see NAT
gateA># sysctl net.inet.ip.fw.enable=1
The two private networks are now transparently connected via the SSH VPN. The IP forward and NAT settings are only necessary if the gates are not the default gateways. In this case the clients would not know where to forward the response, and nat must be activated.
9:42 PM 0
List Of all UNIX Networking Commands
Here is the list of all unix commands that i had been familiar with onceor more..
Js go thru them n if u finds any command missing, pls do contribute over comments...
Thanx in advance.
Hehehe!!
Here v GO...
Debugging
# mii-diag eth0 # Show the link status (Linux)
# ifconfig fxp0 # Check the “media” field on FreeBSD
# arp -a # Check the router (or host) ARP entry (all OS)
# ping cb.vu # The first thing to try…
# traceroute cb.vu # Print the route path to destination
# mii-diag -F 100baseTx-FD eth0 # Force 100Mbit Full duplex (Linux)
# ifconfig fxp0 media 100baseTX mediaopt full-duplex # Same for FreeBSD
# netstat -s # System-wide statistics for each network protocol
Routing
Print routing table
# route -n # Linux
# netstat -rn # Linux, BSD and UNIX
# route print # Windows
Add and delete a route
FreeBSD
# route add 212.117.0.0/16 192.168.1.1
# route delete 212.117.0.0/16
# route add default 192.168.1.1
Add the route permanently in /etc/rc.conf
static_routes="myroute"
route_myroute="-net 212.117.0.0/16 192.168.1.1"
Linux
# route add -net 192.168.20.0 netmask 255.255.255.0 gw 192.168.16.254
# ip route add 192.168.20.0/24 via 192.168.16.254 # same as above with ip route
# route add -net 192.168.20.0 netmask 255.255.255.0 dev eth0
# route add default gw 192.168.51.254
# ip route add default via 192.168.51.254 # same as above with ip route
# route delete -net 192.168.20.0 netmask 255.255.255.0
Windows
# Route add 192.168.50.0 mask 255.255.255.0 192.168.51.253
# Route add 0.0.0.0 mask 0.0.0.0 192.168.51.254
Use add -p to make the route persistent.
Configure additional IP addresses
Linux
# ifconfig eth0 192.168.50.254 netmask 255.255.255.0 # First IP
# ifconfig eth0:0 192.168.51.254 netmask 255.255.255.0 # Second IP
FreeBSD
# ifconfig fxp0 inet 192.168.50.254/24 # First IP
# ifconfig fxp0 alias 192.168.51.254 netmask 255.255.255.0 # Second IP
Permanent entries in /etc/rc.conf
ifconfig_fxp0="inet 192.168.50.254 netmask 255.255.255.0"
ifconfig_fxp0_alias0="192.168.51.254 netmask 255.255.255.0"
Change MAC address
# ifconfig eth0 hw ether 00:01:02:03:04:05 # Linux
# ifconfig fxp0 link 00:01:02:03:04:05 # FreeBSD
Ports in use
Listening open ports:
# netstat -an | grep LISTEN
# lsof -i # Linux list all Internet connections
# socklist # Linux display list of open sockets
# sockstat -4 # FreeBSD application listing
# netstat -anp –udp –tcp | grep LISTEN # Linux
# netstat -tup # List active connections to/from system (Linux)
# netstat -tupl # List listening ports from system (Linux)
# netstat -ano # Windows
Firewall
Check if a firewall is running (typical configuration only):
Linux
# iptables -L -n -v # For status
Open the iptables firewall
# iptables -Z # Zero the packet and byte counters in all chains
# iptables -F # Flush all chains
# iptables -X # Delete all chains
# iptables -P INPUT ACCEPT # Open everything
# iptables -P FORWARD ACCEPT
# iptables -P OUTPUT ACCEPT
FreeBSD
# ipfw show # For status
# ipfw list 65535 # if answer is “65535 deny ip from any to any” the fw is disabled
# sysctl net.inet.ip.fw.enable=0 # Disable
# sysctl net.inet.ip.fw.enable=1 # Enable
IP Forward for routing
Linux
Check and then enable IP forward with:
# cat /proc/sys/net/ipv4/ip_forward # Check IP forward 0=off, 1=on
# echo 1 > /proc/sys/net/ipv4/ip_forward
or edit /etc/sysctl.conf with:
net.ipv4.ip_forward = 1
FreeBSD
Check and enable with:
# sysctl net.inet.ip.forwarding # Check IP forward 0=off, 1=on
# sysctl net.inet.ip.forwarding=1
# sysctl net.inet.ip.fastforwarding=1 # For dedicated router or firewall
Permanent with entry in /etc/rc.conf:
gateway_enable=”YES” # Set to YES if this host will be a gateway.
NAT Network Address Translation
Linux
# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # to activate NAT
# iptables -t nat -A PREROUTING -p tcp -d 78.31.70.238 –dport 20022 -j DNAT
–to 192.168.16.44:22 # Port forward 20022 to internal IP port ssh
# iptables -t nat -A PREROUTING -p tcp -d 78.31.70.238 –dport 993:995 -j DNAT
–to 192.168.16.254:993:995 # Port forward of range 993-995
# ip route flush cache
# iptables -L -t nat # Check NAT status
Delete the port forward with -D instead of -A.
FreeBSD
# natd -s -m -u -dynamic -f /etc/natd.conf -n fxp0
Or edit /etc/rc.conf with:
firewall_enable="YES" # Set to YES to enable firewall functionality
firewall_type=”open” # Firewall type (see /etc/rc.firewall)
natd_enable=”YES” # Enable natd (if firewall_enable == YES).
natd_interface=”tun0″ # Public interface or IP address to use.
natd_flags=”-s -m -u -dynamic -f /etc/natd.conf”
Port forward with:
# cat /etc/natd.conf
same_ports yes
use_sockets yes
unregistered_only
# redirect_port tcp insideIP:2300-2399 3300-3399 # port range
redirect_port udp 192.168.51.103:7777 7777
DNS
On Unix the DNS entries are valid for all interfaces and are stored in /etc/resolv.conf. The domain to which the host belongs is also stored in this file. A minimal configuration is:
nameserver 78.31.70.238
search sleepyowl.net intern.lab
domain sleepyowl.net
Check the system domain name with:
# hostname -d # Same as dnsdomainname
Windows
On Windows the DNS are configured per interface. To display the configured DNS and to flush the DNS cache use:
# ipconfig /? # Display help
# ipconfig /all # See all information including DNS
# ipconfig /flushdns # Flush the DNS cache
Forward queries
Dig is you friend to test the DNS settings. For example the public DNS server 213.133.105.2 ns.second-ns.de can be used for testing. See from which server the client receives the answer (simplified answer).
# dig sleepyowl.net
sleepyowl.net. 600 IN A 78.31.70.238
;; SERVER: 192.168.51.254#53(192.168.51.254)
The router 192.168.51.254 answered and the response is the A entry. Any entry can be queried and the DNS server can be selected with @:
# dig MX google.com
# dig @127.0.0.1 NS sun.com # To test the local server
# dig @204.97.212.10 NS MX heise.de # Query an external server
# dig AXFR @ns1.xname.org cb.vu # Get the full zone (zone transfer)
The program host is also powerful.
# host -t MX cb.vu # Get the mail MX entry
# host -t NS -T sun.com # Get the NS record over a TCP connection
# host -a sleepyowl.net # Get everything
Reverse queries
Find the name belonging to an IP address (in-addr.arpa.). This can be done with dig, host and nslookup:
# dig -x 78.31.70.238
# host 78.31.70.238
# nslookup 78.31.70.238
/etc/hosts
Single hosts can be configured in the file /etc/hosts instead of running named locally to resolve the hostname queries. The format is simple, for example:
78.31.70.238 sleepyowl.net sleepyowl
The priority between hosts and a dns query, that is the name resolution order, can be configured in /etc/nsswitch.conf AND /etc/host.conf. The file also exists on Windows, it is usually in:
C:WINDOWSSYSTEM32DRIVERSETC
DHCP
Linux
Some distributions (SuSE) use dhcpcd as client. The default interface is eth0.
# dhcpcd -n eth0 # Trigger a renew
# dhcpcd -k eth0 # release and shutdown
The lease with the full information is stored in:
/var/lib/dhcpcd/dhcpcd-eth0.info
FreeBSD
FreeBSD (and Debian) uses dhclient. To configure an interface (for example bge0) run:
# dhclient bge0
The lease with the full information is stored in:
/var/db/dhclient.leases.bge0
Use
/etc/dhclient.conf
to prepend options or force different options:
# cat /etc/dhclient.conf
interface "rl0" {
prepend domain-name-servers 127.0.0.1;
default domain-name "sleepyowl.net";
supersede domain-name "sleepyowl.net";
}
Windows
The dhcp lease can be renewed with ipconfig:
# ipconfig /renew # renew all adapters
# ipconfig /renew LAN # renew the adapter named “LAN”
# ipconfig /release WLAN # release the adapter named “WLAN”
Yes it is a good idea to rename you adapter with simple names!
Traffic analysis
Bmon http://people.suug.ch/~tgr/bmon/ is a small console bandwidth monitor and can display the flow on different interfaces.
Sniff with tcpdump
# tcpdump -nl -i bge0 not port ssh and src (192.168.16.121 or 192.168.16.54)
# tcpdump -l > dump && tail -f dump # Buffered output
# tcpdump -i rl0 -w traffic.rl0 # Write traffic in binary file
# tcpdump -r traffic.rl0 # Read from file (also for ethereal
# tcpdump port 80 # The two classic commands
# tcpdump host google.com
# tcpdump -i eth0 -X port (110 or 143) # Check if pop or imap is secure
# tcpdump -n -i eth0 icmp # Only catch pings
# tcpdump -i eth0 -s 0 -A port 80 | grep GET # -s 0 for full packet -A for ASCII
Additional important options:
* -A Print each packets in clear text (without header)
* -X Print packets in hex and ASCII
* -l Make stdout line buffered
* -D Print all interfaces available
On Windows use windump from http://www.winpcap.org/. Use windump -D to list the interfaces.
Scan with nmap
Nmap http://insecure.org/nmap/ is a port scanner with OS detection, it is usually installed on most distributions and is also available for Windows. If you don’t scan your servers, hackers do it for you…
# nmap cb.vu # scans all reserved TCP ports on the host
# nmap -sP 192.168.16.0/24 # Find out which IP are used and by which host on 0/24
# nmap -sS -sV -O cb.vu # Do a stealth SYN scan with version and OS detection
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 3.8.1p1 FreeBSD-20060930 (protocol 2.0)
25/tcp open smtp Sendmail smtpd 8.13.6/8.13.6
80/tcp open http Apache httpd 2.0.59 ((FreeBSD) DAV/2 PHP/4.
[…]
Running: FreeBSD 5.X
Uptime 33.120 days (since Fri Aug 31 11:41:04 2007)
Traffic control (QoS)
Traffic control manages the queuing, policing, scheduling, and other traffic parameters for a network. The following examples are simple practical uses of the Linux and FreeBSD capabilities to better use the available bandwidth.
Limit upload
DSL or cable modems have a long queue to improve the upload throughput. However filling the queue with a fast device (e.g. ethernet) will dramatically decrease the interactivity. It is therefore useful to limit the device upload rate to match the physical capacity of the modem, this should greatly improve the interactivity. Set to about 90% of the modem maximal (cable) speed.
Linux
For a 512 Kbit upload modem.
# tc qdisc add dev eth0 root tbf rate 480kbit latency 50ms burst 1540
# tc -s qdisc ls dev eth0 # Status
# tc qdisc del dev eth0 root # Delete the queue
# tc qdisc change dev eth0 root tbf rate 220kbit latency 50ms burst 1540
FreeBSD
FreeBSD uses the dummynet traffic shaper which is configured with ipfw. Pipes are used to set limits the bandwidth in units of [K|M]{bit/s|Byte/s}, 0 means unlimited bandwidth. Using the same pipe number will reconfigure it. For example limit the upload bandwidth to 500 Kbit.
# kldload dummynet # load the module if necessary
# ipfw pipe 1 config bw 500Kbit/s # create a pipe with limited bandwidth
# ipfw add pipe 1 ip from me to any # divert the full upload into the pipe
Quality of service
Linux
Priority queuing with tc to optimize VoIP. See the full example on voip-info.org or http://www.howtoforge.com/voip_qos_traffic_shaping_iproute2_asterisk. Suppose VoIP uses udp on ports 10000:11024 and device eth0 (could also be ppp0 or so). The following commands define the QoS to three queues and force the VoIP traffic to queue 1 with QoS 0×1e (all bits set). The default traffic flows into queue 3 and QoS Minimize-Delay flows into queue 2.
# tc qdisc add dev eth0 root handle 1: prio priomap 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 0
# tc qdisc add dev eth0 parent 1:1 handle 10: sfq
# tc qdisc add dev eth0 parent 1:2 handle 20: sfq
# tc qdisc add dev eth0 parent 1:3 handle 30: sfq
# tc filter add dev eth0 protocol ip parent 1: prio 1 u32
match ip dport 10000 0x3C00 flowid 1:1 # use server port range
match ip dst 123.23.0.1 flowid 1:1 # or/and use server IP
Status and remove with
# tc -s qdisc ls dev eth0 # queue status
# tc qdisc del dev eth0 root # delete all QoS
Calculate port range and mask
The tc filter defines the port range with port and mask which you have to calculate. Find the 2^N ending of the port range, deduce the range and convert to HEX. This is your mask. Example for 10000 -> 11024, the range is 1024.
# 2^13 (8192) < 14 =" 16384" obase="16;(2^14)-1024″">
Js go thru them n if u finds any command missing, pls do contribute over comments...
Thanx in advance.
Hehehe!!
Here v GO...
Debugging
# mii-diag eth0 # Show the link status (Linux)
# ifconfig fxp0 # Check the “media” field on FreeBSD
# arp -a # Check the router (or host) ARP entry (all OS)
# ping cb.vu # The first thing to try…
# traceroute cb.vu # Print the route path to destination
# mii-diag -F 100baseTx-FD eth0 # Force 100Mbit Full duplex (Linux)
# ifconfig fxp0 media 100baseTX mediaopt full-duplex # Same for FreeBSD
# netstat -s # System-wide statistics for each network protocol
Routing
Print routing table
# route -n # Linux
# netstat -rn # Linux, BSD and UNIX
# route print # Windows
Add and delete a route
FreeBSD
# route add 212.117.0.0/16 192.168.1.1
# route delete 212.117.0.0/16
# route add default 192.168.1.1
Add the route permanently in /etc/rc.conf
static_routes="myroute"
route_myroute="-net 212.117.0.0/16 192.168.1.1"
Linux
# route add -net 192.168.20.0 netmask 255.255.255.0 gw 192.168.16.254
# ip route add 192.168.20.0/24 via 192.168.16.254 # same as above with ip route
# route add -net 192.168.20.0 netmask 255.255.255.0 dev eth0
# route add default gw 192.168.51.254
# ip route add default via 192.168.51.254 # same as above with ip route
# route delete -net 192.168.20.0 netmask 255.255.255.0
Windows
# Route add 192.168.50.0 mask 255.255.255.0 192.168.51.253
# Route add 0.0.0.0 mask 0.0.0.0 192.168.51.254
Use add -p to make the route persistent.
Configure additional IP addresses
Linux
# ifconfig eth0 192.168.50.254 netmask 255.255.255.0 # First IP
# ifconfig eth0:0 192.168.51.254 netmask 255.255.255.0 # Second IP
FreeBSD
# ifconfig fxp0 inet 192.168.50.254/24 # First IP
# ifconfig fxp0 alias 192.168.51.254 netmask 255.255.255.0 # Second IP
Permanent entries in /etc/rc.conf
ifconfig_fxp0="inet 192.168.50.254 netmask 255.255.255.0"
ifconfig_fxp0_alias0="192.168.51.254 netmask 255.255.255.0"
Change MAC address
# ifconfig eth0 hw ether 00:01:02:03:04:05 # Linux
# ifconfig fxp0 link 00:01:02:03:04:05 # FreeBSD
Ports in use
Listening open ports:
# netstat -an | grep LISTEN
# lsof -i # Linux list all Internet connections
# socklist # Linux display list of open sockets
# sockstat -4 # FreeBSD application listing
# netstat -anp –udp –tcp | grep LISTEN # Linux
# netstat -tup # List active connections to/from system (Linux)
# netstat -tupl # List listening ports from system (Linux)
# netstat -ano # Windows
Firewall
Check if a firewall is running (typical configuration only):
Linux
# iptables -L -n -v # For status
Open the iptables firewall
# iptables -Z # Zero the packet and byte counters in all chains
# iptables -F # Flush all chains
# iptables -X # Delete all chains
# iptables -P INPUT ACCEPT # Open everything
# iptables -P FORWARD ACCEPT
# iptables -P OUTPUT ACCEPT
FreeBSD
# ipfw show # For status
# ipfw list 65535 # if answer is “65535 deny ip from any to any” the fw is disabled
# sysctl net.inet.ip.fw.enable=0 # Disable
# sysctl net.inet.ip.fw.enable=1 # Enable
IP Forward for routing
Linux
Check and then enable IP forward with:
# cat /proc/sys/net/ipv4/ip_forward # Check IP forward 0=off, 1=on
# echo 1 > /proc/sys/net/ipv4/ip_forward
or edit /etc/sysctl.conf with:
net.ipv4.ip_forward = 1
FreeBSD
Check and enable with:
# sysctl net.inet.ip.forwarding # Check IP forward 0=off, 1=on
# sysctl net.inet.ip.forwarding=1
# sysctl net.inet.ip.fastforwarding=1 # For dedicated router or firewall
Permanent with entry in /etc/rc.conf:
gateway_enable=”YES” # Set to YES if this host will be a gateway.
NAT Network Address Translation
Linux
# iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE # to activate NAT
# iptables -t nat -A PREROUTING -p tcp -d 78.31.70.238 –dport 20022 -j DNAT
–to 192.168.16.44:22 # Port forward 20022 to internal IP port ssh
# iptables -t nat -A PREROUTING -p tcp -d 78.31.70.238 –dport 993:995 -j DNAT
–to 192.168.16.254:993:995 # Port forward of range 993-995
# ip route flush cache
# iptables -L -t nat # Check NAT status
Delete the port forward with -D instead of -A.
FreeBSD
# natd -s -m -u -dynamic -f /etc/natd.conf -n fxp0
Or edit /etc/rc.conf with:
firewall_enable="YES" # Set to YES to enable firewall functionality
firewall_type=”open” # Firewall type (see /etc/rc.firewall)
natd_enable=”YES” # Enable natd (if firewall_enable == YES).
natd_interface=”tun0″ # Public interface or IP address to use.
natd_flags=”-s -m -u -dynamic -f /etc/natd.conf”
Port forward with:
# cat /etc/natd.conf
same_ports yes
use_sockets yes
unregistered_only
# redirect_port tcp insideIP:2300-2399 3300-3399 # port range
redirect_port udp 192.168.51.103:7777 7777
DNS
On Unix the DNS entries are valid for all interfaces and are stored in /etc/resolv.conf. The domain to which the host belongs is also stored in this file. A minimal configuration is:
nameserver 78.31.70.238
search sleepyowl.net intern.lab
domain sleepyowl.net
Check the system domain name with:
# hostname -d # Same as dnsdomainname
Windows
On Windows the DNS are configured per interface. To display the configured DNS and to flush the DNS cache use:
# ipconfig /? # Display help
# ipconfig /all # See all information including DNS
# ipconfig /flushdns # Flush the DNS cache
Forward queries
Dig is you friend to test the DNS settings. For example the public DNS server 213.133.105.2 ns.second-ns.de can be used for testing. See from which server the client receives the answer (simplified answer).
# dig sleepyowl.net
sleepyowl.net. 600 IN A 78.31.70.238
;; SERVER: 192.168.51.254#53(192.168.51.254)
The router 192.168.51.254 answered and the response is the A entry. Any entry can be queried and the DNS server can be selected with @:
# dig MX google.com
# dig @127.0.0.1 NS sun.com # To test the local server
# dig @204.97.212.10 NS MX heise.de # Query an external server
# dig AXFR @ns1.xname.org cb.vu # Get the full zone (zone transfer)
The program host is also powerful.
# host -t MX cb.vu # Get the mail MX entry
# host -t NS -T sun.com # Get the NS record over a TCP connection
# host -a sleepyowl.net # Get everything
Reverse queries
Find the name belonging to an IP address (in-addr.arpa.). This can be done with dig, host and nslookup:
# dig -x 78.31.70.238
# host 78.31.70.238
# nslookup 78.31.70.238
/etc/hosts
Single hosts can be configured in the file /etc/hosts instead of running named locally to resolve the hostname queries. The format is simple, for example:
78.31.70.238 sleepyowl.net sleepyowl
The priority between hosts and a dns query, that is the name resolution order, can be configured in /etc/nsswitch.conf AND /etc/host.conf. The file also exists on Windows, it is usually in:
C:WINDOWSSYSTEM32DRIVERSETC
DHCP
Linux
Some distributions (SuSE) use dhcpcd as client. The default interface is eth0.
# dhcpcd -n eth0 # Trigger a renew
# dhcpcd -k eth0 # release and shutdown
The lease with the full information is stored in:
/var/lib/dhcpcd/dhcpcd-eth0.info
FreeBSD
FreeBSD (and Debian) uses dhclient. To configure an interface (for example bge0) run:
# dhclient bge0
The lease with the full information is stored in:
/var/db/dhclient.leases.bge0
Use
/etc/dhclient.conf
to prepend options or force different options:
# cat /etc/dhclient.conf
interface "rl0" {
prepend domain-name-servers 127.0.0.1;
default domain-name "sleepyowl.net";
supersede domain-name "sleepyowl.net";
}
Windows
The dhcp lease can be renewed with ipconfig:
# ipconfig /renew # renew all adapters
# ipconfig /renew LAN # renew the adapter named “LAN”
# ipconfig /release WLAN # release the adapter named “WLAN”
Yes it is a good idea to rename you adapter with simple names!
Traffic analysis
Bmon http://people.suug.ch/~tgr/bmon/ is a small console bandwidth monitor and can display the flow on different interfaces.
Sniff with tcpdump
# tcpdump -nl -i bge0 not port ssh and src (192.168.16.121 or 192.168.16.54)
# tcpdump -l > dump && tail -f dump # Buffered output
# tcpdump -i rl0 -w traffic.rl0 # Write traffic in binary file
# tcpdump -r traffic.rl0 # Read from file (also for ethereal
# tcpdump port 80 # The two classic commands
# tcpdump host google.com
# tcpdump -i eth0 -X port (110 or 143) # Check if pop or imap is secure
# tcpdump -n -i eth0 icmp # Only catch pings
# tcpdump -i eth0 -s 0 -A port 80 | grep GET # -s 0 for full packet -A for ASCII
Additional important options:
* -A Print each packets in clear text (without header)
* -X Print packets in hex and ASCII
* -l Make stdout line buffered
* -D Print all interfaces available
On Windows use windump from http://www.winpcap.org/. Use windump -D to list the interfaces.
Scan with nmap
Nmap http://insecure.org/nmap/ is a port scanner with OS detection, it is usually installed on most distributions and is also available for Windows. If you don’t scan your servers, hackers do it for you…
# nmap cb.vu # scans all reserved TCP ports on the host
# nmap -sP 192.168.16.0/24 # Find out which IP are used and by which host on 0/24
# nmap -sS -sV -O cb.vu # Do a stealth SYN scan with version and OS detection
PORT STATE SERVICE VERSION
22/tcp open ssh OpenSSH 3.8.1p1 FreeBSD-20060930 (protocol 2.0)
25/tcp open smtp Sendmail smtpd 8.13.6/8.13.6
80/tcp open http Apache httpd 2.0.59 ((FreeBSD) DAV/2 PHP/4.
[…]
Running: FreeBSD 5.X
Uptime 33.120 days (since Fri Aug 31 11:41:04 2007)
Traffic control (QoS)
Traffic control manages the queuing, policing, scheduling, and other traffic parameters for a network. The following examples are simple practical uses of the Linux and FreeBSD capabilities to better use the available bandwidth.
Limit upload
DSL or cable modems have a long queue to improve the upload throughput. However filling the queue with a fast device (e.g. ethernet) will dramatically decrease the interactivity. It is therefore useful to limit the device upload rate to match the physical capacity of the modem, this should greatly improve the interactivity. Set to about 90% of the modem maximal (cable) speed.
Linux
For a 512 Kbit upload modem.
# tc qdisc add dev eth0 root tbf rate 480kbit latency 50ms burst 1540
# tc -s qdisc ls dev eth0 # Status
# tc qdisc del dev eth0 root # Delete the queue
# tc qdisc change dev eth0 root tbf rate 220kbit latency 50ms burst 1540
FreeBSD
FreeBSD uses the dummynet traffic shaper which is configured with ipfw. Pipes are used to set limits the bandwidth in units of [K|M]{bit/s|Byte/s}, 0 means unlimited bandwidth. Using the same pipe number will reconfigure it. For example limit the upload bandwidth to 500 Kbit.
# kldload dummynet # load the module if necessary
# ipfw pipe 1 config bw 500Kbit/s # create a pipe with limited bandwidth
# ipfw add pipe 1 ip from me to any # divert the full upload into the pipe
Quality of service
Linux
Priority queuing with tc to optimize VoIP. See the full example on voip-info.org or http://www.howtoforge.com/voip_qos_traffic_shaping_iproute2_asterisk. Suppose VoIP uses udp on ports 10000:11024 and device eth0 (could also be ppp0 or so). The following commands define the QoS to three queues and force the VoIP traffic to queue 1 with QoS 0×1e (all bits set). The default traffic flows into queue 3 and QoS Minimize-Delay flows into queue 2.
# tc qdisc add dev eth0 root handle 1: prio priomap 2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 0
# tc qdisc add dev eth0 parent 1:1 handle 10: sfq
# tc qdisc add dev eth0 parent 1:2 handle 20: sfq
# tc qdisc add dev eth0 parent 1:3 handle 30: sfq
# tc filter add dev eth0 protocol ip parent 1: prio 1 u32
match ip dport 10000 0x3C00 flowid 1:1 # use server port range
match ip dst 123.23.0.1 flowid 1:1 # or/and use server IP
Status and remove with
# tc -s qdisc ls dev eth0 # queue status
# tc qdisc del dev eth0 root # delete all QoS
Calculate port range and mask
The tc filter defines the port range with port and mask which you have to calculate. Find the 2^N ending of the port range, deduce the range and convert to HEX. This is your mask. Example for 10000 -> 11024, the range is 1024.
# 2^13 (8192) < 14 =" 16384" obase="16;(2^14)-1024″">
9:30 PM 0
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