Networking
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Check network connectivity
- netstat -nap
- Show port status (LISTEN, ESTABLISHED, .....) and the program that owns it. You need to be root to see the process information
nc -v -z <host> <port>
- Netcat: Tell me if we can open a connection to <host> on <port>. Without -z it works like telnet
nc -v -u -z <host> <port>
- Tell me if we can open a connection to <host> on a UDP <port>
curl -vvv -k --proxy1.0 <proxyIP>:<proxyPort> <Remote URL>
- Get the data from <remote URL> via <proxyIP> -k allows insecure SSL connections
curl -vvv telnet://<IP>:<port>
- Just test connectivity to a port
#!/bin/bash
PORT=$1
TARGETS="999.999.999.999
888.888.888.888
777.777.777.777
666.666.666.666
"
for TARGET in ${TARGETS}
do
curl http://${TARGET}:${PORT} --connect-timeout 1 > /dev/null 2>&1
if [ $? == 28 ] # 28 is the curl code for connection timeout
then
echo No connection to ${TARGET}:${PORT}
fi
done
OpenSSL
See the OpenSSL page
Interfaces
- ifconfig -a
- Show all network interfaces
- ifconfig <interface> <ipaddress>
- Assign <ipaddress> to <interface>
- ip -a address
- ip -a -6 address
- Show all IP adresses
- Show all IPv4 addresses
- ip -6 addr add <ipv6address>/<prefixlength> dev <interface>
- Add an IPv6 address to <interface>
- mii-tool <interface>
- Show interface link status (speed)
- The interfaces file
apt-get purge network-manager
vi /etc/network/interfaces
auto <interface> # Boot process waits until the interface is up or a time-out (5 minutes)
allow-hotplug <interface> # Boot process does not wait for the interface.
iface <interface> inet dhcp
wpa-ssid <ssid>
wpa-psk <password>
# To have ipv6 autoconfigured (by radvd) and add own address
iface <interface> inet6 static
address unique:local:address:prefix:your:own:host:address
autoconf 1
netmask 64
# Add another address to <interface>(work for IPv4 addresses too
iface <interface> inet6 static
address unique:local:address:prefix:your:own:host:address
netmask 64
# To have ipv6 autoconfigured (by radvd) and query a dhcp-server
iface <interface> inet6 dhcp
autoconf 1
- Disable an interface completely (even not shown by ifconfig)
- vi /etc/modprobe.d/blackllst.conf
- Put in the driver for your interface like:
blacklist ath9k
Wireless
- iwscan <interface> scanning
- Show available accesspoints
- iwconfig <interface>
- Show details of the wireless connection
Routing
- route add -net default gw <IPaddress>
- Add a default route using <IPaddress> as gateway
Tunneling
ssh -L 8080:remotehost:3006 proxy
- Login over ssh to proxy and there connect to remotehost port 3006. Connect local port 8080 to the remote connection.
- Now if you connect to port 8080 on your local server you are connected to port 3006 on the remotehost
- Using
-nNT
prevents that the ssh command opens a terminal on the proxy. The ssh command however must remain active.
Tracing
For tracing traffic see Tcpdump
Other
wget <URL>
- Get the data from <URL>