Difference between revisions of "Networking"

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−
Check network connections
+
[[Category:networking]]
 +
[[Category:Linux/Unix]]
  
−
===Netcat===
+
=Check network connectivity=
−
;<code>nc <host> <port></code>
+
 
−
:Open connection to host on port. Works line tetnet
+
;netstat -nap
 +
:Show port status (LISTEN, ESTABLISHED, .....) and the program that owns it. You need to be root to see the process information
 +
 
 +
;<code>nc -v -z <host> <port></code>
 +
:Netcat: Tell me if we can open a connection to <host> on <port>. Without -z it works like telnet
 +
 
 +
;<code>nc -v -u -z <host> <port></code>
 +
:Tell me if we can open a connection to <host> on a UDP <port>
  
−
===Curl===
 
 
;<code>curl -vvv -k  --proxy1.0 <proxyIP>:<proxyPort> <Remote URL></code>
 
;<code>curl -vvv -k  --proxy1.0 <proxyIP>:<proxyPort> <Remote URL></code>
−
:Get the data from <remote URL> -k allows insecure SSL connections
+
:Get the data from <remote URL> via <proxyIP> -k allows insecure SSL connections
 +
 
 +
;<code>curl -vvv telnet://<IP>:<port></code>
 +
:Just test connectivity to a port
 +
 
 +
<syntaxhighlight lang=bash>
 +
#!/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
 +
</syntaxhighlight>
 +
 
 +
=[[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
 +
<syntaxhighlight lang=bash>
 +
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
 +
</syntaxhighlight>
 +
 
 +
;Disable an interface completely (even not shown by ifconfig)
 +
:vi /etc/modprobe.d/blackllst.conf
 +
:Put in the driver for your interface like: <code>blacklist ath9k</code>
 +
 
 +
=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=
 +
;<code>ssh -L 8080:remotehost:3006 proxy</code>
 +
: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 <code>-nNT</code> prevents that the ssh command opens a terminal on the proxy. The ssh command however must remain active.
 +
 
 +
=Tracing=
 +
For tracing traffic see [[Tcpdump]]
  
−
===Wget===
+
=Other=
 
;<code>wget <URL></code>
 
;<code>wget <URL></code>
 
:Get the data from <URL>
 
:Get the data from <URL>

Latest revision as of 16:26, 11 February 2024


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>
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