Difference between revisions of "Networking"

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[[Category:networking]]
 
[[Category:networking]]
 
[[Category:Linux/Unix]]
 
[[Category:Linux/Unix]]
−
==Check network connections==
 
  
−
===Netcat===
+
==Check network connectivity==
 +
 
 +
;netstat -nap
 +
:Show port status (LISTEN, ESTABLISHED, .....) and the program that owns it.
 +
 
 
;<code>nc -v -z <host> <port></code>
 
;<code>nc -v -z <host> <port></code>
−
:Tell me if we can open a connection to <host> on <port>. Without -z it works like telnet
+
: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>
 
;<code>nc -v -u -z <host> <port></code>
 
:Tell me if we can open a connection to <host> on a UDP <port>
 
: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> via <proxyIP> -k allows insecure SSL connections
 
:Get the data from <remote URL> via <proxyIP> -k allows insecure SSL connections
Line 17: Line 19:
 
:Just test connectivity to a port
 
:Just test connectivity to a port
  
−
===Wget===
+
<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 ]
 +
  then
 +
    echo No connection to ${TARGET}:${PORT}
 +
  fi
 +
done
 +
</syntaxhighlight>
 +
 
 
;<code>wget <URL></code>
 
;<code>wget <URL></code>
 
:Get the data from <URL>
 
:Get the data from <URL>
  
 
===[[OpenSSL]]===
 
===[[OpenSSL]]===
 +
See the [[OpenSSL]] page
  
 
==Interfaces==
 
==Interfaces==
Line 29: Line 52:
 
;ifconfig <interface> <ipaddrss>
 
;ifconfig <interface> <ipaddrss>
 
:Assign <ipaddress> to <interface>
 
:Assign <ipaddress> to <interface>
 +
 +
;ip -6 addr add <ipv6address>/<prefixlength> dev <interface>
 +
:Add an IPv6 address to <interface>
  
 
;mii-tool <interface>
 
;mii-tool <interface>
 
:Show interface link status (speed)
 
:Show interface link status (speed)
 +
 +
;The interfaces file
 +
<syntaxhighlight lang=bash>
 +
apt-get purge network-manager
 +
vi /etc/network/interfaces
 +
auto <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>
 +
 +
For interfaces that may not be connected use <code>allow-hotplug</code> instead of <code>auto</code>.<br>
 +
The bootprocces now does not wait for an DCHP-answer on disconnected interfaces. Saves you about 5 minutes during startup.
 +
 +
==Routing==
 +
;route add -net default gw <IPaddress>
 +
:Add a default route using <IPaddress>  as gateway
  
 
==Tunneling==
 
==Tunneling==
Line 38: Line 96:
 
:Now if you connect to port 8080 on your local server you are connected to port 3006 on the remotehost
 
: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.
 
: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]]

Revision as of 19:34, 27 April 2020


Check network connectivity

netstat -nap
Show port status (LISTEN, ESTABLISHED, .....) and the program that owns it.
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 ]
   then
    echo No connection to ${TARGET}:${PORT}
  fi
done
wget <URL>
Get the data from <URL>

OpenSSL

See the OpenSSL page

Interfaces

ifconfig -a
Show all network interfaces
ifconfig <interface> <ipaddrss>
Assign <ipaddress> to <interface>
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>
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

For interfaces that may not be connected use allow-hotplug instead of auto.
The bootprocces now does not wait for an DCHP-answer on disconnected interfaces. Saves you about 5 minutes during startup.

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

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