Category Archives: Networking

When Is A Trunk Not A Trunk?

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Very good article here – http://networkingnerd.net/2011/02/02/when-is-a-trunk-not-a-trunk/

Particuly like setting of Native vLAN and tagged networks over an HP trunk;

So, if HP refers to an uplink carrying multiple VLANs are a tagged port, then does HP have a “trunk”? In fact they do. In HPvania, a trunk is a logical construct that aggregates multiple ports into one logical link. For those of you that might be out there scratching your heads about this one, this means that when you “trunk” a group of ports on an HP switch, you are creating one LACP link from up to four individual ports. This kind of configuration should look like this:

Switch(config)#trunk 19-24
Switch(config)#trk1
Switch(config-trk)#lacp
Switch(config-trk)#vlan 1
Swtich(config-vlan)#untagged trk1
Swtich(config-vlan)#vlan 10
Swtich(config-vlan)#tagged trk1
Swtich(config-vlan)#vlan 99
Swtich(config-vlan)#tagged trk1

Those of you that are fans of irony will appreciate that the above config sets up this LACP port aggregation to pass multiple VLANs to another switch. In other words, we are configuring a Cisco “trunk” on top of an HP “trunk”.

squid – reverse proxy

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Great guide here – http://www.classhelper.org/articles/reverse-proxy-server-squid-debian/installing-squid-proxy-server.shtml

I’ve modified slightly for Ubuntu, but almost identical.

apt-get install squid
cp /etc/squid3/squid.conf /etc/squid3/squid.bak
rm /etc/squid3/squid.conf
nano /etc/squid/squid.conf

http_port 80 defaultsite=www.yoursite.com vhost
forwarded_for on
refresh_pattern ^ftp: 1440 20% 10080
refresh_pattern ^gopher: 1440 0% 1440
refresh_pattern . 0 20% 4320
cache_peer 192.168.0.13 parent 80 0 no-query no-digest originserver name=web1
acl sites_web1 dstdomain www.yoursite.com yoursite.com
cache_peer_access web1 allow sites_web1
cache_peer 192.168.0.14 parent 80 0 no-query no-digest originserver name=web2
acl sites_web2 dstdomain www.anothersite.com anothersite.com
cache_peer_access web2 allow sites_web2
acl all src 0.0.0.0/0.0.0.0
acl manager proto cache_object
acl localhost src 127.0.0.1/255.255.255.255
acl to_localhost dst 127.0.0.0/8
acl SSL_ports port 443
acl Safe_ports port 80 # http
acl Safe_ports port 443 # https
acl Safe_ports port 1025-65535 # unregistered ports
acl CONNECT method CONNECT
http_access allow sites_web1
http_access allow sites_web2
http_access allow manager all
http_access allow manager
http_access deny !Safe_ports
http_access deny CONNECT !SSL_ports
#http_access deny all
access_log /var/log/squid3/access.log
cache_mgr [email protected]

 

Modify your hosts file to include web1 and web2

nano /etc/hosts

192.168.0.13 web1
192.168.0.14 web2

Another good article about benefits of reverse proxy

http://2bits.com/articles/increasing-drupals-speed-squid-caching-reverse-proxy.html

Using netsh to create a transparent proxy

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There are some good windows web proxies about. The only problem with them is they sometimes dont natively act as a transparent proxy. i.e. typically you’ll need to set your client machines to a specific IP and port.

I’ve used squid historically when setting up transparent proxies (mainly since it actually has a transparent mode) and this has worked well. Recently i thought i’d have a go at some of the windows solutions to see how they pan out.

netsh is going to be the tool to assist in this case. Here is a typical use for netsh;

netsh

>add v4tov4 listenport=80 connectaddress=127.0.0.1  connectport=8080

This should grab all traffic that hits your machine bound for port 80 and redirect to port 8080.

You’ll also need to make sure that routing is enabled, so your machine can act as a gateway between the requests and the real outbound gateway (typically your dsl modem)

opensolaris – setting up dhcp

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You’ll need these two packages installed;

SUNWdhcs, SUNWdhcm

First ensure that the DHCP service is running. Go into the “services” gui and tick the box to enable the DHCP server.

now from commandline run…

dhcpmgr
  1. From edit menu choose “network wizard”, step through the wizard (defautls are o.k i you have a fixed IP already assigned to your opensolaris box)
  2. From edit menu choose “address wizard”

If you step through the wizard (the following is an example of what i have choosen)

  1. Choose Text files
  2. Leave default path of /var/dhcp
  3. Do not manage hosts records
  4. Default lease of 1 day (clients can renew their leases)
  5. DNS Domain “yourdomainname”, also add your DNS here
  6. Network Address & subnet (should be pre populated if you have fixed IP on your host)
  7. Network Type (LAN), Routing (leave as default)
  8. I have left NIS blank
  9. I have left NIS+ blank