An aide-memoir for PMTU operation.
Usually, the path MTU is determined using MTU Path Discovery. Usually, two hosts can dynamically negotiate the path MTU (e.g. client and server ) but networks that contain firewalls or tunnels (VPN, GRE, IPSec transport mode) sometimes require tuning the MTU values manually. Read more…
Normal TCP options are Type 0 (End of Option List), 1 (No-Operation), 2 (Maximum Segment Size, len 4), 3 (WSOPT – Window Scale, len 3), 4 (SACK Permitted, len 2), 5 (SACK, len N), and 8 (TSOPT – Time Stamp Option, len 10). Read more…
Simple and Protected GSSAPI Negotiation Mechanism (SPNEGO)
1. A client requests (HTTP GET) a page from a server;
2. The server returns HTTP code 401 along with a header: “WWW-Authenticate: Negotiate” (Authentication Required, and we can negotiate);
3. The client the re-sends the request (HTTP GET) but this time with an authorisation header (“Authorization: Negotiate “) along with three “MechTypes” (for example MS Kerberos 5, Kerberos 5 and NTLMSSP);
4. The server authenticates the client using one of the MechTypes (for example “supportedMech” used may be for an IIS server MS Kerberos 5), returning an HTTP 200 (OK) along with the last authenticate header plus the data requested.
Read more…
Who invented Ethernet? Robert Metcalfe got the idea for the Ethernet protocol when he read a 1970 computer conference paper by Norman Abramson of the University of Hawaii about the packet radio system called ALOHAnet linking the Hawaiian Islands: Read more…
To install IPv6:
Start, point to All Programs, point to Accessories, and then click Command Prompt.
At the command prompt, type: ipv6 install and press the Enter Key.
To uninstall IPv6:
Start, point to All Programs, point to Accessories, and then click Command Prompt.
At the command prompt, type:netsh int ipv6 uninstall and press the Enter Key.
Ever had that problem where the ant.com toolbar appear in your HTTP user Agent? You tried to find it and remove it; you tried “add/remove programs” in Windows; you looked in Firefox Addons – but you couldn’t find it!
Try this:
- Open Firefox and in the address bar, enter “about:config” then hit enter.
- Now, in the filter, enter “general:useragent”
- You might find your user agent, containing the ant.com toolbar. If this is the case, right-click on the entry and choose “reset”.
(Always excercise caution when working with advanced settings).
Ever bought one of those APC Masterswitch PDU’s from eBay, then tried to login to the admin interface with the usual default “apc” / “apc” but found that the password had been changed?
Manuals:
The usual password recovery procedures (well documented) are quite tedious, requiring emails and serial numbers. What a pain!
- If you use one in your home lab this vulnerability will help you if you happen to buy one from eBay with the password set.
- If you use them on a production network – this could become an attack vector, so replace them or upgrade!
Here’s how to hack the password: Read more…
