March 2010
14 posts
1 tag
EDNS0 DNS PMTU
EDNS pmtu calculation:
$ dnsfunnel -t A @c.dns.gandi.net packetfault.org 217.70.182.20 4096B 0.001536 217.70.182.20 2304B 0.001531 217.70.182.20 1408B 0.001587 217.70.182.20 960B 0.001484 217.70.182.20 736B 0.001468 217.70.182.20 624B 0.001484 217.70.182.20 568B 0.001468 217.70.182.20 540B 0.001444 217.70.182.20 526B 0.001635 217.70.182.20 519B ...
1 tag
BGP ASN collision
Gem from the past:
% whois -h whois.ripe.net AS1712
aut-num: AS1712
as-name: FR-RENATER-ENST
descr: Ecole Nationale Superieure des Telecommunications,
descr: Paris, France.
descr: FR
% whois -h whois.arin.net AS1712
OrgName: Twilight Communications
City: Wallis
StateProv: TX
Country: US
oups!
1 tag
The great firewall block dns g root server
The great firewall of China block the g root serv0r
http://www.cymru.com/monitoring/dnssumm/index.html
2 tags
Behavior caused by bad programming (or not)
Sometimes I play with Cisco IOS and stuff occurs despite my will…
A14-7206#dir nvram: Directory of nvram:/ %Error calling getdents for nvram:/ (Device or resource busy) 129016 bytes total (111124 bytes free)
Astalavista… IOS!
1 tag
“6 stages of debugging: 1) can’t happen 2) doesn’t repro 3)...”
– FX
IOStrojan: Who really owns your router? http://bit.ly/dn0QTR #sans #cisco #tcl
1 tag
whois AS number
$ whois AS23724
Don’t play with this AS! it’s EVIL!
1 tag
python debuggers
A list of python debuggers I found with my google-fu:
pdb (pdb.set_trace), pydb, winpdb, gdb (pystack..for debugging python himself), ddd
1 tag
python pdb is your friend
Yo! python debugger pdb in da place for handling npeid issue.
Little debugger but helpful :)
imhidden@Networker:/home/hidden# ./npeid.py
> /home/hidden/npeid.py(18)handleTcpStream()
-> toserver = tcp.server.data[:tcp.server.count]
(Pdb) n
> /home/hidden/npeid.py(19)handleTcpStream()
-> toclient = tcp.client.data[:tcp.client.count]
(Pdb) n
>...
1 tag
How to reset Internet Protocol (TCP/IP) →
1 tag
VMWARE virtual networking concepts →
1 tag
tcp timestamps
TCP timestamps notes:
rfc1323
Timestamps: TSval 4125101209, TSecr 0 (SYN)
Timestamps: TSval 15477599, TSecr 4125101209 (SYN/ACK)
No timestamps with RST pkts (Linux 2.6.31 stack)
No timestamps with SYN&SYN/ACK (windows … need to be tested with win7)
Bad: rttm only when the tcp window is low. Not realistic. Lead to introducing “aliasing” artifacts into the estimated RTT....
1 tag
traceroute nanog version
Determine route of packets in TCP/IP networks (NANOG variant) This is the traceroute program maintained by Ehud Gavron. It is based on the Van Jacobson/BSD traceroute and has additional features like AS lookup, TOS support, microsecond timestamps, path MTU discovery, parallel probing and others. The NANOG traceroute upstream FTP archive can be found at ...
1 tag
