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27 votes
Accepted

Do I really need a DB9-RJ45 adapter to connect to a Cisco router console, and if so, why?

While using a classical RJ45 jack, the connection on your Cisco router really is a RS232 serial connections. This means that, independently from the physical connector, your PC need to speek the same ...
shodanshok's user avatar
  • 50.9k
14 votes

What happens in the real world Internet - BGP and OSPF?

Typically, autonomous systems (ASNs) use an IGP (which can be OSPF, IS-IS or iBGP) so routers in their network know how to reach eachother. Networks connected to these routers and reachable through ...
Teun Vink's user avatar
  • 1,837
13 votes

How to find what is wearing out my SSDs

It’s hard to be certain without more details on the age of the systems, the exact model and age of the SSDs, and a handful of other factors. Assuming good quality SSDs, 1-2% on the wear indicator in a ...
Austin Hemmelgarn's user avatar
12 votes

Connect to switch's console port through ethernet patch panel

You should be able to connect the console port to the patch panel with a rollover cable. You must use a standard straight-through ethernet on the other end - NOT another rollover cable. If it's ...
Joshua Griffiths's user avatar
12 votes
Accepted

Connect to switch's console port through ethernet patch panel

Use a straight through cable from the console port of the Cisco to the patch panel, and then a rollover from the port in the wall to your computer?
Anthony Fornito's user avatar
11 votes

How to find what is wearing out my SSDs

Check swapping - that is a typical indicator. Check whether you run any temp files for whatever software - that may be another one. Both need you to check and given that temp files are software ...
TomTom's user avatar
  • 52k
10 votes

Cisco Anyconnect: Vpn establishment capability from a remote desktop is disabled

Connect to your computer via RDP. Create connect.dat file as following, finishing it with extra empty line (must-have requirement, sic!): connect your-VPN-server-here your-username-here your-password-...
Yury Schkatula's user avatar
10 votes

Cannot ssh into cisco switch: Invalid key length

openssh refuses the key length less than 1024 bits starting 7.6. https://www.openssh.com/txt/release-7.6 If you use ubuntu, you can install openssh-client-ssh1, then use ssh1 command instead of ssh. ...
Kevin's user avatar
  • 101
7 votes

VLAN sending data to ports it shouldnt have to

I noticed (based on activity lights) that VLAN traffic between two switch ports are being sent to many switch ports. Seriously? That's not how to determine traffic flows. The activity lights could be ...
joeqwerty's user avatar
  • 111k
7 votes
Accepted

How can I connect to a cisco switch via serial console cable from powershell?

Figured it out. Slap enter-pssession -computername XXXXXXX in front of this to remotely connect to a system to check. $com = New-Object System.IO.Ports.SerialPort(“COM1”) $com.open() $com.write([char]...
MathewC's user avatar
  • 7,017
7 votes
Accepted

Changing subnet mask to /23 from /24 on local network

The purpose of the prefix (and the deprecated netmask) is to define which part of the address space is on link. If a host has the wrong prefix configured, it will not be able to reach all of the ...
Michael Hampton's user avatar
7 votes

Subnet mask for 192.168.1.7/30

With 192.168.1.7 255.255.255.252, the addresses range from 192.168.1.4 - 192.168.1.7. 192.168.1.4 is the network address. 192.168.1.7 is the broadcast address. You cannot apply either of those 2 ...
Bib's user avatar
  • 221
6 votes
Accepted

RIP versus OSPF

Administrative distance is the feature that routers use in order to select the best path when there are two or more different routes to the same destination from two different routing protocols. ...
stambata's user avatar
  • 1,718
6 votes

Recover from Cisco ASA 5508-X internal flash failure?

The boot flash (disk0) on that is an internal eUSB. I don't have a 5508-X handy to see if it can be swapped out easily or if it was soldered in. You might be able to get away with using a USB thumb ...
rnxrx's user avatar
  • 8,163
6 votes
Accepted

Do 10GbE SFP transceivers need to match?

Simple answer: No. You don't need to match Brand or Model, 10GbE is usually not as picky as FC.
bjoster's user avatar
  • 4,957
5 votes

Cisco SG200-26 - Can't change management VLAN

It's a catch 22 if you are plugged into the management port - the switch won't let you change management VLAN if nothing is plugged into one of those ports. It might be trying to prevent you to lock ...
ServerGuy0328's user avatar
5 votes

Linux bond mode 802.3ad not activated

Old question, but since it comes up pretty early in searches, and I had a similar setup, with the same problem. Here's how I got it working, (using ifenslave on Debian stretch)... /etc/network/...
Radar's user avatar
  • 51
5 votes
Accepted

How to find what is wearing out my SSDs

You can use ProcMon for Linux to trace file system calls. https://github.com/Sysinternals/ProcMon-for-Linux
Greg Askew's user avatar
4 votes

Cisco Anyconnect: Vpn establishment capability from a remote desktop is disabled

The fix for this issue is start the VPN session using the "Basic mode" (disabling the "Enhanced session" option). It worked for me. Look this post: https://foxdeploy.com/2015/11/20/solved-cisco-...
Esteban Viveros's user avatar
4 votes
Accepted

LACP Trunk from Cisco to Fortinet

If the way i have done is not true LACP, how come it is working with the Fortinet (which is set for 802.3ad Aggregate)? Seems setting channel-protocol lacp on my ports makes no difference (is it LACP ...
YLearn's user avatar
  • 1,247
4 votes

Cisco native port has to be included in allowed vlans of trunk

Reference: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus5000/sw/configuration/guide/cli/CLIConfigurationGuide/AccessTrunk.html#18749 Emphasis mine: By default, a trunk port sends ...
Todd Wilcox's user avatar
  • 2,871
4 votes
Accepted

How to screengrab from Cisco SPA504g phone?

I'd given up on this, but stumbled across the answer: http://*phone-ip-address*/admin/screendump.bmp Ref from Cisco forums. Tested today on SPA504G with software version 7.6.2a. It's correct right ...
jonathanjo's user avatar
4 votes

How does a client choose between two DHCP servers in the same network?

DHCP is first-come, first-serve. You should not have two competing DHCP servers on the same network without some form of fail-over or HA between them, otherwise you run the risk of having duplicate IP'...
Andrew's user avatar
  • 2,182
4 votes

Cannot ssh into cisco switch: Invalid key length

If your getting the "Invalid key length" error, the problem isn't your Ciphers (that may be it's own problem, but if you're getting a key, SSH has agreed to a Cipher) I read the CISCO documentation ...
Gregory McPhee's user avatar
4 votes
Accepted

Can I make cisco router to act like a radius server?

You are missing the server. No you can't set the router as a server. Local auth is not RADIUS. The whole point of a RADIUS is to use a different machine for authentication purpose. The IP you set with ...
Overmind's user avatar
  • 3,171
4 votes
Accepted

Bad mask /30 for address 10.1.1.3 || Cisco P.T

10.1.1.3/30 is the directed broadcast address for that subnet and as such, it isn't usable as host address. You can use 10.1.1.1 and 10.1.1.2 from that subnet. If you do need to use 10.1.1.3 you need ...
Zac67's user avatar
  • 11.9k
3 votes

Cisco AnyConnect on Linux disable resolv.conf update

Newer versions of AnyConnect (above 4.3.05017 as mentioned by @David G) fails when not being able to modify /etc/resolv.conf. What worked for me was to modify the binary of /opt/cisco/anyconnect/bin/...
Emsi's user avatar
  • 131
3 votes

How to configure Cisco VPNUI shortcut to open a specific host?

Hi i tried a lot of things and the below is what worked for me To connect to cisco anyconnect vpn using commandline from windows: Install anyconnect using the installer In powershell create a file ...
Sharath Prakash's user avatar
3 votes

Cisco ASA5505 - icmp deny any outside breaks internet - how to block outside pings?

What you're missing is: First, ICMP, at least in part, is required for proper functioning of the Internet. Second, blocking pings is completely pointless; it has no security benefits whatsoever, and ...
Michael Hampton's user avatar
3 votes

Is information transmitted over Cisco routers saved anywhere on the router itself?

Sure, for microseconds it lives in some buffers so that the routers can check it against ACLs and match it against its routing tables (technically it only needs the headers for performing these ...
Mark Henderson's user avatar

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