Network Snippets

Network Snippets

Various snippets of code or one liners that I use often. Stuff that helps in day-2-day troubleshooting and whatnot.

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Linux Commands

What	CMD	AltCMD
Ping Default GW	Ping	Ping
Verify IP	ifconfig -a	ip a
Verify Link Up	ifconfig -a	ip a
Verify Default GW	netstat -rn	ip route
Verify Route Table	netstat -rn	ip route
Verify ARP Table	arp -an	ip neighbor

Windows Commands

What	CMD
Ping Default GW	Ping
Verify IP	ipconfig
Verify Link Up	ipconfig
Verify Default GW	netstat -rn
Verify Route Table	netstat -rn
Verify ARP Table	arp -a

Linux cmd to get public IP

curl ifconfig.io/ip

Linux cmd to get public IP continuously

while true; do curl ifconfig.io/ip; done

PowerShell cmd to get public IP and Country

curl ifconfig.io/ip | Out-String -Stream| Select-String "Content"
curl ifconfig.io/country_code | Out-String -Stream| Select-String "Content"

Cisco IOS command to show Assigned and UP interfaces

show ip int br | e unassigned|administratively

SSH Command to connect to older devices

If you’ve ever received the following message (or similar)

Unable to negotiate with 10.2.0.16 port 22: no matching key exchange method found. Their offer: diffie-hellman-group-exchange-sha1,diffie-hellman-group14-sha1

What you can do is tell SSH to use a (less secure) different exchange method

ssh -o KexAlgorithms=

curve25519-sha256                       diffie-hellman-group18-sha512           ecdh-sha2-nistp384
curve25519-sha256@libssh.org            diffie-hellman-group1-sha1              ecdh-sha2-nistp521
diffie-hellman-group14-sha1             diffie-hellman-group-exchange-sha1      sntrup4591761x25519-sha512@tinyssh.org
diffie-hellman-group14-sha256           diffie-hellman-group-exchange-sha256    
diffie-hellman-group16-sha512           ecdh-sha2-nistp256     

So then something like this will get you connected to the device via SSH

ssh -o KexAlgorithms=diffie-hellman-group14-sha1 admin@10.2.0.16

Counting the lines of Cisco IOS output

If you wanted to count the lines that a command outputs, you could do the following. For example, you want to count how many interfaces are connected. First thing that comes to mind is something like

SW-1#show int | inc connected  
GigabitEthernet1/0/2 is up, line protocol is up (connected) 
GigabitEthernet1/0/3 is up, line protocol is up (connected) 
GigabitEthernet1/0/5 is up, line protocol is up (connected) 
... 
GigabitEthernet2/0/49 is up, line protocol is up (connected) 
Port-channel1 is up, line protocol is up (connected) 

Which is nice, but if you just want a simple number then you can do the following

SW-1#show int | count connected      
Number of lines which match regexp = 41

Cleanup files on Windows

Not really a network thing, but useful none the less. Cleanup files on your Windows workstation

1.) Clear %TEMP%
2.) Clear C:\Windows\Temp
3.) Run cleanmgr.exe
4.) Run patchmypc.exe
5.) Delete stuff in %APPDATA% you don't have anymore

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Working with Git

Clone existing repo (remote, GitHub) to local server

git clone git@<YOUR-USER-NAME>/<YOUR-REPO-NAME>.git

Push local repo changes to remote GitHub repo

git add .
git commit -m "made some changes"
git push

Sync or Merge remote repo GitHub repo changes back to local repo

git pull

-eof-