[SOLVED] Can't ssh to a specific computer after upgrade

DJOtaku · 05-30-2015, 01:15 PM

I am having a weird issue that doesn't make sense with what I could find on google. When I try to ssh from my newly upgrade Fedora 22 to an Arch Linux machine, I get this error:

Code:

ssh root@babyluigi
Corrupted MAC on input.
ssh_packet_read: message authentication code incorrect

But I am able to SSH from this Fedora 22 machine to my VPS server on the Internet. And I can SSH to babyluigi from another Kubuntu machine on the network.

Everything is connected via my router and an ethernet switch. Fedora and babyluigi are on same switch. Kubuntu machine is on router that's connected to switch.

Thanks!

dt64 · 05-30-2015, 03:34 PM

first: I'm not a ssh expert, but if I had this eror I'd start with the following (aided by the first hits in Google:

This seems to explain some basics: https://blogs.oracle.com/janp/entry/...ode_bad_packet
Here is some bug description from WinSCP, which could guide the direction for the next steps: http://winscp.net/eng/docs/ui_login_...sh-2_hmac_keys
There is much more to read.

Which ssh server and version are your boxes running? Which settings apply?

DJOtaku · 06-03-2015, 08:08 PM

Quote:

Originally Posted by dt64

first: I'm not a ssh expert, but if I had this eror I'd start with the following (aided by the first hits in Google:

This seems to explain some basics: https://blogs.oracle.com/janp/entry/...ode_bad_packet
Here is some bug description from WinSCP, which could guide the direction for the next steps: http://winscp.net/eng/docs/ui_login_...sh-2_hmac_keys
There is much more to read.

Which ssh server and version are your boxes running? Which settings apply?

I saw those sites when I was googling before. Here is supermario, the one that suddenly can't ssh into babyluigi:

Code:

rpm -aq *ssh*
libssh-0.6.4-1.fc22.x86_64
erlang-ssh-17.4-1.fc22.x86_64
openssh-clients-6.8p1-6.fc22.x86_64
openssh-askpass-6.8p1-6.fc22.x86_64
openssh-6.8p1-6.fc22.x86_64
libssh2-1.5.0-1.fc22.x86_64
ksshaskpass-5.3.0-1.fc22.x86_64
libssh2-1.5.0-1.fc22.i686
openssh-server-6.8p1-6.fc22.x86_64

I also confirmed on another laptop with Fedora 22 (this time on wifi) cannot connect to babyluigi.

Going back to the computer that can connect, I see:

running pacman -Q openssh

gives

openssh 6.1p1-3

joec@home · 06-06-2015, 06:56 PM

I might suggest to flush the arp tables on both machines, as described in the following article. You can ignore adding static arp entries, very bad idea unless you seriously know exactly when and why to do so.

Clearing the arp cache in linux
http://g33kinfo.com/info/archives/4356

Also remove the stored RSA key for that IP address in the user cache trying to send the ssh request located in .ssh/known_hosts

Turbocapitalist · 06-07-2015, 03:15 AM

You mention that the old machine is running OpenSSH 6.1. Version 6.7 got rid of some insecure MACs. Can it be that it is using deprecated MACs and is in need of an upgrade?

joec@home · 06-07-2015, 02:43 PM

MAC is typically referring to the MAC Address embedded in the hardware of a network interface card. A bad MAC would imply that the data got corrupted on a MAC address request from one machine to another. See "arping man" for an example on the details. The least invasive thing to do first is to flush the ARP cache on the machines to ensure that the MAC is being retransmitted and not read from the TCP cache where the cache itself might be corrupted. I found an article describing the same error you are speaking of.

Corrupted MAC on input during ssh file transfer in Debian Linux
https://www.tty1.net/blog/2014/ssh-c...-input_en.html

DJOtaku · 06-10-2015, 07:08 AM

Quote:

Originally Posted by joec@home

I might suggest to flush the arp tables on both machines, as described in the following article. You can ignore adding static arp entries, very bad idea unless you seriously know exactly when and why to do so.

Clearing the arp cache in linux
http://g33kinfo.com/info/archives/4356

Also remove the stored RSA key for that IP address in the user cache trying to send the ssh request located in .ssh/known_hosts

I have removed the stored key and no dice there. I'll check out flushing the arp tables.

CynicRK · 06-16-2015, 10:26 AM

I had the same problem and fixed it by forcing ssh to use another mac method. My ssh communication used: umac-64@openssh.com (ssh -vvv username@pc) I changed to hmac-md5 (ssh -m hmac-md5 username@pc) and everyhing was working again.

DJOtaku · 06-24-2015, 02:49 PM

OK, I decided to upgrade and it worked. Until the next upgrade borked my system. So, I'm just letting people know for completion's sake - it was just an out of date ssh. Won't matter anymore, I'm moving to CentOS on a real computer where I can get to a console if things get messed up rather than Pogoplug with Arch breaking with every update.