Liberating SSH from Logjam leftovers

A recent Request for Comment at the Internet Engineering Task Force calls for SSH developers to deprecate 1,024-bit moduli. RFC 8270 was authored by Mark Baushke (at Juniper Networks but working as an individual*) and Loganaden Velvindron (of Mauritian group Hackers.mu) in response to demand for a response to the 2015 Logjam …

[A Non e-mouse]

Cisco

Cisco need to step up to the plate here: Some of their IOS kit either only works with 1024 bit SSH keys and others have weird bugs if you don't use 2048 SSH keys.

[Alan J. Wylie]

Better still, use Elliptic Curve

Some useful advice on hardening ssh, from 2 and a half years ago:

https://stribika.github.io/2015/01/04/secure-secure-shell.html

And a program to test an ssh server:

https://github.com/arthepsy/ssh-audit

djb rules, OK

# key exchange algorithms

(kex) [e-mail] -- [info] available since OpenSSH 6.5, Dropbear SSH 2013.62

# host-key algorithms

(key) ssh-ed25519 -- [info] available since OpenSSH 6.5

# encryption algorithms (ciphers)

(enc) [e-mail] -- [info] available since OpenSSH 6.5

`- [info] default cipher since OpenSSH 6.9.

[chasil]

detect, fix

I wasn't expecting this, but 1024/1535 bit primes are in the latest CentOS.

# fgrep ' 1023 ' /etc/ssh/moduli | wc -l

29

# fgrep ' 1535 ' /etc/ssh/moduli | wc -l

49

This "in-place" sed edit command will remove them (restart sshd after edit):

sed -i.BAK 's/^.*[ ]1023[ ]/#&/;s/^.*[ ]1535[ ]/#&/' /etc/ssh/moduli

[bob, mon!]

2048 bits????

640 bits should be enough for anyone...

oh wait. wrong thread.

[david 12]

HTTP internet is disapearing before my eyes

6 months ago I could still connect from devices that only supported 256 bit encryption -- because I could still use HTTP. In the last 6 months that's shrunk down to a few pixels in the big picture -- large chunks of the internet no longer support HTTP.