User jack logs in to host solar in and issues the following command: jack@solaris:-$ ls .ssh
id_dsa id_dsa.pub id_rsa id_rsa.pub known_hosts authorized_keys
Which two are true?
Correct Answer: A,E
A: You will see two files starting with id_rsa. id_rsa is the private key and id_rsa.pub is public key.
E: The .ssh/known_hosts file
In order to use public-key secure connection with other hosts (ssh, scp, sftp) there is a special directory, ~/.ssh/, where passphrases and public keys are stored. Normally you wouldn't need to know the gory details, but from time to time a host will change its public key and then you have difficulty using ssh or scp with that host, and have to edit a file named known_hosts. If you try to ssh to another computer, but get an error message that warns about a changed or incorrect public key, then it is probably just a case of that host changing its public key. (It is possible, though usually not the case, that malicious hacking is involved.) Unless you actually suspect hacker involvement, you can edit the file ~/.ssh/known_hosts using your usual text editor (vi, emacs, nedit, or pico) and delete any line with the name of that host.
Then when you try to ssh that host again, it will be like the first time ever; ssh will ask you if you want to accept a new public key, you type the whole word yes, and everything will proceed normally from there.
Here is what a typical ~/.ssh/known_hosts file might contain. Note that newton is represented on two different lines:
newton 1024 35 153438062610297067329638677441205712613292203533062535600064224677647442245028 855505387934431717435134842994423656065076260604296084868001730665553662299156 116414854701274715680961503198280525759778667306417179500370189017139564144825 610347509023078143132936185076849630461827976942220442313116255293297021841 ucsub 1024 37 132170811640421742212085598383135714069016332111955003414250071326834884018721 183646445780180633494496866895830879394309011412231102757022090299732775466435 482517698989962531081214859205054227533597152962802400251809883548442498002326 460312850336779152617243800769119880843882425555806081435017335194477605333 simpson 1024 41 840896920592494584403453622735282634536002054701576247765078766974814128393752 943151071629834843909016027026612791643752972116459602750267266908365259665072 736159491719667576217171370458928680504368847255632477925660234893185547218857 65548457461907512536847079297627580626353420887972219277539015703446529603 newton, 128.138.249.8 ssh-rsa AAAAB3NzaC1yc2EAAAABIwAAAIEA0d7Aoure0toNJ+YMYi61QP2ka8m5x5ZQlT7obP8CK3eropf qsMPPY6uiyIh9vpiFX2r1LHcbx139+vG6HOtVvuS8+IfMDtawm3WQvRuOopz3vVy5GtMwtaOgehs XoT930Ryev1bH5myPtWKlipITsOd2sX9k3tvjrmme4KCGGss=
Reference: How to Generate a Public/Private Key Pair for Use With Solaris Secure Shell
