X11 over SSH

[Christos Ricudis]

Se kapoia douleia, xreiasthke na sthsw ena periballon sto opoio oi 
perissoteroi users xrhsimopoioyn X apo to PC toys. Gia logous asfaleias, 
toys anagkazw na kanoyn tunnel to X protocol panw apo SSH, pragma poy exei 
ena sxetika shmantiko performance overhead, to opoio ginetai enoxlhtiko
otan o mesos xrhsths anoigei ena ghostview me ena postscript arxeio 20
Mbytes. 

Dokimasa toys perissoterous syndiasmous metaksy OpenSSH 2.9, SSH 3.01,
compiled me GNU C h toys native compilers ths DEC kai ths SUN, kai ta
yposthrizomena ciphers (nai, eimai diestrammenos kai exw poly eley8ero
xrono). 

Ekana kapoia benchmarks me to X11perf, kai ebgala arketa endiaferonta 
symperasmata, ta pio shmantika ek twn opoiwn einai ta parakatw : 

* Akomh kai xwris encryption, to SSH X11 tunneling exei ena shmantiko
performance impact - ta workloads poy metrhsa petyxan maximum to 1/3 ths 
apodoshs poy exoun kanonika xwris tunneling. 

* To SSH compression boh8aei shmantika - oxi toso bebaia oso enas X11
protocol aware compressor, alla paizei rolo. 

* Opws to perimena kai apo th 8ewria, yparxoun shmantikes diafores sthn 
taxythta twn diaforwn ciphers. To blowfish apodeixthke to kalytero apo
pleyras performance, kai malista me arketh diafora. To twofish einai elafrws
pio grhgoro, alla deite parakatw. 

* Periergws, o syndiasmos OpenSSH server / OpenSSH client apodeixthke 
POLY grhgoroteros apo to SSH se oles tis periptwseis kai se olous toys 
syndiasmous server/client, compilation, kai encryption. Ayto, akoma kai an
analogistoume to gegonos oti to SSH parexei kapoia ciphers poy einai 
grhgorotera apo ayta poy parexei to OpenSSH. 

* Akomh pio periergo htan to gegonos oti KAI to OpenSSH KAI to SSH protimane
- apo pleyras performance - na ginontai compile me thn GNU C para me toys
native platform compilers. Omologw oti edw mporei na kanw la8os, giati den 
dokimasa kanena apo ta 8eopalaba optimization options poy exoyn oi
commercial compilers, pera apo to aplo -O2 

* Se mia periptwsh, to benchmark apodeixthke grhgorotero over the network 
metaksy enos XFree86 client kai enos Xsun server, para otan to etreksa 
locally sto XFree86 mhxanhma.

* Teleytaio kai shmantikotero symperasma : Ola ayta einai kala kai omorfa
oso exoume UNIX mhxanhmata kai sta dyo akra. Otan o X server trexei se
windows, to performance einai toso fucking disgustingly dissapointing pou
opoio syndiasmo X server/client/cipher/tunnel/compiler/magou fylarxou X11 
guru epilekseis, den exei kammia praktikh shmasia. :> 

Exei kanei kaneis sas analoges dokimes? 



 






-- 

Christos Ricudis				ricudis at lemnos.geo.auth.gr
Systems Administrator				+30-310-998534
Geophysics Department
Faculty of Geology
Aristotles University of Thessaloniki,GREECE