Debian, Ubuntu, and Raspbian Mirror at ETH Zurich

Reachable as debian.ethz.ch HTTP HTTPS FTP
ubuntu.ethz.ch HTTP HTTPS FTP
raspbian.ethz.ch HTTP HTTPS FTP
ftp.ch.debian.org HTTP HTTPS FTP

HTTPS Access

While we would like to provide HTTPS access for all hostnames pointing to this mirror, Debian prefers having primary mirrors to not have HTTPS for their ftp.*.debian.org hostname.

If you prefer to access this Debian mirror via HTTPS, please replace https://ftp.ch.debian.org/ by https://debian.ethz.ch/ in your sources.list file.

[ICO]NameLast modifiedSizeDescription
[PARENTDIR]Parent Directory  -  
[ ]charon-cmd_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 95K 
[ ]charon-cmd_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 95K 
[ ]charon-cmd_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 94K 
[ ]charon-cmd_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 95K 
[ ]charon-cmd_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 100K 
[ ]charon-cmd_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 100K 
[ ]charon-cmd_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 99K 
[ ]charon-cmd_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 99K 
[ ]charon-cmd_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 100K 
[ ]charon-cmd_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 100K 
[ ]charon-cmd_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 99K 
[ ]charon-cmd_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 101K 
[ ]charon-cmd_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 99K 
[ ]charon-systemd_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 91K 
[ ]charon-systemd_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 92K 
[ ]charon-systemd_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 91K 
[ ]charon-systemd_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 92K 
[ ]charon-systemd_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 96K 
[ ]charon-systemd_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 96K 
[ ]charon-systemd_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 96K 
[ ]charon-systemd_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 96K 
[ ]charon-systemd_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 97K 
[ ]charon-systemd_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 96K 
[ ]charon-systemd_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 96K 
[ ]charon-systemd_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 97K 
[ ]charon-systemd_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 96K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 101K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 100K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 100K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 100K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 101K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 100K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 100K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 101K 
[ ]libcharon-extauth-plugins_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 100K 
[ ]libcharon-extra-plugins_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 244K 
[ ]libcharon-extra-plugins_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 238K 
[ ]libcharon-extra-plugins_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 225K 
[ ]libcharon-extra-plugins_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 260K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 259K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 252K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 237K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 239K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 277K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 243K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 244K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 271K 
[ ]libcharon-extra-plugins_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 249K 
[ ]libstrongswan-extra-plugins_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 248K 
[ ]libstrongswan-extra-plugins_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 238K 
[ ]libstrongswan-extra-plugins_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 242K 
[ ]libstrongswan-extra-plugins_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 258K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 258K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 249K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 247K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 244K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 269K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 251K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 262K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 261K 
[ ]libstrongswan-extra-plugins_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 252K 
[ ]libstrongswan-standard-plugins_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 138K 
[ ]libstrongswan-standard-plugins_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 124K 
[ ]libstrongswan-standard-plugins_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 118K 
[ ]libstrongswan-standard-plugins_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 145K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 144K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 130K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 125K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 125K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 150K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 127K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 127K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 136K 
[ ]libstrongswan-standard-plugins_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 130K 
[ ]libstrongswan_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 412K 
[ ]libstrongswan_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 399K 
[ ]libstrongswan_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 370K 
[ ]libstrongswan_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 434K 
[ ]libstrongswan_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 427K 
[ ]libstrongswan_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 411K 
[ ]libstrongswan_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 379K 
[ ]libstrongswan_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 386K 
[ ]libstrongswan_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 452K 
[ ]libstrongswan_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 390K 
[ ]libstrongswan_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 391K 
[ ]libstrongswan_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 443K 
[ ]libstrongswan_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 408K 
[ ]strongswan-charon_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 95K 
[ ]strongswan-charon_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 95K 
[ ]strongswan-charon_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 94K 
[ ]strongswan-charon_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 95K 
[ ]strongswan-charon_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 100K 
[ ]strongswan-charon_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 101K 
[ ]strongswan-charon_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 100K 
[ ]strongswan-libcharon_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 305K 
[ ]strongswan-libcharon_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 295K 
[ ]strongswan-libcharon_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 275K 
[ ]strongswan-libcharon_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 338K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 317K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 302K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 282K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 286K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 350K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 284K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 287K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 329K 
[ ]strongswan-libcharon_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 299K 
[ ]strongswan-nm_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 96K 
[ ]strongswan-nm_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 96K 
[ ]strongswan-nm_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 94K 
[ ]strongswan-nm_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 98K 
[ ]strongswan-nm_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 103K 
[ ]strongswan-nm_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 102K 
[ ]strongswan-nm_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 101K 
[ ]strongswan-nm_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 101K 
[ ]strongswan-nm_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 104K 
[ ]strongswan-nm_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 102K 
[ ]strongswan-nm_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 102K 
[ ]strongswan-nm_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 105K 
[ ]strongswan-nm_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 102K 
[ ]strongswan-pki_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 126K 
[ ]strongswan-pki_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 127K 
[ ]strongswan-pki_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 125K 
[ ]strongswan-pki_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 128K 
[ ]strongswan-pki_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 132K 
[ ]strongswan-pki_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 132K 
[ ]strongswan-pki_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 130K 
[ ]strongswan-pki_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 131K 
[ ]strongswan-pki_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 134K 
[ ]strongswan-pki_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 130K 
[ ]strongswan-pki_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 130K 
[ ]strongswan-pki_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 138K 
[ ]strongswan-pki_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 130K 
[ ]strongswan-scepclient_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 100K 
[ ]strongswan-scepclient_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 100K 
[ ]strongswan-scepclient_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 99K 
[ ]strongswan-scepclient_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 100K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 105K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 105K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 104K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 104K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 105K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 105K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 105K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 105K 
[ ]strongswan-scepclient_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 105K 
[ ]strongswan-starter_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 223K 
[ ]strongswan-starter_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 220K 
[ ]strongswan-starter_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 215K 
[ ]strongswan-starter_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 229K 
[ ]strongswan-starter_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 223K 
[ ]strongswan-starter_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 220K 
[ ]strongswan-starter_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 214K 
[ ]strongswan-starter_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 215K 
[ ]strongswan-starter_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 229K 
[ ]strongswan-starter_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 217K 
[ ]strongswan-starter_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 218K 
[ ]strongswan-starter_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 229K 
[ ]strongswan-starter_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 217K 
[ ]strongswan-swanctl_5.7.2-1+deb10u3_amd64.deb2022-10-10 18:42 180K 
[ ]strongswan-swanctl_5.7.2-1+deb10u3_arm64.deb2022-10-10 19:27 179K 
[ ]strongswan-swanctl_5.7.2-1+deb10u3_armhf.deb2022-10-10 19:27 172K 
[ ]strongswan-swanctl_5.7.2-1+deb10u3_i386.deb2022-10-10 19:27 190K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_amd64.deb2022-10-06 10:27 188K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_arm64.deb2022-10-06 10:27 186K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_armel.deb2022-10-06 10:42 179K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_armhf.deb2022-10-06 10:27 180K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_i386.deb2022-10-06 10:17 197K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_mips64el.deb2022-10-06 10:42 179K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_mipsel.deb2022-10-06 10:27 180K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_ppc64el.deb2022-10-06 10:27 195K 
[ ]strongswan-swanctl_5.9.1-1+deb11u3_s390x.deb2022-10-06 10:17 180K 
[ ]strongswan_5.7.2-1+deb10u3.debian.tar.xz2022-10-10 18:42 117KDebian APT repository (oldstable, stable, testing, unstable, experimental, lts, backports)
[TXT]strongswan_5.7.2-1+deb10u3.dsc2022-10-10 18:42 3.2K 
[ ]strongswan_5.7.2-1+deb10u3_all.deb2022-10-10 18:42 91K 
[ ]strongswan_5.7.2.orig.tar.bz22021-10-15 17:33 4.8M 
[ ]strongswan_5.9.1-1+deb11u3.debian.tar.xz2022-10-06 09:57 119KDebian APT repository (oldstable, stable, testing, unstable, experimental, lts, backports)
[TXT]strongswan_5.9.1-1+deb11u3.dsc2022-10-06 09:57 3.2K 
[ ]strongswan_5.9.1-1+deb11u3_all.deb2022-10-06 10:17 96K 
[ ]strongswan_5.9.1.orig.tar.bz22021-10-15 17:23 4.4M 
[ ]strongswan_5.9.1.orig.tar.bz2.asc2021-10-15 17:23 648  

Sample /etc/apt/sources.list with HTTPS:

deb https://debian.ethz.ch/debian stable main contrib non-free
deb-src https://debian.ethz.ch/debian stable main contrib non-free

Sample /etc/apt/sources.list without HTTPS:

deb http://debian.ethz.ch/debian stable main contrib non-free
deb-src http://debian.ethz.ch/debian stable main contrib non-free

Inoffical Security Mirror

Reachable as security.debian.ethz.ch HTTP HTTPS FTP

Our security mirror is no official security mirror and only thought as local cache. See the Debian Security FAQ for reasoning.

Its updates are not triggered by a push, hence the mirror may be out of date. If you want to use it, we suggest to use it like this (you can also use HTTP instead of HTTPS if you want):

Debian 11 "Bullseye" or newer

deb https://security.debian.ethz.ch/ stable-security main contrib non-free
deb http://security.debian.org/ stable-security main contrib non-free

Debian 10 "Buster" or older

deb https://security.debian.ethz.ch/ buster/updates main contrib non-free
deb http://security.debian.org/ buster/updates main contrib non-free

So if this security mirror already has the updated package mirrored, it's fetched from there as it's the first hit for the newest version. If not, the newest package is still already available and fetched from the official servers.

Use at your own risk!

Access by Alternative Protocols

Alternative access by FTP is possible.

Alternative access by HTTPS is possible for all *.ethz.ch hostnames.

The main Debian archives are accessible by rsync:

  • rsync debian.ethz.ch::debian
  • rsync debian.ethz.ch::debian-cd
  • rsync debian.ethz.ch::debian-archive

Additionally, also the following archives are available by rsync:

  • rsync debian.ethz.ch::raspbian
  • rsync debian.ethz.ch::ubuntu

About and Contact

This server is one of the official Debian mirrors (status of the Debian mirror network) and also known as ftp.ch.debian.org.

In case of problems with this specific mirror, please contact the IT Services Group (ISG) of the Dept. of Physics at ETH Zurich, preferably by e-mail to mirror@phys.ethz.ch.