From 91729e3501d53d11fcc7a364b36994305c495945 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Sun, 9 Feb 2014 16:10:06 +0000 Subject: Add DebianBanner server configuration option Setting this to "no" causes sshd to omit the Debian revision from its initial protocol handshake, for those scared by package-versioning.patch. Bug-Debian: http://bugs.debian.org/562048 Forwarded: not-needed Last-Update: 2015-08-19 Patch-Name: debian-banner.patch --- servconf.c | 9 +++++++++ servconf.h | 2 ++ sshd.c | 3 ++- sshd_config.5 | 5 +++++ 4 files changed, 18 insertions(+), 1 deletion(-) diff --git a/servconf.c b/servconf.c index 8a5bd7b..fe3e311 100644 --- a/servconf.c +++ b/servconf.c @@ -169,6 +169,7 @@ initialize_server_options(ServerOptions *options) options->ip_qos_bulk = -1; options->version_addendum = NULL; options->fingerprint_hash = -1; + options->debian_banner = -1; } /* Returns 1 if a string option is unset or set to "none" or 0 otherwise. */ @@ -347,6 +348,8 @@ fill_default_server_options(ServerOptions *options) options->fwd_opts.streamlocal_bind_unlink = 0; if (options->fingerprint_hash == -1) options->fingerprint_hash = SSH_FP_HASH_DEFAULT; + if (options->debian_banner == -1) + options->debian_banner = 1; /* Turn privilege separation on by default */ if (use_privsep == -1) use_privsep = PRIVSEP_NOSANDBOX; @@ -419,6 +422,7 @@ typedef enum { sAuthenticationMethods, sHostKeyAgent, sPermitUserRC, sStreamLocalBindMask, sStreamLocalBindUnlink, sAllowStreamLocalForwarding, sFingerprintHash, + sDebianBanner, sDeprecated, sUnsupported } ServerOpCodes; @@ -565,6 +569,7 @@ static struct { { "streamlocalbindunlink", sStreamLocalBindUnlink, SSHCFG_ALL }, { "allowstreamlocalforwarding", sAllowStreamLocalForwarding, SSHCFG_ALL }, { "fingerprinthash", sFingerprintHash, SSHCFG_GLOBAL }, + { "debianbanner", sDebianBanner, SSHCFG_GLOBAL }, { NULL, sBadOption, 0 } }; @@ -1850,6 +1855,10 @@ process_server_config_line(ServerOptions *options, char *line, options->fingerprint_hash = value; break; + case sDebianBanner: + intptr = &options->debian_banner; + goto parse_int; + case sDeprecated: logit("%s line %d: Deprecated option %s", filename, linenum, arg); diff --git a/servconf.h b/servconf.h index b99b270..ba7b739 100644 --- a/servconf.h +++ b/servconf.h @@ -196,6 +196,8 @@ typedef struct { char *auth_methods[MAX_AUTH_METHODS]; int fingerprint_hash; + + int debian_banner; } ServerOptions; /* Information about the incoming connection as used by Match */ diff --git a/sshd.c b/sshd.c index 96e75c6..7886d0e 100644 --- a/sshd.c +++ b/sshd.c @@ -442,7 +442,8 @@ sshd_exchange_identification(int sock_in, int sock_out) } xasprintf(&server_version_string, "SSH-%d.%d-%.100s%s%s%s", - major, minor, SSH_RELEASE, + major, minor, + options.debian_banner ? SSH_RELEASE : SSH_RELEASE_MINIMUM, *options.version_addendum == '\0' ? "" : " ", options.version_addendum, newline); diff --git a/sshd_config.5 b/sshd_config.5 index 1269bbd..a5afbc3 100644 --- a/sshd_config.5 +++ b/sshd_config.5 @@ -528,6 +528,11 @@ or .Dq no . The default is .Dq delayed . +.It Cm DebianBanner +Specifies whether the distribution-specified extra version suffix is +included during initial protocol handshake. +The default is +.Dq yes . .It Cm DenyGroups This keyword can be followed by a list of group name patterns, separated by spaces.